Tetrazolium and germination procedures for six native range species
by Lory Lee Walter-Dye
A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in
Agronomy
Montana State University
© Copyright by Lory Lee Walter-Dye (1986)
Abstract:
The growing attention in land reclamation has resulted in an increase in native seed sales. As of yet,
germination and viability testing methods have not been established for many native species. For
efficient marketing and subsequent studies on growth and development of native species, the
establishment of optimum testing methods is a prerequisite.
The objective of this paper was to research various treatments and determine which treatment, if any,
were optimum for six native species.
Six species indigenous to the Rocky Mountains and Great Plains regions were evaluated for seed
viability with 2,3,5-triphenyl-2H-tetrazolium chloride (TZ). Specific staining techniques were
developed for each species. Treatments include presoaks, seed coat puncture, seed coat removal,
scarification, and seed bisection. Species tested and their viability values are: 1) Achillea millefolium
L. (Yarrow) 1977 seedlot 94%, 1981 seedlot 65%; 2) Agropyron spicatum (Bluebunch wheatgrass)
1980 seedlot 61%, 1981 seedlot 88%, 1982 seedlot 91%; 3) Calamovilfa longifolia (Prairie sandreed)
1978 seedlot 64%, 1980 seedlot 88%, 1982 seedlot 85%; 4) Elymus cinereus (Basin wildrye) 1980
seedlot 90%, 1981 seedlot 94%, 1982 seedlot 72%; 5) Ratibida columnifera (Prairie cone flower) 1981
seedlot 89%, 1983 seedlot 85% and 6) Sporobolus airoides (Alkali sacaton) 1981JK seedlot 78%,
1981NK seedlot 70%.
Temperature, light environment, prechill, and days of germination were evaluated to determine the
optimum germination method for six species. Results indicate that seven days of germination provided
the best estimation of viability for alkali sacaton, prairie coneflower and prairie sandreed; whereas,
bluebunch wheatgrass, basin wildrye and yarrow required 14 days of germination. The 20C,8L
treatment provided optimum germination for all seedlots of yarrow, prairie coneflower and bluebunch
wheatgrass. All seedlots of prairie sandreed germinated optimally at 25C with either 8 hrs. light or
continuous dark treatment. Basin wildrye seedlots had optimum germination with the 25C,8L and
15-25C,8L treatments; whereas, the 15-25C temperature with either 8 hrs. light or continuous dark
treatment gave optimum germination for alkali sacaton seedlots. Prechilling for 5 or 10 days did not
promote germination with any of the seedlots. TET R A Z O LIU M AND GERM IN A TIO N P R O C E D U R E S
F O R SIX NATIVE R A N G E SPECIES
by
L o ry L e e W a ite r-D y e
A th e s is s u b m itte d in p a r t i a l fu lfillm e n t .
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b e e n found to b e s a tis f a c to r y re g a rd in g c o n te n t, E n g lish u s a g e , f o rm a t,
c ita tio n , b ib lio g ra p h ic s ty le , and c o n s is te n c y , and is re a d y fo r su b m issio n to th e
C o lle g e o f G ra d u a te S tu d ie s.
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A p p ro v ed fo r th e M ajor D e p a r tm e n t
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H e a d , M ajor D e p a r tm e n t
A p p ro v ed fo r th e C o lle g e o f G ra d u a te S tu d ie s
D a te
G ra d u a te D e a n
iii
STA TEM EN T O F PER M ISSIO N TO USE
In p r e s e n tin g th is th e s is in p a r t i a l fu lfillm e n t o f th e r e q u ir e m e n ts fo r a
m a s te r 's d e g re e a t M o n ta n a S ta te U n iv e rs ity , I a g re e t h a t th e L ib ra ry sh a ll
m ak e it a v a ila b le to b o rro w e rs u n d e r ru le s o f th e L ib ra ry .
fro m
th is
th e s is
a re
a llo w a b le
w ith o u t
B rie f q u o ta tio n s
s p e c ia l p e rm iss io n , p ro v id e d
th a t
a c c u r a te a c k n o w le d g m e n t o f s o u rc e is m ad e .
P e rm is sio n fo r e x te n s iv e q u o ta tio n fro m or re p ro d u c tio n o f th is th e s is
m ay b e g r a n te d by m y m a jo r p r o fe s s o r, or in h is a b s e n c e , by th e D ean o f
L ib ra r ie s w hen, in th e o p inion o f e ith e r , th e p ro p o se d use o f th e m a te r ia l is fo r
s c h o la rly p u rp o se s .
A ny co p y in g o r u se o f th e m a te r ia l in th is th e s is fo r
fin a n c ia l g a in sh a ll n o t b e a llo w e d w ith o u t m y p e rm issio n .
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T he a u th o r a c k n o w le d g e s th e
fin a n c ia l su p p o rt o f D e c k e r
C o a l C o .,
M o n ta n a D e p c irtm e n t o f S ta te L an d s, P e a b o d y C o a l C o ., W e ste rn E n e rg y C o a l
C o ., an d W e stm o re la n d R e s o u rc e s , In c. T h a n k s g oes to M r. T om A d sit who w as
in s tr u m e n ta l in o rg a n iz in g th e su p p o rt fo r th e r e s e a r c h p ro g ra m .
S p e c ia l th a n k s go to P ro fe s s o r's L e e H a r t, L o re n W ie s n e r, and J a c k
M a rtin , fo r t h e ir in v a lu a b le in p u t th ro u g h o u t th e p ro g ra m a n d th e ir c r itic a l
re v ie w o f th is th e s is .
T he a u th o r is g r a te f u l fo r th e su p p o rt o f th e M o n ta n a S ta te S eed L ab in
p ro v id in g m a te r ia ls and e q u ip m e n t n e c e s s a ry fo r c o n d u c tin g th e r e s e a rc h ; and,
e s p e c ia lly to th e e m p lo y e e s who h e lp e d o u t d u rin g c r i t ic a l m o m e n ts .
T he a u th o r is a lso in d e b te d to h e r h u sb a n d , G reg , fo r h is u n tir in g su p p o rt,
d e d ic a tio n , and e n e rg y w ith o u t w h ich th e w ritin g o f th is th e s is w ould n o t h a v e
b e e n p o ssib le .
vi
TA BLE O F C O N TEN TS
Page
LIST O F TA B LES.........................................
A B ST R A C T ........................
v iii
xi
C H A P T E R I. L IT E R A T U R E REVIEW .................................................................. ............
I
T e tr a z o liu m ............................................
H is to r y ...........................................
D o rm a n c y ..................................................................................................
G e rm in a tio n .........................................................................................................
T e m p e r a tu r e ..............................................
P r e c h ill................................................................
L ig h t........................
T e m p e r a tu r e In flu e n c e s on P h o to p e rio d .................
I
I
3
4
7
10
11
13
C H A P T E R n . T E T R AZOLIUM VIABILITY P R O C E D U R E S F O R SIX NATIVE
R A N G E SPE C IE S..................
16
I n tr o d u c tio n ..................
M a te r ia ls and M e th o d s.................................. ................ ........ ................... ................
R e s u lts an d D isc u ssio n ............ .
................... ................ ................................ .
T e tra z o liu m T e s tin g P r o c e d u r e s ......................................
Y a r r o w .......................
B lu eb u n ch W h e a tg ra s s ............................................
P r a ir ie S a n d re e d ...... .......................
B asin W ild ry e...... *................................................................
P r a ir ie C o n e flp w e r.........................................................................
A lk a li S a c a to n .............................................................
16
17
18
18
18
18
18
19
19
20
C H A P T E R m . G ERM IN A TIO N P R O C E D U R E S F O R SIX NATIVE
R A N G E SPE C IE S....................
I n tr o d u c tio n .....................................................
M a te r ia ls and M e th o d s....................
R e s u lts and D isc u ssio n ...............
Y a rro w (A c h ille a m ille fo liu m )...............................................................
B lu eb u n ch W h e a tg ra s s (A gropyron s p ic a tu m ). . . . ...................................
P r a ir ie S a n d re e d (C a la m o v ilfa lo n g ifo lia )................................................
B asin W ildrye (E lym us c ln e re u s )...........................
P r a ir ie C o n e flo w e r (R a tih id a c o lu m n ife ra ). ..........................................
A lk a li S a c a to n (S porobolus a iro id e s )..........................................................
24
24
25
'Ll
27
31
37
41
45
48
vii
T A B L E ’O F C O N TE N TS - C o n tin u e d
Page
S u m m a ry .................
Y a rro w ..................
B lu eb im ch W h e a tg ra s s ................... ............................................ .
P r a ir ie S a n d re e d ............. .................................................. .....................
B asin W ild ry e ...... .................................................................. ..................
P r a ir ie C o n e flo w e r..................
A lk a li S a c a to n .....................
R E F E R E N C E S C IT E D ................................... *....................................... .................. .............
52
53
53
53
53
54
54
55
viii
LIST O F TABLES
T a b le
Page
1.
T e tra z o liu m v ia b ility p ro c e d u re s fo r six n a tiv e ra n g e s p e c ie s .
21
2.
P e r c e n ta g e v ia b ility , e f f e c t o f la c to p h e n o l, e f f e c t o f se e d c o a t
p r e p a r a tio n on s ta in in g , an d te tr a z o liu m s ta in in g tim e e v a lu a tio n
fo r six n a tiv e ra n g e sp e c ie s .
22
P e r c e n ta g e v ia b ility , a s d e te rm in e d by TZ s ta in in g , fo r fo u r
s c a r if ic a tio n t r e a tm e n ts w hen a v e ra g e d o v e r tw o a lk a li s a c a to n
s e e d lo ts . S e e d s w e re TZ s ta in e d fo r 24 h o u rs.
23
P e r c e n ta g e v ia b ility o f 0 and 2 s e c o n d s o f s c a r if ic a tio n w ith
TZ s ta in in g tim e . P e r c e n ta g e s a re th e a v e ra g e o f tw o a lk a li
s a c a to n s e e d lo ts .
23
P e r c e n ta g e g e rm in a tio n o f tw o y a rro w s e e d lo ts w ith tim e w hen
a v e ra g e d o v e r fiv e te m p e r a tu r e and lig h t c o m b in a tio n s .
28
P e r c e n ta g e g e rm in a tio n o f tw o y a rro w s e e d lo ts w ith tim e w hen
g e rm in a te d a t v a rio u s te m p e r a tu r e and lig h t c o m b in a tio n s .
29
C o m p a riso n o f p e r c e n t v ia b ility w ith fiv e te m p e r a tu r e and
lig h t c o m b in a tio n 's p e r c e n ta g e g e rm in a tio n fo r tw o y a rro w
s e e d lo ts .
29
P e r c e n ta g e g e rm in a tio n o f th r e e p r e c h ill t r e a tm e n ts w ith tim e .
P e r c e n ta g e s a re a v e ra g e d o v e r tw o y a rro w s e e d lo ts and fiv e
te m p e r a tu r e and lig h t c o m b in a tio n s .
30
P r e c h ill e f f e c t on tw o y a rro w s e e d lo t's p e r c e n ta g e g e rm in a tio n .
S e e d lo ts w e re g e rm in a te d a t fiv e te m p e r a tu r e and lig h t
c o m b in a tio n s fo r 14 d ay s.
31
P e r c e n ta g e g e rm in a tio n o f th r e e b lu e b u n c h w h e a tg ra s s s e e d lo ts
w ith tim e w hen a v e ra g e d o v er fiv e te m p e r a tu r e and lig h t
c o m b in a tio n s .
32
P e r c e n ta g e g e rm in a tio n o f th r e e b lu e b u n c h w h e a tg ra s s s e e d lo ts
w ith tim e w hen g e rm in a te d a t v a rio u s te m p e r a tu r e an d lig h t
c o m b in a tio n s .
33
3.
4.
5.
6.
7.
8.
9.
10 .
11 .
ix
L ist of T ables - (Continued)
T a b le
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
Page
C o m p a riso n o f p e r c e n t v ia b ility w ith fiv e te m p e r a tu r e and
lig h t c o m b in a tio n 's p e r c e n ta g e g e rm in a tio n fo r th r e e b lu eb u n c h
w h e a tg ra s s s e e d lo ts .
34
P r e c h ill e f f e c t on p e r c e n ta g e g e rm in a tio n fo r fiv e te m p e r a tu r e
an d lig h t c o m b in a tio n s . P e r c e n ta g e g e rm in a tio n w as a v e ra g e d
o v e r th r e e b lu e b u n c h w h e a tg ra s s s e e d lo ts .
36
P r e c h ill e f f e c t on th r e e b lu eb u n c h w h e a tg ra s s s e e d lo t's
p e r c e n ta g e g e rm in a tio n . S e e d lo ts w e re g e rm in a te d a t fiv e
t e m p e r a tu r e and lig h t c o m b in a tio n s .
37
P e r c e n ta g e g e rm in a tio n o f fiv e t e m p e r a tu r e and lig h t
c o m b in a tio n s w ith tim e . P e r c e n ta g e s w e re a v e ra g e d o v e r
th r e e p r a ir ie s a n d re e d s e e d lo ts .
38
C o m p a riso n o f p e r c e n t v ia b ility w ith fiv e te m p e r a tu r e and lig h t
c o m b in a tio n 's p e r c e n ta g e g e rm in a tio n fo r th r e e p r a ir ie s a n d re e d
s e e d lo ts .
39
C o m p a riso n o f p e r c e n ta g e g e rm in a tio n am o n g c o n tin u o u s d a rk
a n d 8 h rs. lig h t t r e a tm e n ts w hen a v e ra g e d o v e r th r e e p r a ir ie
s a n d re e d s e e d lo ts . S e e d s w e re g e rm in a te d a t 25C a n d 2 0C .
40
P r e c h ill e f f e c t on th r e e p r a ir ie s a n d re e d s e e d lo t's p e r c e n ta g e
g e rm in a tio n . S e e d lo ts w e re g e rm in a te d a t fiv e t e m p e r a tu r e
a n d lig h t c o m b in a tio n s fo r 7 d a y s.
41
P e r c e n ta g e g e rm in a tio n o f fiv e te m p e r a tu r e and lig h t
c o m b in a tio n s w ith tim e . P e r c e n ta g e s a re a v e ra g e d o v e r th r e e
b a s in w ild ry e s e e d lo ts .
.
42
C o m p a riso n o f p e r c e n t v ia b ility w ith fiv e te m p e r a tu r e a n d lig h t
c o m b in a tio n 's p e r c e n ta g e g e rm in a tio n fo r th r e e b a s in w ild ry e
s e e d lo ts .
43
P r e c h ill e f f e c t on p e r c e n ta g e g e rm in a tio n fo r fiv e t e m p e r a tu r e
a n d lig h t c o m b in a tio n s . P e r c e n ta g e s w e re a v e ra g e d o v e r th r e e
b a s in w ild ry e s e e d lo ts .
43
P r e c h ill e f f e c t on th r e e b a s in w ild ry e s e e d lo t's p e r c e n ta g e
g e rm in a tio n . S e e d lo ts w e re g e rm in a te d a t fiv e t e m p e r a tu r e
a n d lig h t c o m b in a tio n s fo r 14 d a y s.
44
X
L ist of T ables - (Continued)
T a b le
23.
24.
25.
26 .
27.
28.
29.
Page
P e r c e n ta g e g e rm in a tio n o f tw o p r a ir ie c o n e flo w e r s e e d lo ts w ith
tim e w hen g e rm in a te d a t v a rio u s te m p e r a tu r e and lig h t
c o m b in a tio n s .
45
C o m p a riso n o f p e r c e n t v ia b ility w ith fiv e te m p e r a tu r e and lig h t
c o m b in a tio n 's p e r c e n ta g e g e rm in a tio n fo r tw o p r a ir ie c o n e flo w e r
s e e d lo ts .
.46
P re c h ill e f f e c t on tw o p r a ir ie c o n e flo w e r se e d lo t's p e r c e n ta g e
g e rm in a tio n . S e e d lo ts w e re g e rm in a te d a t fiv e te m p e r a tu r e
an d lig h t c o m b in a tio n s fo r 7 d ay s.
48
P e r c e n ta g e g e rm in a tio n o f fiv e t e m p e r a tu r e and lig h t
c o m b in a tio n s w ith tim e . P e r c e n ta g e s a re a v e ra g e d o v e r tw o
a lk a li s a c a to n s e e d lo ts .
49
C o m p a riso n o f p e r c e n t v ia b ility w ith fiv e te m p e r a tu r e an d lig h t
c o m b in a tio n 's p e r c e n ta g e g e rm in a tio n fo r tw o a lk a li s a c a to n
s e e d lo ts .
50
C o m p a riso n o f p e r c e n ta g e g e rm in a tio n am o n g c o n tin u o u s d a rk
an d 8 h rs. lig h t t r e a tm e n ts fo r tw o a lk a li s a c a to n s e e d lo ts .
S e e d s w e re g e rm in a te d a t 15 -2 5 C a n d 20C fo r 7 d ay s.
51
P r e c h ill e f f e c t on tw o a lk a li s a c a to n s e e d lo t's p e r c e n ta g e
g e rm in a tio n . S e e d lo ts w e re g e rm in a te d a t fiv e t e m p e r a tu r e
a n d lig h t c o m b in a tio n s fo r 7 d ay s.
52
xi
A B STR A C T
T h e g ro w in g a tt e n ti o n in land r e c la m a tio n h a s r e s u lte d in an in c re a s e in
n a tiv e s e e d s a le s . A s o f y e t, g e rm in a tio n a n d v ia b ility te s tin g m e th o d s h a v e n o t
b e e n e s ta b lis h e d fo r m an y n a tiv e s p e c ie s .
F o r e f f ic ie n t m a rk e tin g
an d
s u b s e q u e n t s tu d ie s on g ro w th and d e v e lo p m e n t o f n a tiv e s p e c ie s , th e
e s ta b lis h m e n t o f o p tim u m te s tin g m e th o d s is a p r e r e q u is ite .
T he o b je c tiv e o f th is p a p e r w as to r e s e a r c h v a rio u s t r e a tm e n ts and
d e te r m in e w h ich t r e a t m e n t , if any, w e re o p tim u m fo r six n a tiv e s p e c ie s .
Six s p e c ie s in d ig e n o u s to th e R o c k y M o u n ta in s and G r e a t P la in s re g io n s
w e re e v a lu a te d fo r s e e d v ia b ility w ith 2 ,3 ,5 - tr ip h e n y l-2 H -te tr a z o liu m c h lo rid e
(TZ).
S p e c ific s ta in in g te c h n iq u e s w e re d e v e lo p e d fo r e a c h sp e c ie s .
T r e a tm e n ts in c lu d e p re s o a k s , s e e d c o a t p u n c tu r e , s e e d c o a t re m o v a l,
s c a r if ic a tio n , and se e d b is e c tio n . S p e c ie s t e s t e d and th e ir v ia b ility v a lu e s a re :
I) A c h ille a m ille fo liu m L . (Y arrow ) 1977 s e e d lo t 94% , 1981 s e e d lo t 65% ; 2)
A g ro p y ro n s p ic a tu m (B luebunch w h e a tg ra s s ) 1980 s e e d lo t 61% , 1981 s e e d lo t
88% , 1982 s e e d lo t 91% ; 3) C a Ia m o v ilfa lo n g ifo lia ( P ra irie sa n d re e d ) 1978
s e e d lo t 64% , 1980 s e e d lo t 88% , 1982 s e e d lo t 85% ; 4) E ly m u s c in e re u s (Basin
w ildrye) 1980 s e e d lo t 90% , 1981 s e e d lo t 94% , 1982 s e e d lo t 72% ; 5) R a tib id a
c o lu m n if e ra (P ra irie co n e flo w er) 1981 s e e d lo t 89% , 1983 s e e d lo t 85% and 6)
SporoboIus a iro id e s (A lkali s a c a to n ) 1981JK s e e d lo t 78% , 1981NK s e e d lo t 70% .
T e m p e r a tu r e , lig h t e n v iro n m e n t, p r e c h ill, and d ays o f g e rm in a tio n w e re
e v a lu a te d to d e te r m in e th e o p tim u m g e rm in a tio n m e th o d fo r six s p e c ie s .
R e s u lts in d ic a te t h a t se v e n d ay s of g e rm in a tio n p ro v id e d th e b e s t e s tim a tio n o f
v ia b ility fo r a lk a li s a c a to n , p r a ir ie coneflow .er and p r a ir ie s a n d re e d ; w h e re a s ,
b lu e b u n c h w h e a tg ra s s , b a sin w ild ry e an d y a rro w re q u ir e d 14 d ay s o f
g e rm in a tio n . T h e 2 0 C ,8 L t r e a tm e n t p ro v id e d o p tim u m g e rm in a tio n fo r a ll
s e e d lo ts o f y a rro w , p r a ir ie c o n e flo w e r and b lu eb u n c h w h e a tg ra s s . A ll s e e d lo ts
o f p r a ir ie s a n d re e d g e rm in a te d o p tim a lly a t 25C w ith e ith e r 8 h rs. lig h t or
c o n tin u o u s d a rk t r e a t m e n t . B asin w ild ry e s e e d lo ts h a d o p tim u m g e rm in a tio n
w ith th e 2 5 C ,8 L an d 1 5 -2 5 C ,8 L tr e a tm e n ts ; w h e re a s , th e 15 -2 5 C te m p e r a tu r e
w ith e ith e r 8 h rs. lig h t or c o n tin u o u s d a rk t r e a t m e n t g a v e o p tim u m g e rm in a tio n
fo r a lk a li s a c a to n s e e d lo ts .
P re c h illin g fo r 5 o r 10 d ay s did n o t p ro m o te
g e rm in a tio n w ith an y o f th e s e e d lo ts .
I
CH APTER I
L IT E R A T U R E REVIEW
T e tra z o liu rn
E f f ic ie n t
seed
p ro d u c tio n
and
m a r k e tin g
depends
upon
th e
p ro p e r
e v a lu a tio n o f s e e d q u a lity .
Tw o m e th o d s e m p lo y e d to e v a lu a te q u a lity a re
p u r ity and g e rm in a tio n t e s t s .
R e s u lts fo r th e fo rm e r c a n b e o b ta in e d in a few
h o u rs, w h e re a s th e l a t t e r m ay ta k e w e e k s.
T he tim e re q u ire d fo r g e rm in a tio n
t e s t s c a n h in d e r se e d p ro c e s s in g and m a rk e tin g . T his s itu a tio n n e c e s s ita te d th e
n e e d to d e v e lo p a m o re ra p id m e th o d fo r e v a lu a tin g th e g e rm in a tiv e p o te n tia l
o f se e d s.
H is to ry
F ir s t e x p e rim e n ts c o n d u c te d in th e s e a r c h fo r a ra p id v ia b ility t e s t b e g a n
in th e e a rly 1900's. S e v e ra l s c ie n tis ts
e x p lo re d th e p o s s ib ilitie s o f e le c tr o ly te
le a c h in g (D a rsie e t a l., 1914), h e a t lib e r a tio n (C hing, I9 6 0 ), a n d f r e e f a t t y a c id
c o n te n t (H ibbard an d M ille r, 1928) as a m e a n s fo r in d ic a tin g ra p id v ia b ility .
T h e se m e th o d s w e re c ite d a s b e in g r e lia b le in d ic a to rs , b u t w e re d iff ic u lt to
e v a lu a te .
T h e se t e s t s , a t th e ir b e s t, w e re c a p a b le o f e v a lu a tin g v ia b ility o f a
la r g e q u a n tity o f s e e d s a s low , m ed iu m , o r h ig h r a t h e r th a n in p e r c e n ta g e s .
R e s e a rc h e rs re c o g n iz e d t h a t te c h n iq u e s to a sse ss se e d q u a lity n e e d e d to
b e b a s e d on in d iv id u a l s e e d s r a t h e r th a n on a. q u a n tity o f s e e d s .
T he v ita l
s ta in in g te c h n iq u e s d if f e r e n tia lly s ta in liv e and d e a d tis s u e , an d w e re th e f ir s t
to m e e t th is r e q u ir e m e n t.
D r. N elju b o w , in 1925,
d e v e lo p e d th e f ir s t r e lia b le
2
v i ta l s ta in in g m e th o d (D elouche e t a l, 1962).
T he te c h n iq u e w as b a s e d on th e
s ta in in g o f d e a d tis s u e w ith indigo c a rm in e , an a n ilin e d y e .
E v a lu a tio n w as
b a s e d on th e r e la tiv e p ro p o rtio n o f c o lo re d and u n c o lo re d tis s u e .
L a t e r , v ita l s ta in in g te c h n iq u e s w e re d e v e lo p e d .
b a s e d on th e m e ta b o lic p ro c e s s e s o f s e e d s .
in v e s tig a te d .
S ince
th e
a c tiv ity
of
T h e se te c h n iq u e s w e re
M ore s p e c ific a lly , e n z y m e s w e re
enzym es
can
be
e a s ily
m e a s u re d ,
in v e s tig a to rs a tt e m p t e d to c o r r e la te th e ir a c tiv ity w ith se e d v ia b ility .
P e ro x id a s e (M cH arg u e, 1920) and c a ta la s e
a c ti v it y w as c o n s id e re d .
(D avis, 1926; L e g a tt, 1938)
M e th o d s b a s e d upon p e ro x id a s e a n d c a ta la s e w e re
l a t e r d e v e lo p e d to b e c o m e re lia b le in d ic a to r s , b u t th e y w e re lim ite d by th e ir
in a b ility to b e b a s e d on in d iv id u a l s e e d s . D r. T u re sso n , in 1922, w as th e f ir s t to
w ork w ith th e d e h y d ro g e n a se e n z y m e s (D elouche e t a l, 1962).
T h e se e n z y m e s
a re in v o lv e d in th e o x id a tio n -re d u c tio n r e a c tio n s o f o rg a n ic co m p o u n d s.
B o th
th e o x id iz e d and re d u c e d fo rm s a re d istin g u is h a b le by th e ir c h a n g e in c o lo r.
H a s e g a w a, in 1935, r e p o r te d on a se le n iu m m e th o d fo r d e te rm in in g se e d
v ia b ility
(D elouche
et
a l,
1962).
T he
p a r t i c i p a te s on liv in g tis s u e w hen re d u c e d .
se le n iu m
s a lts
p ro d u c e d
c o lo re d
R e d u c tio n w as b e lie v e d to r e s u lt
fro m th e p r e s e n c e o f a c tiv e d e h y d ro g e n a se e n z y m e s . T he s e le n ite m e th o d w as
f u r th e r d e v e lo p e d by E id m a n n in 1938 (D elo u ch e e t a l, 1962). L a k o n d e v e lo p e d
th e s e le n ite to p o g ra p h ic a l m e th o d t h a t s tr e s s e d th e an a ly sis o f in d iv id u al se e d s
a n d r e s u lte d in im p ro v e d a c c u r a c y o f th e r a p id s e le n ite v ia b ility t e s t (D elouche
e t a l, 1962).
T his m e th o d w as c o n s id e re d v e ry r e lia b le , b u t h a d one se rio u s
d ra w b a c k ; s e le n iu m 's to x ic ity
and i ts p o t e n t ia l d a n g e r to th e u s e r.
U pon
h e a rin g o f th e d isc o v e ry o f te tr a z o liu m s a lt by tw o G e rm a n s c ie n tis ts , L akon
s u b s titu te d th e se le n iu m
fo r th e te tr a z o liu m
s a lt.
T he te tr a z o liu m s a lt is
re d u c e d fro m a c o lo rle s s , so lu b le fo rm , to in so lu b le , c o lo re d fo rm a z a n s in th e
3
p rese n c e
o f liv in g tis s u e .
L ak o n c o n c lu d e d t h a t th is m e th o d a llo w e d th e
p r e d ic tio n o f th e g e rm in a b ility o f s e e d s by o b s e rv a tio n o f th e s ta in e d em b ry o
p a rts .
S e v e ra l s c ie n tis ts
( C o ttr e ll, 1947; P o r te r e t a l, 1947; Shuel, 1948)
e m p lo y e d th is te c h n iq u e and a g re e d t h a t r e s u lts from th e te tr a z o liu m t e s t did
in d e e d show c lo se a g re e m e n t w ith g e rm in a tio n t e s t s .
T o d ay th e te tr a z o liu m t e s t is a u n iv e rs a lly a c c e p te d m e th o d fo r ra p id ly
e v a lu a tin g se e d v ia b ility . I t h a s b e e n a d a p te d to a c c o m m o d a te a w ide ra n g e o f
s p e c ie s in e v a lu a tin g se e d q u a lity .
S eed in d u s trie s re ly on th e te tr a z o liu m t e s t
in c o n ju n c tio n w ith o r in p la c e o f th e s ta n d a rd g e rm in a tio n t e s t s .
D o rm a n c y
T he in a b ility o f v ia b le se e d s to g e rm in a te u n d e r fa v o ra b le c o n d itio n s is
r e f e r r e d to as d o rm a n c y (V illiers, 1972; C o p e la n d , 1976).
T his is a w id e sp re a d
p h e n o m e n o n found p r im a rily in th e t e m p e r a t e re g io n s and to so m e e x te n t in
tr o p ic a l a n d s u b tro p ic a l re g io n s . D o m e s tic a te d p la n ts show le s s d o rm a n c y th a n
w ild p la n ts (C o p elan d , 1976).
D o rm a n c y is b io lo g ic a lly a d v a n ta g e o u s fo r so m e
s p e c ie s , a s i t a llo w s th e p la n ts g ro w th c y c le to a d a p t to th e e n v iro n m e n ta l
v a ria tio n s
(V illiers,
u n fa v o ra b le .
1972).
A g ro n o m ic a lly
sp e ak in g ,
d o rm an t
se e d s
a re
A h ig h p e r c e n ta g e o f d o rm a n t se e d s w ould r e s u lt in n o n u n ifo rm
s ta n d and m a tu r a tio n o f p la n ts .
V egis (1964) d e fin e d d o rm a n c y
eis
a c o n d itio n in w hich n o r m a l g e rm in a tio n
fa ils to o c c u r re g a rd le s s o f e x te r n a l c o n d itio n s .
T his d e fin itio n se e m s to o
r e s t r i c t i v e sin c e it d o es n o t in clu d e a r t i f i c i a l m a n ip u la tio n o f th e se e d , such
re m o v a l o f th e se e d c o a t.
e n v iro n m e n ta l
an d
els
O th e rs e m p lo y e d th e te r m d o rm a n c y to in clu d e b o th
in te r n a l
c o n d itio n s
th a t
p re v e n t
p r o c e s s e s (P o llo ck and T o o le , 1961; A m en , 1968).
n o rm al
g e rm in a tio n
B e c a u se d o rm a n c y is an
4
e lu s iv e p h e n o m e n o n , a p r e c is e d e fin itio n h a s y e t to b e d e v e lo p e d a n d u n iv e rs a lly
a c c e p te d .
A R u ssian s c ie n tis t, N ik lo a e v a , (V illiers, 1972) d e v is e d a d e ta ile d
d o rm a n c y c la s s if ic a tio n s c h e m e .
H e d e fin e d fo u r ty p e s o f d o rm a n c y re s u ltin g
fro m ; a) p r o p e r tie s o f th e o u te r c o v e rs o f th e e m b ry o , b) im m a tu r ity o f th e
e m b ry o , c) p h y s io lo g ic a l c o n d itio n o f th e e m b ry o , and d) ty p e s o f co m b in ed
d o rm a n c y .
A m o re
s im p lifie d
c la s s if ic a tio n
o f d o rm a n c y
ty p e s
w as d e v ise d by
C ro c k e r (1916) who d e s c rib e d d o rm a n c y r e s u ltin g fro m ; a) im m a tu r e e m b ry o , b)
im p e rm e a b le s e e d c o a ts to w a te r , c) m e c h a n ic a l r e s is ta n c e o f t h e se e d c o a ts to
e m b ry o g ro w th , d) low p e rm e a b ility o f s e e d c o a ts to g a s e s , e) d o rm a n c y
r e s u ltin g fro m a m e ta b o lic b lo c k w ith in th e e m b ry o its e lf , f) a n y c o m b in a tio n o f
th e a b o v e , g) s e c o n d a ry d o rm a n c y .
fo r
c o m p a riso n s
T his c la s s if ic a tio n h a s p ro v id e d th e b a s is
o f e x p e rim e n ta l in v e s tig a tio n s b e tw e e n d o rm a n c y -in d u c in g
m e c h a n is m s and d o rm a n c y -b r e a k in g m e c h a n ism s.
G e rm in a tio n
A
seed
c o n ta in s
an
e m b ry o n ic
g e rm in a tio n is its re s u m p tio n o f g ro w th .
p la n t
in
an
in a c tiv e
c o n d itio n ,
and
G e rm in a tio n is s a id to h a v e o c c u rre d
w hen th e r a d ic le h a s b u rs t th ro u g h its o u te r s tr u c tu r e s (Toole e t a l, 1956). C e ll
d iv isio n and e lo n g a tio n s t a r t s a t th is tim e ; a n d m any se e d p h y sio lo g ists ta k e
th e s e e v e n ts as th e te r m in a tio n o f g e rm in a tio n and th e b e g in n in g o f se ed lin g
d e v e lo p m e n t
(B ew ley
and
B la c k ,
1985;
B e r r ie ,
1984).
In
so m e
seeds
d e v e lo p m e n t s t a r t s as soon as w a te r is a b so rb e d ; h o w e v e r, in o th e r s p e c ie s
g e rm in a tio n d o e s n o t ta k e p la c e u n til o th e r re q u ir e m e n ts a re fu lfille d .
T h re e
d is tin c t p h a s e s o f g e rm in a tio n a re e a sily m e a s u ra b le w ith in th e s e e d . T hey a re
im b ib itio n , c e ll e lo n g a tio n , a n d an in c re a s e in c e ll n u m b e r (T oole e t a l, 1956).
5
W hen d ry s e e d s a r e e x p o sed to w a te r th e in itia l u p ta k e is ra p id , fo llo w ed
by a slo w e r u p ta k e r e f e r r e d to as th e la g p e rio d .
S u c c e e d in g th e la g p e rio d is
a n o th e r b u r s t o f ra p id w a te r u p ta k e , a n d th e n g e rm in a tio n p ro c e e d s (B errie,
1984).
M e a su ra b le in c r e a s e s in r e s p ir a tio n ,
enzym e
a c tiv ity ,
and p r o te in
s y n th e s is b e g in s s h o rtly a f t e r th e s t a r t o f im b ib itio n . It is a t th is tim e th e se ed
c h a n g e s fro m
b e in g b io lo g ic a lly in e r t to b e c o m in g a fu lly
a c tiv e ly m e ta b o liz in g o rg a n ism .
i n te g r a te d
and
D u rin g th e la g p h a se it is th o u g h t t h a t th e
m e ta b o lic p a th w a y b e g in s to allow th e in itia tio n o f th e g e rm in a tio n p ro c e s s
(B e rrie , 1984).
S u g g e stio n s h a v e b e e n m ad e p e rta in in g to m e m b ra n e s as b e in g th e lo cu s
fo r th e s tim u lu s o f g e rm in a tio n (H en d rick s a n d T a y lo rso n , 1976). T he n a tu r e o f
th e p h o sp h o lip id b y la y e rs is su ch
t h a t its p h y s ic a l p r o p e r tie s c a n b e ch a n g ed by
m a n ip u la tin g th e g e rm in a tin g t e m p e r a tu r e .
w ith d e g re e o f p e rm e a b ility .
T h e p h a se c h a n g e s a re a s s o c ia te d
A t h ig h te m p e r a tu r e s p e rm e a b ility is in c re a s e d
b e c a u s e th e b y la y e rs a re in a liquid s t a t e .
T his r e s u lts in a g r e a t e r loss o f
am in o a c id s w h ich s u b s e q u e n tly r e d u c e s g e rm in a tio n .
A t low te m p e r a tu r e s
p e r m e a b ility is low b e c a u s e th e b y la y e rs a re in a solid s t a t e .
In th e m iddle
t e m p e r a tu r e ra n g e th e b y la y e rs e x is t in a liq u id -c r y s ta l s t a t e (H en d rick s and
T a y lo r son, 1976; M urphy a n d N o lan d , 1982).
s u g g e s te d
t h a t p h y to c h ro m e
p r o p e r tie s and r e a c tio n s .
m ay also b e
H e n d ric k s and T a y lo rso n (1979)
in v o lv e d in c h a n g in g m e m b ra n e
Som e r e p o r ts c ite t h a t g ib b e re llic a c id (GA) a c ts on
th e m e m b ra n e s o f c e lls and o rg a n e lle s and t h a t i ts e f f e c t on s e e d g e rm in a tio n is
also a t th is le v e l (B e rrie ,
1984).
T he
m e m b ra n e p r o p e r tie s h a v e s tr e n g th e n e d
a s s o c ia tio n
o f th e s e
f a c to r s
w ith
th e view t h a t th e m e m b ra n e m ay
in d e e d b e th e lo cu s fo r th e s tim u lu s o f g e rm in a tio n .
6
U n lik e th e im b ib itio n p h a se w h e re the; only m o rp h o lo g ic a l c h a n g e is an
in c r e a s e in v o lu m e , th e o th e r tw o p h a s e s in v o lv e a m a rk e d c h a n g e in th e s iz e o f
th e e m b ry o n ic a x is, an d th e b e g in n in g s o f d e v e lo p m e n t.
m o rp h o lo g ic a l
changes
th e r e
a re
also
c e llu la r
e s p e c ia lly in s to r a g e a n d r e g u la to r y tis s u e s .
and
In p a r a lle l w ith th e
su b c e llu la r
c h a n g e s,
A ll th e c h a n g e s a re a s s o c ia te d
w ith c o n v e rsio n , m o b iliz a tio n , tra n s lo c a tio n and r e d is tr ib u tio n o f th e s e e d s
s to r a g e
m a te r ia l (B e rrie, 1984).
M o b iliz a tio n o f th e e n d p s p e rm ic r e s e r v e s
c a n n o t ta k e p la c e w ith o u t th e em b ry o and s c u te llu m . T he e m b ry o w as found to
c o n tr o l
th e
h y d ro ly tic
c a p a c ity
o f th e
a le u ro n e
and
c o u ld
in flu e n c e
th e
fu n c tio n in g o f t h a t tis s u e (B e rrie , 1984).
E m b ry o -le ss s e e d s c a n n o t a c c o m p lis h th e d isso lu tio n o f s ta r c h .
Tw o
e n z y m e s , b e ta -a m y la s e , and a lp h a -a m y la s e , a re re sp o n sib le fo r th e d ig e s tio n o f
s ta r c h y m a te r ia l an d m o b iliz a tio n o f th e s e food r e s e r v e s to th e e x te n d in g ax is
(B e rrie , 1984). B e ta -a m y la s e is p r e s e n t w ith in th e se e d and a p p e a rs only a f t e r
th e ra d ic le h a s e m m e rg e d .
E a rly w o rk s in th e n in e te e n th c e n tu r y found th e
e m b ry o and s c u te llu m to b e re sp o n sib le fo r th e r e le a s e o f a lp h a -a m y la s e an d
lip a s e d u rin g e a rly s ta g e s o f g e rm in a tio n (B row n and M o rris,! 89.0). T he a m o u n t
o f a lp h a -a m y la s e s e c r e te d h o w e v e r, w as n o t s u f f ic ie n t to b r e a k dow n th e e n tir e
e n d o sp e rm s to r a g e m a te r ia l.
Y om o (I960) an d P a le g (1961) found t h a t th e e m b ry o re g io n o f c e r e a l
g ra in s s e c r e te d GA to th e a le u ro n e and t h a t th is la y e r re sp o n d e d by d e v e lo p in g
in c r e a s e d a m o u n ts o f th e tw o d ig e s tiv e e n z y m e s . G ib b e re llic a c id p ro m o tio n o f
e n z y m e a c tiv ity h a s b e e n found to b e d e p e n d e n t on R N A an d p r o te in sy n th e sis
(C h risp e e ls an d V a rn e r, 1967; D u re , 1979).
In c o n tr a s t to G A , a m o re r e c e n t
s tu d y s u g g e sts t h a t th e s e e d s o s m o tic p o t e n t ia l c o n tro ls th e p ro d u c tio n o f th e
h y d ro ly tic e n z y m e s (T re w av a s, 1982). W here f a t is th e m ain s to r a g e s u b s ta n c e ,
7
lip a s e is th e p re d o m in e n t d ig e s tiv e e n z y m e (B e rrie, 1984). I ts a c ti v it y in c re a s e s
d u rin g th e
c o u rse o f g e rm in a tio n , b u t th e
C ontrol m e c h a n ism
fo r th is
is
unknow n. T h e p re s e n c e o f GA h a s no e f f e c t on in c re a s in g th e a c tiv ity o f lip a se
(B e rrie, 1984).
M any a tt e m p t s h a v e b e e n m ad e to p in p o in t th e trig g e rin g s tim u lu s fo r th e
o n s e t o f g e rm in a tio n .
a lo n e
As o f y e t th e r e is no c o n c r e te p ro o f t h a t one p ro c e s s
is re s p o n s ib le fo r th e in d u c tio n o f g e rm in a tio n .
R a th e r , a co m p le x
in v o lv e m e n t o f s e v e r a l p ro c e s s e s and p a th w a y s , e a c h p ro b a b ly in one w ay o r
a n o th e r d e p e n d e n t upon th e o th e r , s e e m s to b e n e c e s s a ry fo r g e rm in a tio n to
o c c u r.
It
should
be
n o te d
th a t
e x te r n a l
f a c to r s
such
as
m o is tu re
fo r
re h y d r a tio n , lig h t, t e m p e r a tu r e , and o x y g en also p la y a m a jo r ro le in th e
in itia tio n or p r e v e n tio n o f g e rm in a tio n .
T e m p e r a tu r e
T he f ir s t s tu d y on th e in flu e n c e o f te m p e r a tu r e on s e e d g e rm in a tio n w as
th a t
of L efeb u re,
w h ich
w as p u b lish e d
in
1801
(Lang,
1965).
L e fe b u re
i n te r p r e te d h is r e s u lts in p h y s ic a l c o n c e p ts a n d te r m s w h ich h a v e sin ce b e e n
abandoned,
but
h is
e x p e rim e n ta l
su b se q u e n t w ork done in th is a r e a .
d a ta
w as
r e p r e s e n ta tiv e
of
a lm o st
a ll
T h o ro u g h in v e s tig a tio n s on th e e f f e c ts o f
c o n s ta n t te m p e r a tu r e on se e d g e rm in a tio n o f s e v e r a l c u ltiv a te d p la n ts w as
s tu d ie d in I8 6 0 by J . S a c h s (R o lle r, 1972).
H is s tu d ie s sh o w ed t h a t th e s e e d s
g e rm in a tiv e a b ility im p ro v e d as te m p e r a tu r e in c re a s e d fro m its lo w er lim it
u n til a c e r ta in te m p e r a tu r e w as r e a c h e d ab o v e w hich a n y f u r th e r in c re a s e in
te m p e r a tu r e r e s u lte d in re d u c e d p e rf o r m a n c e (R o lle r, 1972; B e w le y and B lack ,
1985). B ased on th e s e r e s u lts , h e f o rm u la te d th e c o n c e p t o f th e th r e e c a rd in a l
te m p e r a tu r e s ; m in im u m , o p tim u m , and m ax im u m (Lang, 1965).
8
M ost se e d s g e rm in a te o v e r a w ide ra n g e o f te m p e r a tu r e s . T h e ir w id th and
o p tim u m is h ig h ly in flu e n c e d b y su ch f a c to r s as se e d a g e , s e e d c o a t, p re c h illin g
a f te r - r ip e n in g , g e n e tic v a ria b ility , v ig o r, d u ra tio n o f in c u b a tio n period^ e tc .
(E vans, 1922; H a rrin g to n , 1923; L an g , 1965; R o lle r, 1972).
Such s h ifts in
t e m p e r a tu r e h a v e b e e n o b s e rv e d in s e e d s o f b a rle y , w h e a t, a s p a ra g u s , c o n ife rs ,
and o th e rs ; a lth o u g h , th e r e a re som e se e d s in w hich th e o p tim u m d o es re m a in
c o n s ta n t (L ang, 1965). S om e se e d s h a v e th e c a p a c ity to g e rm in a te e q u a lly w e ll
w ith
a
w ide
ra n g e
te m p e r a tu r e o p tim u m .
of
te m p e r a tu r e s
w h ile
o th e r s
have
a
v e ry
d e fin ite
F o r in s ta n c e , la rk s p u r s e e d g e rm in a te s m u ch b e t t e r a t
15C , w h ich r e p r e s e n ts its o p tim u m , th a n a t 18C ; w hile m an y c u ltiv a te d p la n ts
g e rm in a te w ith e q u a l c o m p le te n e s s b e tw e e n 15C and 30C (H a rrin g to n , 1923;
L an g , 1965).
T he tim e n e e d e d fo r r e a c h in g m ax im u m g e rm in a tio n v a rie s w ith
te m p e r a tu r e . In c re a s in g th e te m p e r a tu r e m e a n s t h a t g e rm in a tio n s t a r t s e a r lie r
an d is in itia lly m o re ra p id .
In som e s p e c ie s , in c re a s in g t e m p e r a tu r e can also
c a u se a ris e in p e r c e n ta g e g e rm in a tio n .
H o w e v e r, in c re a s in g th e te m p e r a tu r e
ab o v e th e s p e c ie s m ax im u m w ill r e s u lt in re d u c e d p e r f o r m a n c e . T his d e c lin e in
s e e d g e rm in a tio n is th e r e s u lt o f th e rm o d o rm a n c y and is e s p e c ia lly p ro m in e n t in
se e d s t h a t
a re
e x p o sed
fo r a p ro lo n g e d p e rio d o f tim e
to
ab o v e o p tim a l
te m p e r a tu r e s (H a rrin g to n , 1923; R o lle r, 1972; B ew ley and B la c k , 1985).
F r e q u e n tly , f a s t e r g e rm in a tio n r a t e s and h ig h e r p e r c e n ta g e s a re o b ta in e d
w ith
f lu c tu a tin g
t e m p e r a tu r e s .
T he m o st s trik in g e f f e c t , h o w e v e r, is an
in c r e a s e in g e rm in a tio n c a p a c ity (Lang, 1965; R o lle r, 1972).
L ie b e n b e rg w as
th e f ir s t to r e p o r t th e fa v o ra b le e f f e c ts o f d iu rn a l te m p e r a t u r e flu c tu a tio n s
u sin g a n n u a l b lu e g ra s s . S in ce th e n th is e f f e c t h a s b e e n c o n firm e d in m an y c ro p ,
g ra s s , o r n a m e n ta l, w e e d , a n d n a tiv e p la n t s e e d s (Lang, 1965; A O SA , 1984).
9
T h e re h a v e b e e n s e v e r a l a tt e m p t s to a c c o u n t fo r th e r a t h e r s p e c ific
re sp o n se o f s e e d g e rm in a tio n to d iu rn a lly a lte r n a tin g
te m p e r a tu r e s .
It is
b e lie v e d t h a t th e a c tio n o f f lu c tu a tin g t e m p e r a tu r e s is e x e r te d on th e em b ry o
by in c re a s in g its g ro w th p ro c e s s e s to th e e x te n t t h a t i t c a n r u p tu r e th ro u g h th e
su rro u n d in g s tr u c tu r e s ; a f e a t th e em b ry o is in c a p a b le o f d o in g u n d e r a re g im e
o f c o n s ta n t te m p e r a tu r e s .
T r e a tm e n ts w h ich c h a n g e th e p h y s ic a l p r o p e r tie s o f
th e c o a ts or t r e a tm e n ts w h ich re m o v e th e se e d c o a t a lto g e th e r g e n e ra lly r e s u lt
in th e loss o f th e s p e c ific r e q u ir e m e n t fo r d iu rn a l t e m p e r a tu r e f lu c tu a tio n s .
S eed g e rm in a tio n , t h e r e f o r e , c a n ta k e p la c e o v e r a r e la tiv e ly w id e ra n g e of
c o n s ta n t te m p e r a tu r e s (H a rrin g to n , 1923; M o rin a g a , 1926).
T h e e f f e c t o f te m p e r a tu r e f lu c tu a tio n s is one of th o se in s ta n c e s w h e re it
is d if f ic u lt to sa y w h e th e r and to w h a t e x te n t d o rm a n c y is b e in g a f f e c te d .
In
c o m m o n c a t t a i l and b e rm u d a g ra s s , th e e f f e c t o f a lte r n a tin g te m p e r a tu r e c a n be
c la s s if ie d as th e re m o v a l o f a d o rm a n c y c o n d itio n (M orinaga, 1926; L an g , 1965).
H o w e v e r, s e e d s o f c a r r o t, tim o th y , aw n le ss b ro m e g ra s s , and s e v e r a l kinds o f
flo w e r s e e d s a tt a in h ig h g e rm in a tio n p e r c e n ta g e s w ith b o th c o n s ta n t and d iu rn a l
t e m p e r a tu r e
f lu c tu a tio n s
(H a rrin g to n ,
1923).
T he
e ffe c t
of
te m p e r a tu r e
a lt e r a t io n d o es n o t a c tu a lly re m o v e th e s p e c if ic b lo ck s to g e rm in a tio n , b u t
in s te a d p ro v id e s an in c r e a s e o f th e g e n e ra l p h y sio lo g ic a l a c ti v it y le v e l o f th e
s e e d (Lang, 1965).
S a tis f a c to r y g e rm in a tio n p e r c e n ta g e s c a n b e o b ta in e d w ith a lte r n a tin g
re g im e s o f 2 0 -3 OC o r 1 5 -2 5 C .
Som e su g g e st t h a t b o th th e h ig h e r and lo w er
t e m p e r a t u r e should a c t a t le a s t fo r p e rio d s b e tw e e n 4.5 and 8 h o u rs p e r d a ily
c y c le
(M orinaga, 1926), w h ile o th e rs a rg u e
th a t
fa v o ra b le e f f e c t s
can be
p ro d u c e d as w e ll by t e m p e r a tu r e c h a n g es w ith o u t a d e fin ite o r d a ily a lte r a tio n
(H a rrin g to n , 1923; R o lle r, 1972).
F u r th e r r e s e a r c h s u p p o rte d b o th a rg u m e n ts
10
a n d found t h a t le n g th and n u m b e r o f th e th e rm o p e rio d
d e p e n d e n t upon
te m p e r a tu r e
th e
c h a r a c te r is t ic
f lu c tu a tio n s
s p e c ie s .
p ro d u c e s th e
best
E x p o su re
c y c le s a re h ig h ly
o f se e d
g e rm in a tio n
r e s u lts
to
d iu rn a l
w hen th e
t e m p e r a tu r e d if f e r e n tia ls a re a t le a s t te n d e g re e s o r g r e a t e r b e tw e e n th e u p p e r
a n d lo w e r lim its (H a rrin g to n , 1923; L an g , 1965; R o lle r, 1972).
T he o p tim u m u p p e r g e rm in a tio n te m p e r a tu r e o f s p e c ie s is 30C ; h o w e v e r,
in c e le ry it s e e m s to b e 3 2 0 , an d in jo h n so n g ra ss 4 5 C . F ew s e e d s a re c a p a b le o f
g e rm in a tin g a t t e m p e r a tu r e s b e lo w I SC (B ew ley and B la c k , 1985).
P r e c h ill
Low
t e m p e r a tu r e s h a v e
o v e rc o m in g d o rm a n c y .
f re q u e n tly b e e n m e n tio n e d as. a m e th o d
fo r
M any s p e c ie s , p a r tic u la r ly th e ro se fa m ily and w oody
s p e c ie s , a re n o t c a p a b le o f g e rm in a tin g u n til e x p o sed to f re e z in g te m p e r a tu r e s .
G e n e ra lly , p re c h illin g o c c u rs b e tw e e n I a n d IOC w ith th e f a s t e s t r e s u lts
o b ta in a b le b e tw e e n 2 a n d SC (B ew ley and B la c k , 1982).
T h e le n g th o f th e
c h illin g p e rio d is in d e p e n d e n t am o n g s p e c ie s and m ay la s t a few d ay s to s e v e ra l
m o n th s.
In o rd e r fo r th e s e e d s to resp o n d to th e cool t e m p e r a tu r e s , th e y m u st
b e in th e im b ib ed c o n d itio n (V illiers, 1972).
P r e c h illin g is a d v a n ta g e o u s fo r a ra n g e o f d o rm a n c y ty p e s .
C hanges have
b e e n found to o c c u r in Seed c o a ts t h a t r e s t r i c t th e g e rm in a tio n o f th e em b ry o
(S te in b a u r, 1937; V illie rs and W areing, 1964 a n d 1965; W ebb a n d W arein g , 1972).
T his is th o u g h t to b e due to th e em b ry o a c q u irin g g r e a t e r v ig o r d u ring th e
c h illin g p e rio d w h ich e n a b le s it to o v e rc o m e th e r e s is ta n c e im p o s e d b y th e se e d
c o a t s tr u c tu r e s (V illiers and W arein g , 1965). T h e p e rio d o f low te m p e r a tu r e s is
m o re e f f e c ti v e fo r F ra x in u s s e e d s if it is p r e c e d e d f ir s t b y a p e rio d o f w arm
11
te m p e r a tu r e .
F ra x in u s e m b ry o s a re im m a tu r e an d m u st go th ro u g h th is p e rio d
o f w arm te m p e r a tu r e to d e v e lo p . T he s u b s e q u e n t a d d itio n o f low te m p e r a tu r e s
is n e c e s s a ry fo r re m o v a l o f th e r e s tr ic tio n s im p o se d by its s e e d c o a t.
T he a d d itio n o f low te m p e r a tu r e s h a s b e e n found to in c r e a s e m a rk e d ly th e
en d o g e n o u s c o n c e n tr a tio n o f GA (V illiers and W arein g , 1965). O rig in a lly i t w as
b e lie v e d t h a t th e in h ib ito rs d e c re a s e d o r d is a p p e a re d d u rin g th e c h illin g p e rio d
e n a b lin g s e e d s to g e rm in a te .
S u b se q u e n t s tu d ie s (F ra n k la n d a n d W arein g , 1962;
C hen an d V a rn e r, 1973) found th e c o n c e n tr a tio n o f g e rm in a tio n p ro m o te rs
in c r e a s e d
m a rk e d ly .
C h ille d h a z e l s e e d s h a d a 200 tim e in c r e a s e in GA
c o n c e n tra tio n o v e r n o n c h ille d s e e d s (Ross a n d B ra d b e e r, 1968).
T his in c r e a s e
o c c u rs p r im a rily a t th e en d o f th e c h illin g p e rio d an d a f t e r th e se e d s a re
tr a n s f e r r e d to th e ir n o rm a l g e rm in a tin g te m p e r a tu r e s .
M any o th e r c h a n g e s a re r e p o r te d to o c c u r d u rin g p re c h illin g , in clu d in g
in c r e a s e s in a c id ity , c h a n g e in lipid o r g a n iz a tio n , tr a n s f e r o f food re s e rv e s to
th e e m b ry o , c h a n g e s in e n z y m e a c tiv ity , w a te r h o lding c a p a c ity , re d u c tio n in
su g a rs and r e s p ir a to r y r a t e (V illiers, 1972; C h en and V a m e r, 1973; B ew ley and
B la c k , 1982).
L ig h t
T h e lig h t r e q u ir e m e n t fo r se ed s is a g e n e tic f a c to r (E v e n a ri, 1965),
m a tu r ity m o st s e e d s h a v e a s tro n g lig h t r e q u ir e m e n t.
At
Som e s p e c ie s m a in ta in
th is r e q u ir e m e n t th ro u g h o u t th e ir e n tir e lif e c y c le ; b u t fo r m o s t, th e lig h t
r e q u ir e m e n t
can be
d im in ish e d o r e lim in a te d
w ith p ro lo n g e d
d ry
s to ra g e
(E v e n a ri, 1965; R o lle r, 1972).
S eed d e v e lo p m e n t and g e rm in a tio n c a n b e r e s t r i c t e d b y th e e m b ry o 's
su rro u n d in g
s tr u c tu r e s .
I rr a d ia tio n c a n o v e rc o m e th e m e c h a n ic a l r e s tr ic tio n
12
im p o se d by th e s tr u c tu r e s . T h e e m b ry o , b e in g th e p rim a ry s ite o f a c tio n fo r th e
p ro m o tiv e e f f e c t o f lig h t, s e c r e te s c y to ly tic e n z y m e s w hen ir r a d ia te d (E v en ari,
1965; S c h e ib e an d L an g , 1965; R o lle r, 1972; B ew ley and B la c k , 1985).
T h e se
e n z y m e s c a u se a w e a k e n in g o f c e ll m e m b ra n e s allow ing e m b ry o d e v e lo p m e n t
a n d su b se q u e n t g e rm in a tio n .
T h e re h a v e also b e e n s u g g e stio n s t h a t lig h t-
s e n s itiv ity m ay b e lin k ed to g a s e x c h a n g e (Ikum a and T h im a n n , 1963; E v e n a ri,
1965). T his h a s b e e n found to b e tr u e in s e e d s o f ev e n in g p rim ro s e . An in c re a s e
in
r e s p ir a tio n
o c c u rre d
w ith
ir r a d ia te d
seeds
th a t
e q u a lle d
th e
ris e
in
r e s p ir a tio n w hen th e s e e d c o a t w as p ric k e d or c o m p le te ly r e m o v e d (S iegel,
1950).
T his g a v e im p e tu s to th e n o tio n t h a t
irr a d ia tio n is e f f e c tiv e v ia a
w e a k e n in g o f c e ll m e m b ra n e s o f su rro u n d in g s tr u c tu r e s .
T h is w e a k e n in g , in
tu rn , allo w s an in c r e a s e in g a s e x c h a n g e to th e e m b ry o ; th e r e b y p ro m o tin g th e
g e rm in a tio n p r o c e s s (es) (S iegel, 1950; Ik u m a a n d T h im an n , 1963; E v e n a ri, 1965;
S c h e ib e and L a n g , 1965; B ew ley and B la c k , 1985).
T he p ro m o tiv e e f f e c t o f lig h t is c o n tro lle d b y a p h o to re v e rs ib le p ig m e n t
c a lle d p h y to c h ro m e (E v e n ari, 1965; H e n d ric k s an d T a y lo rso n , 1967; R o lle r,
1972; B ew ley and B la c k , 1985). P h y to c h ro m e e x is ts in tw o fo rm s: p h y to c h ro m e
r e d (PR) and p h y to c h ro m e f a r - r e d (PER ).
T he p h y sio lo g ic a lly a c tiv e form is
P F R w h ich is in v o lv e d in th e b re a k in g o f d o rm a n c y .
I rr a d ia tio n w ith r e d lig h t r e s u lts in a c o n v e rsio n o f in a c tiv e P R to a c tiv e
PFR.
D u rin g th is c o n v e rs io n a s e rie s o f e v e n ts a re tr ig g e re d t h a t e v e n tu a lly
le a d to th e e lim in a tio n o f d o rm a n c y and th e o n s e t o f g e rm in a tio n (C opeland,
1976; B ew ley and B la c k , 1985).
I rr a d ia tio n w ith f a r - r e d lig h t r e v e r s e s th e
r e a c tio n . D o rm a n c y is m a in ta in e d b e c a u s e o f f a r - r e d lig h ts lo w e r e n e rg y s ta tu s
w h ich
cannot
p a r t i c i p a te
in
th e
r e a c tio n s
le a d in g
to
g e rm in a tio n .
W ith
13
a l t e r n a t e a p p lic a tio n s o f r e d and f a r - r e d lig h t to se e d s, th e e lim in a tio n o r
r e t e n ti o n
o f d o rm a n c y
is d e te r m in e d
by
th e
la s t
ir r a d ia tio n
fo rm
g iv en
(C o p e la n d , 1976; B ew ley an d B la c k , 1985).
T he d u ra tio n o f p h o to p e rio d fo r o b ta in in g m axim um g e rm in a tio n v a rie s
am o n g S pecies.
F id d le n e c k s e e d s (B o rth w ick e t a l, 1954) r e q u ir e s a c r i t ic a l
p h o to p e rio d o f 12 h o u rs o r less; w h e re a s e a s te r n h e m lo c k , e u ro p e a n w h ite b irc h ,
and w ood fe rn (K o ller, 1972; B askin and B ask in , 1976) re q u ire a p h o to p e rio d o f
g r e a t e r th a n 12 h o u rs.
Som e s p e c ie s do n o t re q u ire a c r i t i c a l p h o to p e rio d .
In s te a d g e rm in a tio n s te a d ily in c re a s e s as th e p h o to p e rio d d u ra tio n in c re a s e s
(E v e n a ri, 1965; B ew ley an d B la c k , 1985). G e rm in a tio n o f to m a to , c u c u m b e r and
so m e a m a r a n th u s s p e c ie s a re in h ib ite d w hen e x p o sed to a n y fo rm
(M an cin elli
et
a l,
H e n d ric k s,
1969).
1967;
D a rk
M a n cin e lli
and
g e rm in a tio n ,
T o lk o w sk y ,
1968;
lik e
g e rm in a tio n ,
lig h t
o f lig h t
T a y lo rso n
is
and
also
p h y to c h rp m e c o n tro lle d an d th e c a p a c ity fo r th e em b ry o to g e rm in a te in th e
d a rk is d e p e n d e n t upon th e s e e d s p h y to c h ro m e c o n te n t. D a rk g e rm in a tin g se e d s
c o n ta in m o re a c tiv e p h y to c h ro m e in th e ir e m b ry o th a n lig h t-r e q u ir in g se e d s
(E v e n ari, 1 9 6 5 ;.K o lle r, 1972; B ew ley and B la c k , 1985).
T e m p e r a tu r e In flu e n c e s on P h o to p e rio d .
T e m p e r a tu r e h a s th e g r e a t e s t im p a c t on a se ed s p h o to re q u ire m e n t.
As
te m p e r a tu r e v a rie s so d o es th e r e la tio n o f germ in atio n , to its p h o to p e rio d .
G e n e ra lly , a p h o to p e rio d , w h ich p ro d u c e s o p tim u m g e rm in a tio n le v e ls a t one
t e m p e r a tu r e , p ro d u c e s le v e ls w h ich a re e x c e s s iv e .a t a n o th e r (S te a rn s and O lson,
1958; E llio t and F re n c h , 1959).
T he m o st d e ta ile d s tu d y c o n d u c te d on th e
i n te r a c tio n o f t e m p e r a tu r e an d lig h t h a s b e e n w ith l e t tu c e s e e d g e rm in a tio n
(B o rth w ic k e t a l, 1954; E llio t and F re n c h , 1959; Ik u m a and T h im a n n , 1963;
14
S c h e ib e an d L a n g , 1965).
G ra n d ra p id l e t t u c e se e d s a re c a p a b le o f m ax im u m
g e rm in a tio n in t o t a l d a rk n e s s a t low te m p e r a tu r e s .
g e rm in a tio n is b e s t w ith ir r a d ia tio n .
g e rm in a tio n e n s u e s .
B e tw e e n 20C and 30C
A t te m p e r a tu r e s h ig h e r th a n 30C no
T he p re s e n c e o f high te m p e r a tu r e s g e n e ra lly r e s u lts in
d e le te r io u s e f f e c t s w ith m o st se e d s.
T h e lig h t re sp o n se is su c h t h a t it c a n
o v e rc o m e so m e o f th e in ju rio u s e f f e c ts and p ro m o te g e rm in a tio n (S iegel, 1950;
R o lle r, 1972).
W here
in c r e a s e s
in
te m p e r a tu r e
p h o to re q u ire m e n t fo r l e t tu c e
cucum ber
te m p e r a tu r e
se e d
in c r e a s e s
c a u se s
g e rm in a tio n ,
r e s u lts
in
an
an
in c r e a s e
in s e e d s
escape
in
o f to m a to
fro m
th e
and
p h o to c o n tro l
(M an cin elli e t a l, 19,67; M a n c in e lli and T o lk o w sk y , 1968) . M e a su ra b le in c re a s e s
in p h y to c h ro m e d u rin g d a rk g e rm in a tio n o f c u c u m b e r se e d s h a s b e e n c ite d and
th a t
th e
ra te
o f th is
in c r e a s e
is te m p e r a tu r e
dependent
(M an cin elli
and
T o lk o w sk y , 1968). A t h ig h e r te m p e r a tu r e s , le ss P F R s e e m e d to b e re q u ire d fo r
g e rm in a tio n .
It is n o t e s ta b lis h e d , y e t, if th is is due to th e a c tiv a tio n o f a
s y s te m d if f e r e n t fro m p h y to c h ro m e o r to a n in c r e a s e d r a t e o f p h y to c h ro m e
r e a c tio n .
T he n u m b e r o f p h o to p e rio d s r e q u ire d to tr ig g e r se ed g e rm in a tio n c h a n g es
d r a m a tic a lly w ith t e m p e r a tu r e .
e lim in a te
Low t e m p e r a tu r e s c a n re d u c e o r c o m p le te ly
m o st s e e d s r e d lig h t r e q u ir e m e n t b y d e la y in g o r p re v e n tin g th e
tr a n s f o r m a tio n o f P F R to P R , th u s m ak in g d a rk g e rm in a tio n p o ssib le fo r lig h tr e q u irin g s e e d s (S iegel, 195,0; S te a rn s and O lson, 1958; E v e n a ri, 1965; S chiebe
an d L an g , 1965).
g e rm in a tio n
t e m p e r a tu r e s .
S e v e ra l e x p o su re s to lig h t n e c e s s ita te th e in itia tio n o f th e
p ro c e s s e s
w hen
th e s e
seeds
a re
p r e c o n d itio n e d
E u ro p e a n w h ite b irc h s e e d s a re an e x c e p tio n .
at
h ig h e r
T hey becom e
m o re lig h t s e n s itiv e th e lo n g e r th e y a re e x p o se d to m o ist c h illin g . S e v e ra l long
15
e x p o s u re s to lig h t in te r r u p te d by d a rk p e rio d s is n e c e s s a ry fo r te r m in a tin g
d o rm a n c y .
A t h ig h e r te m p e r a tu r e s th e s e e d s lig h t r e q u ir e m e n t is s till p r e s e n t;
b u t on ly a sin g le e x p o su re to lig h t, e ith e r long o r s h o rt, is n e c e s s a ry to s t a r t th e
c h a in o f g e rm in a tio n p ro c e s s e s (B ew ley a n d B la c k , 1985)
16
CH APTER n
TE T R A Z O L IU M VIABILITY P R O C E D U R E S F O R
SIX NATIVE RA N G E SPECIES
In tro d u c tio n
T he in c re a s in g d is tu rb a n c e o f la rg e a c re a g e s due to s u rf a c e m ining h a s
in c r e a s e d th e c o m m e rc ia l sa le o f n a tiv e s p e c ie s se e d fo r r e c la m a tio n . V ia b ility
te s tin g o f th is se e d h a s n o t b e e n p r a c t ic a l due to th e la c k o f know n te s tin g
p r o c e d u re s .
T he n e e d fo r a r a p id m e th o d to a sse ss v ia b ility h a s le d to th e in tro d u c tio n
and a c c e p ta n c e o f s ta in in g se e d w ith 2 ,3 ,5 - t r ip h e n y l- 2 H - te t r a z o Iium c h lo rid e
(TZ) (S m ith and T h ro n e b e rry , 1951; D e lo u c h e e t ail., 1962; M o o re, 1969). S eeds
th a t
a re
d if f ic u lt
to
te s t
w ith
c o n v e n tio n a l g e rm in a tio n
p ro c e d u re s h a v e
s u c c e s s fu lly b e e n e v a lu a te d fo r v ia b ility u sin g th e TZ te c h n iq u e .
O ur o b je c tiv e
w as to d e v e lo p TZ te c h n iq u e s fo r six s p e c ie s : A c h ille a m ille fo liu m L- (Y arrow );
A g ro p y ro n s p ic a tu m
s a n d re e d );
E ly m u s
(B luebunch w h e a tg ra s s ); C a la m o v ilfa lo n g ifo lia (P ra irie
c in e re u s
(Basin
w ild ry e );
R a tib id a
c o lu m n ife ra
(P ra irie
c o n e f lo w er); S porobolus a iro jd e s (A lkali s a c a to n ). C o r r e la tio n s b e tw e e n s p e c ific s ta in in g p a tt e r n s and a c tu a l g e rm in a tio n
c a n only b e o b ta in e d a f t e r c o n s id e ra b le t e s tin g e x p e rie n c e .
o b je c tiv e o f th is p a p e r to p ro v id e th is in fo rm a tio n .
I t is n o t th e
17
M a te ria ls and M e th o d s
S eed s a m p le s w e re c o n tr ib u te d by v a rio u s se e d c o m p a n ie s v a ry in g in
g e o g ra p h ic a l lo c a tio n . S e e d lo ts v a rie d in a g e fro m one to s e v e n y e a rs .
Tw o r e p lic a te s o f 100 s e e d s w e re u se d fo r te tr a z o liu m (TZ) v ia b ility t e s ts .
S e e d s w e re p r e c o n d itio n e d b y p la c in g in b e a k e rs fille d w ith ta p w a te r or
b e tw e e n b l o tt e r s m o is te n e d w ith ta p w a te r . S eed s w e re p re c o n d itio n e d a t room
te m p e r a tu r e fo r 4 to 16 h o u rs. L e n g th o f w a te r so ak p rio r to TZ s ta in in g is n o t
o f te n
c r i t ic a l
to
s u c c e s s fu l s ta in in g ,
and
c a n be
a d ju s te d
fo r
la b o ra to ry
c o n v e n ie n c e .
P r e p a r a tio n o f th e s e e d s in v o lv ed b is e c tin g b lu eb u n c h w h e a tg ra s s and
b a sin w ild ry e lo n g itu d in a lly and p r a ir ie s a n d re e d h o riz o n ta lly u sin g d is s e c tin g
k n iv e s.
T h e se e d c o a t o f y a rro w w as p ie r c e d w ith a n e e d le , w h e re a s , th e se e d
c o a t o f p r a ir ie co n e flo w e r w as c o m p le te ly re m o v e d .
A lk ali s a c a to n se ed s w e re
p r e p a r e d fo r s ta in in g b y m e c h a n ic a l s c a r if ic a tio n w ith a F o r s b e r g la b o ra to ry
s c a r if ie r , fo r 0, I , 2, a n d 3 se c o n d s b e fo r e p re c o n d itio n in g b e tw e e n m o ist
b l o tt e r s .
A s te r e o s c o p ic m ic ro sc o p e w ith 10 and 20 p o w e r m a g n ific a tio n and
to p and b o tto m illu m in a tio n w as u se d to aid in p r e p a r a tio n an d in te r p r e ta tio n .
T h e p r e p a r a tio n m e th o d s u s e d w e re s im ila r to th e g u id elin e s a s o u tlin e d in th e
T e tra z o liu m T e s tin g H an d b o o k (G rab e, 1970).
A f te r
p r e p a r a tio n ,
c o v e re d w ith TZ so lu tio n .
seeds
w e re
p la c e d
in
S y ra cu se
w a tc h g la s s e s and
S eeds w e re s ta in e d in th e d a rk a t 3 2 C . T e tra z o liu m
s o lu tio n s w e re p r e p a r e d u sin g 2 ,3 ,5 -trip h e n y l-2 H -te tr.a z o liu m c h lo rid e (S m ith,
1951; G ra b e , 1959 an d 1970). a t c o n c e n tra tio n s o f:
a n d 1.0% fo r i n ta c t s e e d s and e m b ry o s.
0.1% fo r b is e c te d em b ry o s
D u ra tio n o f TZ so a k ra n g e d fro m 3
h o u rs to 56 h o u rs, d e p e n d in g on th e s p e c ie s .
U pon c o m p le tio n o f s ta in in g , th e
18
s e e d c o a ts o f y a rro w an d a lk a li s a c a to n w e re c le a re d using IactO p h en o l so lu tio n .
S eeds w e re a llo w e d to c le a r fo r a m inim um o f one h o u r a t 7C . T e tra z o liu m w as
re m o v e d
w ith
p i p e t te
and
b lo ttin g
paper
b e fo re
c o v e rin g
seeds
w ith
la c to p h e n o h
R e s u lts and D isc u ssio n
T e tra z o liu m T e s tin g P r o c e d u re s
Y a rro w .
(T able I ) .
TZ
S eed s w e re p re c o n d itio n e d b e tw e e n m o ist b l o tt e r s o v e rn ig h t
S eed c o a ts w e re p u n c tu re d a t th e b ro a d d is ta l en d and p la c e d in 1%
fo r e ig h t h o u rs.
S eed s ta in e d fo r six h o u rs o r less w as u n d e rs ta in e d . M inor
c h a n g e in s ta in in g in te n s ity r e s u lte d fro m e x te n d in g th e s ta in in g tim e to 12
h o u rs.
S eed c o a ts n e e d to b e c le a re d w ith la c to p h e n o l s o lu tio n fo r a m inim um
o f one h o u r to a id in in te r p r e ta t io n (T able 2).
S ta in e d y a rro w se ed s w e re
i n te r p r e te d as a d ic o ty le d o n .
B lu eb u n ch W h e a tg ra s s .
S eed s w e re p re c o n d itio n e d by so a k in g in w a te r or
b e tw e e n m o is t b l o tt e r s (T able I).
lo n g itu d in a lly .
A f te r p re c o n d itio n in g , s e e d s w e re b is e c te d
O p tim u m s ta in in g o c c u rre d w hen o n e -h a lf o f e a c h se e d w as
p la c e d in 0.1% TZ fo r fo u r h o u rs.
U n d e rs ta in in g o c c u rre d w hen b lu eb u n c h
w h e a tg ra s s s e e d s w e re s ta in e d fo r le ss th a n th r e e h o u rs.
o f s ta in in g r e s u lte d in o v e rs ta in in g .
S e v e n h o u rs or m ore
L a c to p h e n o l is n o t n e e d e d b e c a u s e a
b is e c te d s u rf a c e o f th e e m b ry o is e x p o sed fo r i n te r p r e ta tio n (T able 2). S ta in e d
b lu e b u n c h w h e a tg ra s s s e e d s w e re i n te r p r e te d as a m o n o c o ty le d o n .
P r a ir ie S a n d re e d .
S eed s w e re p re c o n d itio n e d by p la c in g b e tw e e n m o ist
b l o tt e r s o v e rn ig h t (T a b le I ).
L o n g itu d in a l b is e c tin g w as im p o ssib le due to th e
19
ob lo n g sh a p e o f th e se e d .
S eed s w e re b is e c te d h o riz o n ta lly a t th e p e rip h e ry o f
th e e m b ry o a f t e r th e s e e d c o a t w as re m o v e d . T he e m b ry o n ic a x is w as p la c e d in
1% TZ fo r 10 to 16 h o u rs (o v ern ig h t). In sig n ific a n t c h a n g e o c c u rr e d in s ta in in g
in te n s ity b e tw e e n 10 and 24 h o u rs.
h o u rs.
O p tim u m TZ s ta in in g ra n g e d fro m 10 to 24
T he s ta in in g tim e u se d w ould d e p e n d u p o n c o n v e n ie n c e in la b o ra to ry
ro u tin e .
L a c to p h e n o l is n o t n e c e s s a ry fo r i n te r p r e ta t io n (T able 2).
S ta in e d
p r a ir ie s a n d re e d s e e d s w e re in te r p r e te d as, a m o n o c o ty le d o n .
B asin W ild ry e . S eed s w e re p re c o n d itio n e d by so ak in g in w a te r or b e tw e e n
m o is t
b lo tte r s
(T able
I ).
A f te r
p re c o n d itio n in g ,
seeds
w e re
b is e c te d
lo n g itu d in a lly and o n e -h a lf o f e a c h se e d w as p la c e d in 0.1% TZ fo r fo u r h o u rs.
L ess th a n th r e e h o u rs r e s u lte d in u n d e r s ta in in g o f e m b ry o s, w h e re a s , se v e n
h o u rs o r lo n g e r r e s u lte d in o v e rs ta in in g .
L a c to p h e n o l is n o t n e e d e d b e c a u s e a
b is e c te d s u r f a c e o f th e e m b ry o is e x p o sed fo r i n te r p r e ta t io n (T able 2). S ta in e d
b a s in w ild ry e s e e d w e re in te r p r e te d as a m o n o c o ty le d o n .
P r a ir ie C o n e flo w e r. S eeds w e re p r e c o n d itio n e d by p la c in g b e tw e e n m o ist
b l o tt e r s o v e rn ig h t (T able I).
A f te r p re c o n d itio n in g , th e se e d c o a t w as re m o v e d
by a p p ly in g p re s s u re a t th e b ro a d , d is ta l en d o f th e se e d .
e m b ry o o u t o f th e se e d c o a t.
T his fo rc e s th e
T he em b ry o w as th e n p la c e d in 1% TZ fo r fo u r
h o u rs. T his p ro c e d u re w ill d a m a g e th e tip .o f th e c o ty le d o n and m u st b e ig n o re d
w h en in te r p r e tin g th e s ta in in g .
S eeds w e re u n d e rs ta in e d w h en s o a k e d in TZ fo r
tw o h o u rs o r le ss. G r e a te r th a n se v en h o u rs o f s ta in in g o v e rs ta in e d th e e m b ry o .
No la c to p h e n o l s o lu tio n is n e c e s s a ry fo r in te r p r e ta t io n o f s ta in e d se e d (T able 2).
S ta in e d p r a ir ie co n e flo w e r se e d s w e re i n te r p r e te d as a d ic o ty le d o n .
20
A lk a li S a c a to n .
T his s p e c ie s h a s a h ig h p e r c e n ta g e o f h a rd se e d and
should b e s c a r if ie d fo r tw o se c o n d s w ith a m e c h a n ic a l s c a r i f i e r in o rd e r fo r
s e e d s to s ta in w ith TZ (T able 3). S c a rifie d s e e d W ere p re c o n d itio n e d o v e rn ig h t
b e tw e e n
m o is t
s c a r if ic a tio n ,
b l o tt e r s
s ta in in g
and
tim e
p la c e d
needs
to
in
1%
TZ
fo r
24
h o u rs.
W ith o u t
b e in c r e a s e d to 48 h o u rs (T able 4).
S w elling o f s e e d c o a t, g e n e ra lly , did n o t o c c u r u n til 20 h o u rs o f TZ s ta in in g w ith
s c a r if ie d se e d and 40 h o u rs w ith n o n s c a rifie d se e d .
o b se rv e d a t b o th s ta in in g tim e s .
R a d ic le p r o tru s io n w as
A lk a li s a c a to n se e d co u ld h o t b e b is e c te d
b e c a u s e o f th e p r e s e n c e o f a m u c ila g e n o u s com p o u n d t h a t is p r e s e n t on w e t
s e e d s and due to th e s iz e and s h a p e o f th e s e e d (T able I).
c le a r e d w ith la c to p h e n o l fo r a p p ro x im a te ly one h o u r.
S ta in e d s e e d w as
C le a rin g p e r m itte d
in te r p r e ta t io n o f s ta in in g w ith th e a id o f m a g n ific a tio n and u sin g to p and
b o tto m illu m in a tio n (T able 2).
w as i n te r p r e te d as a dicotyledon*
S ta in e d b u t u n g e rm in a te d a lk a li s a c a to n se ed
T a b le I . T e tra z o liu m v ia b ility p ro c e d u re s fo r six n a tiv e ra n g e sp e cie s.
TZ Cone.
TZ S tain *
(H o u r s )
S p e c ie s
P reco n d itio n
P re p a ra tio n
(%)
Y arrow
B e tw e e n m oist
b lo tte rs o v e rn ig h t* *
P u n c tu re
seed coat
I
S o a k in w a t e r * * *
dr
b e tw e e n m oist
b lo tte r s o v ern ig h t
B isect
lo n g itu d in a lly
0.1
4
P ra irie
sandreed
B e tw e e n m oist
b lo tte rs o v ern ig h t
B isect
la te ra lly
I
10
or
overn ig h t
B asin
w ild ry e
S o a k in w a t e r
or
b e tw e e n m oist
b lo tte rs o v ern ig h t
B isect
lo n g itu d in a lly
0.1
4
B e tw e e n m oist
b lo tte rs o v ern ig h t
Rem ove
seed coat
I
4
I
24
I
48
B lu eb u n ch
w h eatg rass
P ra irie
co n eflo w er
A lk ali
sacato n
* a t 32C
B e tw e e n m oist
b lo tte rs o v ern ig h t ;
M ech. sc a rif.
Z seconds
or
O seconds
** a p p ro x im a te ly 16 h o u rs
.
R em arks
8
R em o v e o u te r
co verings
M uciIag en o u s seed coat
* * * a p p ro x im a te ly 4 hours
C le a r I h o u r w ith
la c to p h e n o l
T a b le 2. P e r c e n ta g e v ia b ility , e f f e c t of la c to p h e n o l, e f f e c t of se ed c o a t p r e p a r a tio n on s ta in in g ,
and te tr a z o liu m s ta in in g tim e e v a lu a tio n for six n a tiv e ra n g e sp e c ie s.
TZ
V ia b ility
S p ecies
(%)
Y arrow
1977
1988
94%
. 65%
B lu eb u n ch w h e a tg ra s s
1980
1981
'1 9 8 2
88%
85%
B asin w ild ry e
1980
1981
1982
90%
94%
72%
A lk ali s a c a to n
19 8 1NK
1981JK
* P o s itiv e (+) e f f e c t
U n d e rsta in
O p tim u m
+*
-
6
8
+
3
4
O v erstain
NO * * *
7
■. v '
-
1982
' P ra irie co n eflo w er
1981
1983
S ta i n e d W ith S eed
C oat In tact
61%
88%
91%
P r a i r i e s a n d r e e 'd
1978
1980
S t a i n T i m e (hrs)
L a c to p h e n o l
E ffect
8
10
'
NO
64%
-
+
3
4
7
-
-
2
4
8
4-
slow
24-48
NO
.
89%
85%
20 .
70%
7d%
** N e g a tiv e (-) e f f e c t
* * * NC = No ch an g e w ith in c re a s e d s ta in in g tim e
23
T a b le 3. P e r c e n ta g e v ia b ility , d e te r m in e d by TZ s ta in in g , fo r fo u r s c a r if ic a tio n
t r e a tm e n ts w hen a v e ra g e d o v e r tw o a lk a li s a c a to n s e e d lo ts . S eed s w e re TZ
s ta in e d fo r 24 h o u rs.
S c a r if ic a tio n
T r e a tm e n ts
(Seconds) ■
P e r c e n ta g e V ia b ility
24 -Hours TZ S ta in in g
(%)
0
I
2
3
LSD
48 a
59 b
72 c
61 b
3.32
M eans in c o lu m n fo llo w e d by l e t t e r s in c o m m o n a re n o t s ig n if ic a tly d if f e r e n t a t
th e 5% le v e l o f p ro b a b ility .
T a b le 4. P e r c e n ta g e v ia b ility a t 0 an d 2 se c o n d s o f s c a r if ic a tio n w ith TZ
s ta in in g tim e . P e r c e n ta g e s a re th e a v e ra g e o f tw o a lk a li s a c a to n s e e d lo ts .
P e r c e n ta g e V ia b ility
TZ S ta in in g
(Hours)
8
16
24
36
48
LSD
S c a rif ic a tio n T r e a tm e n ts (Seconds)
—----------------------;-------------- :---------------0
2
la
15 b
50 c
57 d
72 e
4.59
26 a
64 b
74 c
74 c
74 c
2.69
M eans in co lu m n s fo llo w e d b y l e t t e r s in c o m m o n a re n o t s ig n if ic a n tly d if f e r e n t
a t th e 5% le v e l o f p ro b a b ility .
24
CHAPTER n r
G ERM IN A TIO N P R O C E D U R E S F O R SIX .
NATIVE RA N G E SPECIES
In tro d u c tio n
A c h ille a
m ille fo liu m
L.
(Y arrow )
and
R a tib id a
c o lu m n ife ra
(P ra irie
c o n e flo w e r) a re p e re n n ia l fo rb s d is tr ib u te d in th e G r e a t P la in s and a d ja c e n t
a re a s .
Y a rro w is a co o l s e a so n p la n t t h a t h a s high p o t e n t ia l fo r alp in e and
su b a lp in e r e v e g e ta tio n , b u t its p a la tib ility is low . Y a rro w th r iv e s in co o l, m o ist
c lim a te s an d re p ro d u c e s by rh iz o m e s and s e e d s (U.S. F o r e s t S e rv ic e , 1937;
H a rrin g to n , 1964)..
P r a ir ie c o n e flo w e r is a w arm se a so n p la n t w ith sh allo w ta p r o o ts and
b ra n c h r o o ts .
B e c a u se o f its a e s th e tic q u a litie s , p r a ir ie co n e flo w e r is u se d to
v e g e ta te ro a d s id e s, r e s t a re a s , g a rd e n s , p a rk s , r e c r e a tio n a re a s and p r a ir ie s .
P r a ir ie c o n e flo w e r is a w e a k ly c o m p e titiv e s p e c ie s th a t c a n n o t t o le r a t e sh a d e
o r in te n s e g ra z in g . P a la tib ility to liv e s to c k is h ig h p rio r to h e a d in g (H a rrin g to n ,
1964).
A g ro p y ro n s p ic a tu m
(B luebunch w h e a tg ra s s ) and E ly m u s c in e re u s (Basin
w ildrye) a re c o o l-s e a s o n b u n c h g ra s s e s c o m m o n to th e w e s te r n U n ite d S ta te s .
B lu eb u n ch w h e a tg ra s s is u se d fo r se ed in g a b a n d o n e d c ro p la n d , d e p le te d ra n g e
and d is tu rb e d lan d .
T his s p e c ie s is d ro u g h t to le r a n t a n d w in te rh a rd y .
It
p ro v id e s good p a la tib le fo ra g e fo r e lk an d f a ir p a la tib le fo ra g e fo r d e e r and
I
25
liv e s to c k .
T his
s p e c ie s
is
s u p e rio r
in
fo ra g e
n u tr ie n t
v a lu e
to
c r e s te d
w h e a tg ra s s . P o o r s e e d fill and s ta n d e s ta b lis h m e n t a re th e p r im a ry lim ita tio n s
o f bluebvm ch w h e a tg ra s s (P lu m m e r e t a l, 1955).
B asin w ild ry e is a d a p ta b le to d ra in a g e b a sin s and high e le v a tio n s .
It is a
v e ry s tr o n g c o m p e tito r , w e ll s u ite d fo r d is tu rb e d soils and d ra in a g e d itc h e s .
B asin w ild ry e a lso p ro v id e s e x c e lle n t c o v e r to g a m e b ird s an d fo ra g e fo r big
g a m e a n im a ls (V a lle n tin e , 1971; Shaw and C o o p e r, 1973).
C a la m o v ilfa lo n g ifo lia (P ra irie sa n d re e d ) an d SporobOlus a iro id e s (A lkali
s a c a to n ) a re w a rm -s e a s o n , w in te rh a rd y , d ro u g h t to le r a n t s p e c ie s . N a tiv e s ta n d s
o f p r a ir ie s a n d re e d a re u se d fo r g ra z in g and h a y . P r a ir ie s a n d re e d is co m m o n ly
u se d fo r s ta b iliz a tio n o f sa n d y soils b e c a u s e o f its c o a rs e fib ro u s r o o t sy ste m
w h ich is a u g u m e n te d by rh iz o m e s (Shaw and C o o p e r, 1973).
A lk ali s a c a to n h a s a d e n se fib ro u s r o o t s y s te m t h a t is id e a l fo r u se in
e ro sio n c o n tro l.
It p ro v id e s c o v e r and food fo r b ird s and s m a ll m am m a ls.
A lk a li s a c a to n h a s a v e ra g e p a la tib ility fo r liv e s to c k , When g re e n .
A lkali
s a c a to n is h ig h ly s a lt t o le r a n t (L e ith e a d e t a l, 1971; V a lle n tin e , 1971).
N e ith e r th e A s s o c ia tio n o f O f f ic ia l S eed A n a ly sts n o r th e I n te r n a tio n a l
Seed
T e s tin g
A s s o c ia tio n
have
e s ta b lis h e d
m e th o d s
fo r
la b o r a to r y
seed
g e rm in a tio n te s tin g o f th e s e sp e c ie s .
M a te ria ls and M e th o d s
Tw o s e e d lo ts e a c h o f a lk a li s a c a to n , p r a ir ie c o h e flo w e r, an d y a rro w ; and
th r e e s e e d lo ts e a c h o f b lu e b u n c h w h e a tg ra s s , b a sin w ild ry e , a n d p r a ir ie sa n d ­
r e e d w e re e v a lu a te d .
S e e d lo ts ra n g e d fro m o n e - to s e v e n -y e a rs o ld . F o u r 1 00-
.26
s e e d r e p lic a tio n s o f e a c h s e e d lo t w e re te s t e d fo r e a c h t r e a t m e n t .
w e re s e le c te d
a t ra n d o m
w ith o u t r e g a r d
T he se e d s
to s iz e o r c o lo r, b u t only
fu lly
d e v e lo p e d , u n d a m a g e d s e e d s w e re te s te d .
S e e d lo ts o f th e s e six s p e c ie s w e re m o ist p re c h ille d fo r 0, 5 an d 10 d ays a t
SC.
2 0C ,
A f te r p re c h illin g , s e e d lo ts w e re g e rm in a te d a t c o n s ta n t te m p e r a tu r e s o f
25C ,
and 3 0 C , an d a t an a lte r n a tin g te m p e r a tu r e
o f, 1 5-25C .
T he
a lte r n a tin g te m p e r a tu r e w as p ro g ra m m e d fo r a d a ily c y c le o f 16 h rs, a t th e low
t e m p e r a tu r e and 8 h rs. a t th e h ig h te m p e r a tu r e .
T he lig h t t r e a tm e n ts fo r th e
a lte r n a tin g 15-25C a n d c o n s ta n t 25C te m p e r a tu r e s w e re p ro g ra m m e d fo r 16
h rs . d a rk n e s s and 8 h rs . lig h t d u rin g a 24 h r. period*
F o r th e a lte r n a tin g
g e rm in a tio n te m p e r a tu r e , th e lig h t p e rio d c o in c id e d w ith th e h ig h te m p e r a tu r e
p e rio d .
T he
t r e a tm e n ts .
c o n s ta n t
20C
te m p e r a tu r e
w as
e v a lu a te d
u sin g
tw o
lig h t
O ne lig h t t r e a tm e n t w as p ro g ra m m e d fo r 16 h rs . d a rk n e s s and 8
h rs . lig h t d u rin g a 24 h r . p e rio d . T he se c o n d lig h t t r e a tm e n t w as p ro g ra m m e d
fo r 24 h rs . o f d a rk . T he c o n s ta n t 30C t e m p e r a tu r e w as p ro g ra m m e d fo r 24 h rs.
o f lig h t.
S ta n d a rd c o o l w h ite flo u r e s c e n t tu b e s w e re u se d as th e lig h t so u rc e .
S eed s w e re p la c e d in p la s tic g e rm in a tio n b o x e s on to p o f tw o s ta n d a r d blu e
g e rm in a tio n b lo tte r s m o is te n e d w ith d is tille d w a te r .
S eeds w e re th e n p la c e d in
th e p r e c h ill c h a m b e r fo r v a rio u s tim e p e rio d s and th e n tr a n s f e r r e d to th e
g e rm in a tio n c h a m b e r.
G e rm in a tio n t e s t s w e re o rg a n iz e d so th e tw o p re c h ill
t r e a tm e n ts and th e c o n tr o l tr e a tm e n t w e re p la c e d in th e g e rm in a to r a t th e
s a m e tim e .
"When n e c e s s a ry d u rin g g e rm in a tio n , b o x es w e re w a te re d w ith
d is tille d w a te r .
G e rm in a tio n t e s t s w e re c o n d u c te d fo r 38 d a y s. C o u n ts w e re m a d e w eek ly
d u rin g th e f ir s t m o n th a n d a t five d a y in te r v a ls , t h e r e a f t e r .
A se ed w as
c o n s id e re d g e rm in a te d w hen b o th r a d ic le and plum m ule h a d a tt a in e d a le n g th
27
o n e -h a lf th e s iz e o f th e se e d .
In th e case, o f a lk a li s a c a to n , w h e re se e d s a re
e x tr e m e ly s m a ll, s e e d s w e re c o n s id e re d a s b e in g g e rm in a te d w h en b o th ra d ic le
a n d plum m u le r e a c h e d 3 m m in le n g th .
th e g e rm in a tio n b o x e s a t e a c h c o u n t.
G e rm in a te d s e e d s w e re re m o v e d fro m
T h e se e x p e rim e n ts w e re d e sig n e d as a
ra n d o m iz e d b lo c k d e sig n .
R e s u lts and D isc u ssio n
Y a rro w
T he
v ia b ility
of
th e
1977
and
1981
r e s p e c tiv e ly , as d e te r m in e d by te tr a z o liu m
s e e d lo ts
(TZ)..
w as
94%
and
65% ,
P oor, v ia b ility o f th e 1981
s e e d lo t w as due to p o o r se e d fill and im m a tu r e e m b ry o s. Low v ia b ility m ay also
b e a s s o c ia te d w ith im p ro p e r e n v iro n m e n ta l c o n d itio n s d u rin g s e e d d e v e lo p m e n t
an d p o o r s to r a g e c o n d itio n s (B a rto n , 1961; H a rrin g to n , 1972; J u s tic e and B ass,
1978).
No a d d itio n a l g e rm in a tio n o c c u rre d a f t e r 14 d ays o f g e rm in a tio n fo r b o th
s e e d lo ts (T able 5).
S o re n se n and H old en (1974) r e p o r te d y a rro w g e rm in a tio n
o c c u re d in 2 to 8 d ay s;
O ur d a ta su g g e st t h a t m o re tim e fo r g e rm in a tio n is
n e c e s s a ry .
W hen s p e c ific g e rm in a tio n t e m p e r a tu r e s and lig h t c o m b in a tio n s w e re
e v a lu a te d le n g th o f g e rm in a tio n V aried (T able 6),
T he 20C t r e a t m e n t w ith o u t
lig h t (20C ,0L) and th e 20C w ith 8 h rs . of lig h t t r e a tm e n t (20C ,8L) w e re th e only
tw o te m p e r a tu r e a n d
g e rm in a tio n .
lig h t c o m b in a tio n s w h ich r e q u ir e d 14 d a y s to c o m p le te
A ll o th e r te m p e r a tu r e and lig h t c o m b in a tio n s r e q u ir e d se v e n d ay s.
H o w e v e r, fo r th e 1977 s e e d lo t, th e g e rm in a tio n p e r c e n ta g e s d id n o t r e f l e c t th e
28
s e e d lo t v ia b ility u n til 14 d a y s o f g e rm in a tio n h a d o c c u rre d fo r th e 20C ,8L
c o m b in a tio n (T able 7).
T his te m p e r a tu r e an d lig h t c o m b in a tio n w as th e only
t r e a t m e n t w hich e q u a lle d v ia b ility o f th e 1977 s e e d lo t.
T a b le 5.
P e r c e n ta g e g e rm in a tio n o f tw o y a rro w s e e d lo ts w ith tim e w hen
a v e ra g e d o v e r fiv e t e m p e r a tu r e and lig h t c o m b in a tio n s.
P e r c e n ta g e G e rm in a tio n
L e n g th o f G e rm in a tio n (Days)
S e e d lo ts
7
14
21
38
LSD
1977
74 a
77 b
77 b
77 b
2.39
1981
50 a
55 b
56 b
56 b
2.01
M eans in ro w s fo llo w e d by l e t t e r s in co m m o n a re n o t s ig n ific a n tly d if f e r e n t a t
th e 5% le v e l o f p ro b a b ility .
The
1 5 -2 5 C ,8 L ,
20 C ,8 L ,
and
2 5 C ,8 L
gave
th e
p e r c e n ta g e s fo r b o th s e e d lo ts a t 14 days o f g e rm in a tio n ;
h ig h e s t
g e rm in a tio n
W hereas, th e 20C ,0L
t r e a t m e n t h a d th e lo w e st p e r c e n ta g e g e rm in a tio n (T able 7).
O nly th e 20C ,8L
t r e a t m e n t e q u a lle d th e 1977 s e e d lo t's p e r c e n ta g e v ia b ility , w h e re a s th e 1525 C ,8 L ,
Z0C ,8L
and
2 5 C ,8L
had
e q u a lle d
th e
1981
s e e d lo t's
p e r c e n ta g e
v ia b ility . E d d le m a n (1979) found t h a t a f lu c tu a tin g 10-20C r e s u lte d in op tim u m
y a rro w g e rm in a tio n . O th e r r e p o r ts s t a t e 17-12C (M cD onough, 1969) a n d 2 0 -3 OC
(M aguire an d O v e rla n d ,1959) p ro v id e o p tim u m
g e rm in a tio n .
S o re n se n
and
H old en (1974) found o p tim u m g e rm in a tio n o c c u rs w ith c o n tin u o u s e x p o su re to
m o is tu re a t 2 0C .
T h e 2 0 C ,8 L tr e a tm e n t w as th e only te m p e r a tu r e and lig h t
c o m b in a tio n
r e s u lte d
th a t
in
g e rm in a tio n
p r c e n ta g e s
e q u iv a le n t
to
b o th
s e e d lo t's v ia b ility ; th e r e f o r e , i t c a n b e c o n c lu d e d t h a t o p tim u m g e rm in a tio n o f
y a rro w is o b ta in e d w ith 14 d a y s o f g e rm in a tio n a t a c o n s ta n t 20C te m p e r a tu r e
w ith 8 h rs . o f lig h t.
29
T a b le 6.
P e r c e n ta g e g e rm in a tio n o f tw o y a rro w s e e d lo ts w ith tim e w hen
g e rm in a te d a t v a rio u s te m p e r a tu r e a n d lig h t c o m b in a tio n s .
P e r c e n ta g e G e rm in a tio n
L e n g th o f
G e rm in a tio n
(Days)
1 5 -2 5 C ,8 L *
20C ,0L
20C ,8L
1977
7
14
21
38
LSD
83 a
85 a
85 a
85 a
5.18
33 a
39 b
39 b
39 b
4.71
85 a
90 b
90 b
90 b
3.35
86 a
87 a
87 a
87 a
. 2.40
80 a
82 a
82 a
82 a
2.93
1981
7
14
21
38
LSD
60 a
62 a
63 a
63 a
3.83
27 a
39 b
39 b
40 b
4.70
56 a
65 b
66 b
67 b
1.95
62 a
63 a
63 a
63 a
3.46
42 a
46 a
46 a
46 a
4.05
S e e d lo t
T e m p e r a tu r e an d L ig h t T r e a tm e n ts
25C ,8L 30 C ,2 4 L
M ean s in co lu m n s fo llo w e d by l e t t e r s in co m m o n a re n o t s ig n if ic a n tly d if f e r e n t
a t th e 5% le v e l o f p ro b a b ility .
* 8L; h o u rs o f lig h t.
T a b le 7.
C o m p a riso n o f p e r c e n t v ia b ility w ith fiv e te m p e r a tu r e an d lig h t
c o m b in a tio n 's p e r c e n ta g e g e rm in a tio n fo r tw o y a rro w s e e d lo ts .
T e m p e r a tu r e & L ig h t
T r e a tm e n ts
1 5 -2 5 C ,8 L *
2 0 C ,0 L
2 0 C ,8L
2 5 C ,8 L
30 C ,2 4 L
V ia b ility
LSD
P e r c e n ta g e G e rm in a tio n
14 D ay s o f G e rm in a tio n
:
1977
1981
85 b e
39 a
90 cd
87 b e
82 b
94 d
5.77
63 c
39 a
65 c
63 c
46 b
65 c
4.25
M eans in co lu m n s fo llo w e d b y l e t t e r s in c o m m o n a re n o t s ig n ific a n tly d if f e r e n t
a t th e 5% le v e l o f p ro b a b ility .
*8 L ; h o u rs o f lig h t
G e rm in a tio n o f y a rro w s e e d s a p p e a rs to b e p o s itiv e ly p h o to b la s tic sin c e
o p tim u m g e rm in a tio n w as a c h ie v e d w ith th e 2 0 C ,8 L tr e a tm e n t an d n o t th e
30
2 0 C ,0 L t r e a t m e n t . In c o n tr a s t to th e s e fin d in g s E d d le m a n (1979), S o re n se n and
H o ld e n (1974), and M ag u ire an d O v e rla n d (1959) r e p o r t fa v o ra b le g e rm in a tio n in
c o n tin u o u s d a rk . M cD onough (1969) r e p o r ts 8 h rs . lig h t t r e a tm e n t as o p tim u m .
P r e c h ill did n o t im p ro v e th e
g e rm in a tio n
ra te
o f y a rro w
(T able
8).
F o u r te e n d ay s w as s till th e m ax im u m tim e re q u ir e d fo r o p tim u m g e rm in a tio n o f
y a rro w , re g a r d le s s o f th e le n g th o f th e p r e c h ill t r e a tm e n t.
T a b le 8.
P e r c e n ta g e g e rm in a tio n o f th r e e p r e c h ill t r e a tm e n ts w ith tim e .
P e r c e n ta g e s a re a v e ra g e d o v e r tw o y a rro w s e e d lo ts and fiv e t e m p e r a tu r e and
lig h t c o m b in a tio n s .
P e r c e n ta g e G e rm in a tio n
P r e c h ill T r e a tm e n ts
(Days)
L e n g th o f
G e rm in a tio n
(Days)
0
5
10
7
14
21
38
LSD
63 a
68 b
69 b
69 b
L99
.6 3 a
66 b
67 b
67 b
2.49
59 a
63 b
63 b
63 b
3.30
M eans in co lu m n s fo llo w e d by l e t t e r s in c o m m o n a re n o t s ig n ific a n tly d if f e r e n t
a t th e 5% le v e l o f p ro b a b ility .
E v a lu a tio n o f in d iv id u al, s e e d lo ts a t 14 d a y s o f g e rm in a tio n show ed no
im p ro v e m e n t
in
p e rc e n t
g e rm in a tio n
w ith
t e m p e r a tu r e and lig h t c o m b in a tio n (T able 9).
p r e c h ill,
re g a r d le s s
of
th e
TheSe d a ta in d ic a te th a t.y a r r o w
d o e s n o t re s p o n d to p r e c h ill. S o re n se n and H o ld en (1974) a re in a g r e e m e n t.
31
T a b le 9.
P r e c h ill e f f e c t on tw o y a rro w s e e d lo t's p e r c e n ta g e g e rm in a tio n .
S e e d lo ts w e re g e rm in a te d a t fiv e te m p e r a tu r e a n d lig h t c o m b in a tio n s fo r 14
d a y s.
P e r c e n ta g e G e rm in a tio n
14 D ays o f G e rm in a tio n
P r e c h ill
T r e a tm e n ts
(Days)
1 5 -2 5 C ,8 L *
2 0 C ,0L
20C ,8L
1977
0
5
10
LSD
92b
90 b
73 a
12.83
42 a
41 a
33 a
11.69
94 a
87 a
89 a
7.93
89 a
86 a
87 a
5.95
81 a
82 a
82 a
7.14
1981
0
5
10
LSD
69 b
61 ab
59 a
6.12
39 ab
46 b
32 a
10.89
67 a
63 a
64 a
5.35
63 a
64 a
63 a
8.52
51 a
42 a
46 a
9.20
S e e d lo ts
T e m p e r a tu r e & L ig h t T r e a tm e n ts
2 5 C ,8 L 30C ,24L
M eans in co lu m n s fo llo w e d b y l e t t e r s in c o m m o n a re n o t s ig n ific a n tly d if f e r e n t
a t th e 5% le v e l o f p ro b a b ility .
*8L ; h o u rs o f lig h t.
B lu eb u n ch W h e a tg ra ss
T he v ia b ility o f th e 1980, 1981, an d 1982 s e e d lo ts w as 61% , 88% , and 91% ,
r e s p e c tiv e ly . M ean p e r c e n ta g e v ia b ility d e c re a s e d as s e e d lo ts in c r e a s e d in a g e .
T h e d u ra tio n fo r good v ia b ility is r e p o r te d to b e fiv e y e a rs , w h e re 85% to 90%
g e rm in a tio n
v ia b ility ,
c a p a c ity c a n b e e x p e c te d
as e x h ib ite d in th e
(H ull and P e a rs e ,
1943).
1980 s e e d lo t, m a y b e due to
T he
low
e n v iro n m e n ta l
c o n d itio n s d u rin g m a tu r a tio n , h a rv e s t d a m a g e , u n fa v o ra b le s to r a g e c o n d itio n s,
a g e in g , o r. a c o m b in a tio n o f a ll f a c to r s (H ull and P e a rs e , 1943; B a rto n , 1961;
H a rrin g to n , 1972; J u s tic e an d B ass, 1978).
C o m p a re d to s e v e n d a y s o f g e rm in a tio n , 14 days in c r e a s e d p e rc e n ta g e
g e rm in a tio n s ig n if ic a n tly fo r e a c h s e e d lo t.
T he 1982 s e e d lo t h a d th e g r e a t e s t
32
in c r e a s e in p e r c e n ta g e g e rm in a tio n (T able 10).
H a f e n r ic h te r e t a l (1968) also
r e p o r ts c o m p le te g e rm in a tio n in 14 d a y s.
T a b le 10. P e r c e n ta g e g e rm in a tio n o f th r e e bluebunC h w h e a tg ra s s s e e d lo ts w ith
tim e w hen a v e ra g e d o v e r fiv e te m p e r a tu r e an d lig h t c o m b in a tio n s .
P e r c e n ta g e G e rm in a tio n
L e n g th of
G e rm in a tio n
(Days)
1980
7
14
21
38
LSD
52 a
58 b
58 b
59 b
2.07
S e e d lo ts
.
1981
1982
78 a
84 b
84 b
85 b
1.69
64 a
86 b
88 b
88 b
3.88
M ean s in co lu m n s fo llo w e d b y l e t t e r s in c o m m o n a re n o t s ig n if ic a n tly d if f e r e n t
a t th e 5% le v e l o f p r o b a b ility .
C o m p a riso n o f s p e c if ic te m p e r a tu r e an d lig h t c o m b in a tio n s show s th e
2 0 C ,OL t r e a tm e n t r e s u lte d in th e m o st ra p id g e rm in a tio n .
T his t r e a tm e n t
c o m p le te d g e rm in a tio n w ith in 7 d a y s o f te s tin g fo r a ll s e e d lo ts (T able 11). T he
2 5 C ,8 L t r e a tm e n t c o m p le te d g e rm in a tio n in 7 d ay s b u t only fo r t h e 1980 and
1981 s e e d lo ts .
E v en th o u g h th e s e t r e a tm e n ts c o m p le te d g e rm in a tio n a t a f a s t
r a t e , th e h ig h e s t p e r c e n ta g e g e rm in a tio n fo r a ll s e e d lo ts w as o b ta in e d w ith a
t e m p e r a tu r e and lig h t t r e a tm e n t t h a t re q u ire d 14 d ay s o f g e rm in a tio n (T able
12 ) ,
T he 2 0 C ,8 L t r e a t m e n t w as th e only te m p e r a tu r e and lig h t c o m b in a tio n to
c o n s is te n tly giv e th e h ig h e s t g e rm in a tio n p e r c e n ta g e s and e q u a l p e rc e n ta g e
v ia b ility fo r a ll s e e d lo ts .
T h e re w e re o th e r te m p e r a tu r e a n d lig h t t r e a tm e n ts
t h a t g a v e e q u iv a le n t g e rm in a tio n and v ia b ility p e r c e n ta g e s b u t th e y w e re n o t
c o n s is te n t am o n g s e e d lo ts .
A f lu c tu a tin g t e m p e r a tu r e o f 2 0 -3 0 C o r 15 -3 OC w as
found to b e o p tim u m fo r H a fe rk a m p a n d M cSw ain (1951).
O ur g e rm in a tio n
33
re s p o n s e w ith th e 1 5 -2 5 C , 8L t r e a t m e n t w as e q u iv a le n t to th e c o n s ta n t 20C , 8L
t r e a tm e n t fo r th e 1981 and 1982 s e e d lo ts b u t n o t fo r th e 1980 s e e d lo t (T able
12).
T he f lu c tu a tio n o f w arm a n d cold te m p e r a tu r e s could h a v e s tr e s s e d th e
o ld e r s e e d w h ich r e s u lte d in a s ig n ific a n t r e d u c tio n in g e rm in a tio n p e rc e n ta g e s .
T a b le 11. P e r c e n ta g e g e rm in a tio n o f th r e e b lu e b u n c h w h e a tg ra s s s e e d lo ts w ith
tim e w hen g e rm in a te d a t v a rio u s te m p e r a tu r e and lig h t c o m b in a tio n s .
P e r c e n ta g e G e rm in a tio n
S e e d lo ts
L e n g th o f
G e rm in a tio n
(Days)
T e m p e r a tu r e & L ig h t T r e a tm e n ts
!
20C ,0L
20C ,8L 2 5 C ,8L
1 5 -2 5 C ,8 L *
30C ,24L
1980
7
14
21
38
LSD
29 a
36 b
37 b
37 b
4 .8 4
52 a
54 a
54 a
54 a
4.37
47 a
59 b
59 b
59 b
4.19
46 a
47 a
47 a
48 a
3.76
37 a
42 b
43 b
44 b
4.18
1981
7
14
21
38
LSD
77 a
88 b
• 88b
88 b
4.21
85 a
86 a
88 a
88 a
3.17
82 a
91 b
91 b
91 b
2.77
80 a
82 a
82 a
83 a
3.89
67 a
78 b
82 b
83 b
5,95
1982
7
14
21
38
LSD
76 a
94 b
94 b
94 b
4.27
90 a
90 a
91 a
91 a
2.11
85 a
92 b
93 b
93 b
2.95
81 a
87 b
88 b
88 b
3.33
48 a
72 b
72 b
72 b
6.12
.
M eans in co lu m n s fo llo w e d by l e t t e r s in c o m m o n a r e n o t s ig n ific a n tly d if f e r e n t
a t th e 5% le v e l o f p ro b a b ility .
* 8L; h o u rs o f lig h t
H a rrin g to n (1923) an d R o lle r (1972) c ite th e rm o d o rm a n c y is th e r e s u lt o f
s e e d b e in g e x p o sed to p ro lo n g e d p e rio d s o f ab o v e o p tim u m t e m p e r a t u r e , cau sin g
a d e c lin e in p e r c e n ta g e g e rm in a tio n .
T h e re w as a tre n d f o r th e 30C ,24L
t r e a t m e n t to b e lo w e r th a n th e r e s t o f th e t e m p e r a tu r e and lig h t c o m b in a tio n s .
W h e th e r
th is
w as a r e s u lt o f th e rm o d o rm a n c y and, o r th e
e f f e c t o f th e
34
c o n tin u o u s lig h t t r e a t m e n t , is n o t c le a r,
A c o n tin u o u s d a rk s tu d y a t th e 3 OC
te m p e r a tu r e w ould n e e d to b e c o n d u c te d to d e te r m in e th e e f f e c t o f lig h t on
b lu e b u n c h w h e a tg ra s s p e r c e n ta g e g e rm in a tio n .
T a b le 12. C o m p a riso n o f p e r c e n t v ia b ility w ith fiv e t e m p e r a tu r e and lig h t
c o m b in a tio n 's p e r c e n ta g e g e rm in a tio n fo r th r e e b lu eb u n c h w h e a tg ra s s s e e d lo ts.
P e r c e n ta g e G e rm in a tio n
14 D ay s o f G e rm in a tio n
S e e d lo ts
T e m p e r a tu r e & L ig h t
T r e a tm e n ts
1 5 -2 5 C ,8 L *
2 0 C ,0L
2 0 C ,8L
2 5 C ,8L
3 0 C ,2 4 L
V ia b ility
LSD
:
1980
1981
1982
36 a
54 d
59 e
47 c
42 b
61 e
. 4.40
88 cd
86 c
91 d
82 b
78 a
88 cd
3.67
94 c
90 be
92 b e
87 b
67 a
91 b e
5.20
,
M eans in co lu m n s fo llo w e d by l e t t e r s in c o m m o n a re n o t s ig n if ic a n tly d if f e r e n t
a t th e 5% le v e l o f p ro b a b ility .
* 8L; h o u rs o f lig h t
T he c o n tin u o u s d a rk t r e a t m e n t a t 2 0 C r e s u lte d in s ig n ific a n tly lo w er
p e r c e n ta g e g e rm in a tio n
th a n did th e 8 h rs . o f lig h t t r e a t m e n t , w ith th e
e x c e p tio n o f th e 1982 s e e d lo t (T able 12),
It is p o ssib le th e g e r m in a tio n ;t h a t
o c c u rre d d u rin g th e f ir s t w e e k w ith th e c o n tin u o u s d a rk t r e a t m e n t w as a r e s u lt
o f p h y to c h ro m e f a r - r e d (PFR) e x is tin g in th e se e d . By th e e n d o f th e f ir s t w eek
th e P F R c o n te n t w as e x h a u s te d , and g e rm in a tio n w as n o t p o ssib le d u ring th e
se c o n d w e e k (T able 11).
T h e e ig h t h o u rs o f lig h t tr e a tm e n t p ro v id e d enough
P F R to allow m ax im u m g e rm in a tio n to c o n tin u e th ro u g h th e se c o n d w eek o f
g e rm in a tio n .
H a fe rk a m p and M cSw ain (1951) h a v e found b lu e b u n c h w h e a tg ra s s
g e rm in a tio n to b e lig h t re q u irin g .
T he e n v iro n m e n t in w h ich th e se e d w as
. . 35
d e v e lo p e d arid s to r e d c a n h a v e a s ig n ific a rit e f f e c t on th e s e e d 's re q u ir e m e n t fo r
lig h t.
T his m ay e x p la in w hy th e 1982 s e e d lo t p ro d u c e d o p tim u m g e rm in a tio n
w ith th e c o n tin u o u s d a rk t r e a tm e n t.
A s e e d 's r e q u ire m e n t fo r lig h t is a g e n e tic
f a c to r w h ich c a n b e m o d ifie d by th e e n v iro n m e n t. A fa v o ra b le e n v iro n m e n t c a n
e lim in a te th e s e e d 's lig h t r e q u ir e m e n t, w h ile an u n fa v o ra b le e n v iro n m e n t c a n
s tro n g ly
a m p lify
th e
s e e d 's
lig h t r e q u ir e m e n t
(B arton
an d
G arm ari,
1946;
E v e n a ri, 1965; K o lle r, 1972; J u s tic e and B ass, 1978).
T he 2 0 C ,8 L t r e a tm e n t r e s u lte d in g e rm in a tio n p e r c e n ta g e s t h a t w e re
e q u a l to v ia b ility o f t h e s e e d lb ts , m ak in g th is te m p e r a tu r e and lig h t t r e a tm e n t
th e
o p tim u m
p ro ced u re
lig h t
fo r
g e rm in a tin g
t r e a tm e n t
b lu e b u n c h
re q u ir e d
14
d ays
w h e a tg ra s s .
to
reach
T his
te m p e r a tu r e
and
m axim um
g e rm in a tio n .
U n g e rm in a te d s e e d s re m a in in g a f t e r 14 d a y s b e c a m e m oldy.
A
c o m m o n p r a c t ic e in s e e d te s tin g la b o r a to r ie s is to c o n d u c t a te tr a z o liu m t e s t
on u n g e rm in a te d s e e d s a t th e c o n c lu sio n o f th e g e rm in a tio n p e rio d to d e te rm in e
i f th o se s e e d s a re d o rm a n t.
F o r b lu e b u n c h w h e a tg ra s s , th is t e s t should be
c o n d u c te d a t th e end o f 14 d ays o f g e rm in a tio n b e c a u s e o f th e m old p ro b le m
w h ich k ills d o rrb a n t se e d s.
T h e r e q u ir e m e n t
fo r
p re c h illin g
of
b lu eb u n c h
w h e a tg ra s s
d e p e n d e n t upon th e te m p e r a tu r e and lig h t t r e a tm e n t u se d (T able 13).
se e d
is
A t 14
d a y s o f g e rm ih a tio ri th e 2 0 C ,8 L and 15-25'C$8L t r e a tm e n ts did n o t re q u ire
p r e c h ill to p r o m o te m ax im u m g e rm in a tio n .
T en days o f p r e c h ill d id p ro m o te
m ax im u m g e rm in a tio n w ith th e o th e r th r e e te m p e r a tu r e and lig h t t r e a tm e n ts .
36
T a b le 13. P r e c h ill e f f e c t on p e r c e n ta g e g e rm in a tio n fo r fiv e te m p e r a tu r e and
lig h t c o m b in a tio n s . P e r c e n ta g e g e rm in a tio n w as a v e ra g e d o v e r th r e e b lu eb u n c h
w h e a tg ra s s s e e d lo ts .
P e r c e n ta g e G e rm in a tip n
14 D ay s o f G e rm in a tio n
P r e c h ill
T r e a tm e n t
(Days)
'
1 5 -2 5 C ,8 L *
0
5
10
LSD
71 a
73 a
73 a
4.2 2
T e m p e r a tu r e & L ig h t T r e a tm e n ts
'
'
2 SC, 8 L
20C ,0L
20 C j8 L
77 b
73 a
81 c
3.41
80 a
80 a
81 a
2.54
30C ,24L
57 a
57 a
72b
7.05
65 a
73 b
77 b
2.92
M eans in co lu m n s fo llo w e d by l e t t e r s in c o m m o n a re n o t s ig n if ic a n tly d if f e r e n t
a t th e 5% le v e l o f p ro b a b ility .
* 8L; h o u rs o f lig h t
T he g r e a t e s t in c r e a s e in p e r c e n ta g e g e rm in a tio n o c c u rre d w ith th e te n
d a y p r e c h ill t r e a tm e n t fo r th e 30C c o n tin u o u s lig h t t r e a t m e n t .
t h a t p r e c h ill d e la y e d th e o n s e t o f th e rm o d o rm a n c y .
th e
lig h t
t r e a tm e n t
m ay
have
a c te d
It is p o ssib le
T he co ld t r e a tm e n t plus
c u m u la tiv e ly ,
to
in c r e a s e
th e
e n d o g e n o u s g ib b e rillic a c id (GA) c o n c e n tr a tio n to p ro m o te s e e d g e rm in a tio n
(V illiers and W arein g , 1965; E ra n k la n d and W arein g , 1962; C h e n V a rn e r, 1973).
T h e fiv e d ay p r e c h ill t r e a t m e n t , h o w e v e r, w as n o t long eno u g h to o v e rc o m e th e
in h ib ito ry e f f e c t th is ab o v e o p tim u m t e m p e r a tu r e m ay h a v e c a u s e d .
2 5 C ,8 L
tre a tm e n t,
g e rm in a tio n
th e
s ig n ific a n tly
fiv e
over
day
th e
p r e c h ill
c o n tr o l
t r e a tm e n t
in d ic a tin g
in c r e a s e d
th a t
F o r th e
p e rc e n ta g e
g e rm in a tio n
of
b lu e b u n c h w h e a tg ra s s is n o t as s tro n g ly in h ib ite d by th e 2 5 C ,8 L t r e a tm e n t as
w ith th e 3 0 C ,2 4 L t r e a t m e n t . T he p e r c e n ta g e g e rm in a tio n o f t h e n o h -p re c h ille d
t r e a t m e n t a t 2 0 C ,8 L w as g r e a t e r th a n or e q u a l to th e p e r c e n ta g e g e rm in a tio n
o b ta in e d w ith th e 5 o r 10 d a y p r e c h ill t r e a tm e n ts fo r th e o th e r te m p e r a tu r e and
lig h t c o m b in a tio n s .
37
S e e d lo ts v a rie d in t h e ir r e q u ir e m e n t to p re c h illin g w hen g e rm in a te d a t
fiv e t e m p e r a tu r e and lig h t c o m b in a tio n s .
O nly th e 2 0 C ,8 L an d 15-2 5 C ,8 L
t r e a tm e n ts c o n s is te n tly did n o t re q u ire p re c h illin g fo r a ll s e e d lo ts (T able 14).
T h e re w e re o th e r t e m p e r a tu r e
and
lig h t
t r e a tm e n ts
th a t
did n o t re q u ire
p r e c h ill, b u t th e ir re s p o n s e s w e re n o t c o n s is te n t o v e r s e e d lo ts.
T a b le 14. P r e c h ill e f f e c t on t h r e e b lu e b u n c h w h e a tg ra s s s e e d lo t's p e r c e n ta g e
g e rm in a tio n .
S e e d lo ts w e re g e rm in a te d a t fiv e t e m p e r a tu r e and lig h t
c o m b in a tio n s .
P e r c e n ta g e G e rm in a tio n
14 D ay s o f G e rm in a tio n
S e e d lo ts
P r e c h ill
T r e a tm e n ts .
(Days)
T e m p e r a tu r e & L ig h t T r e a tm e n ts
1 5 -2 5 C ,8 L *
20C ,0L
20C ,8L
2 5 C ,8 L 30C ,24L
1980
0
5
10
LSD
30 a
38 a
39 a
10.29
55 b
43 a
65 c
8.27
58 a
58 a
61 a
7.15
38 a
47 b
56 c
5.55
31 a
41 a
54 b
10.51
1981
0
5.
10
LSD
88 a
86 a
89 a
7.34
86 a
87 a
87 a
5.43
92 a
91 a
92 a
4.61
76 a
85 b
86 b
5.29
77 ab
72 a
86 b
11.04
1982
0
5
10
LSD
93 a
96 a
92 a
6.50
91 a
89 a
91 a
5.14
91 a
93 a
93 a
4.32
83 a
88 ab
90 b
5,68
63 a
63 a
7 5 .a
19.81
M ean s in c o lu m n s fo llo w e d b y l e t t e r s in c o m m o n a re n o t s ig n ific a n tly d if f e r e n t
a t th e 5% le v e l o f p ro b a b ility .
* 8L; h o u rs o f lig h t
P r a ir ie S a n d ree d
T h e v ia b ility o f th e 1978, 1980, a n d 1982 s e e d lo ts w as 64% , 88% , and 85% ,
r e s p e c tiv e ly .
S te ff e ru d (1948) r e p o r te d an a v e ra g e o f 75% in g e rm in a tiv e
c a p a c ity fo r p r a ir ie s a n d re e d .
S eed v ia b ility d e c lin e s n o tic e a b ly a s th e se e d is
38
s to r e d b ey o n d fiv e y e a rs .
im p ro p e r s to r a g e
R e p o r ts in d ic a te t h a t re d u c e d v ia b ility is a r e s u lt o f
m e th o d s , u n fa v o ra b le
c o n d itio n s d u rin g d e v e lo p m e n t
and
h a r v e s t, o r n a tu r a l a g e in g (B a rto n , 1961; F lo ris , 1970; J u s tic e a n d B ass, 1978).
S ince th e h is to r y o f th e s e s e e d lo ts is u n know n, w e c a n n o t s p e c u la te f u r th e r on
w h a t c a u se d th e v ia b ility d e c lin e fo r th e 1978 s e e d lo t.
V ario u s te m p e r a tu r e and lig h t c o m b in a tio n s a f f e c t tim e
m ax im u m g e rm in a tio n .
in c r e a s e
fo r
F o r a ll s e e d lo ts , g e rm in a tio n w as c o m p le te in 7 d ay s
w h e n g e rm in a te d a t 2 5 C ,8L and 3 0 C ,24L t r e a tm e n ts (T able 15).
g e rm in a tio n
re q u ire d
b e tw e e n
7 and
14 d a y s
T he la r g e s t
o c c u rre d w ith th e
20C , 8L
tre a tm e n t.
T a b le 15. P e r c e n ta g e g e rm in a tio n o f fiv e te m p e r a tu r e and lig h t c o m b in a tio n s
w ith tim e . P e r c e n ta g e s w e re a v e ra g e d o v e r th r e e p r a ir ie s a n d re e d s e e d lo ts .
P e r c e n ta g e G e rm in a tio n
T e m p e r a tu r e & L ig h t T r e a tm e n ts
L e n g th of
G e rm in a tio n
(Days)
1 5 -2 5 C ,8 L *
20C ,0L
20C ,8L
2 5 C ,8 L
30C ,24L
7
14
21
38
LSD
66 a
74 b
76 b
76 b
2.51
63 a
73 b
74 b
74 b
1.85
52 a
74 b
74 b
75 b
2.63
75 a
78 a
78 a
78 a
3.23
67 a
69 a
69 a
69 a
2.38
M eans in co lu m n s fo llo w e d b y l e t t e r s in c o m m o n a re n o t s ig n if ic a n tly d if f e r e n t
a t th e 5% le v e l o f p ro b a b ility .
* 8L; h o u rs o f lig h t
T he 2 5 C ,8 L t r e a t m e n t w as th e only te m p e r a tu r e and lig h t t r e a tm e n t to
p ro d u c e a p e r c e n ta g e g e rm in a tio n d u rin g th e f ir s t w eek o f g e rm in a tio n th a t w as
e q u a l to v ia b ility o f a ll s e e d lo ts (T able 16),
A f te r 14 d a y s o f g e rm in a tio n ,
s e v e r a l o th e r t e m p e r a tu r e an d lig h t t r e a tm e n ts h a d g e rm in a tio n p e r c e n ta g e s
e q u a l to th e 2 5 C ,8 L t r e a t m e n t , b u t th e r e s u lts w e re n o t c o n s is te n t am ong
39
s e e d lo ts .
H a fe rk a m p an d M cSw ain (1951) r e p o r te d a f lu c tu a tin g 2 0 -3 OC as
o p tim u m .
g e rm in a tio n .
H o w e v er,
th is
te m p e r a tu r e
re q u ir e d
21
days
fo r
c o m p le te
T h e se d a ta s u g g e st t h a t o p tim u m p r o c e d u re fo r s e e d g e rm in a tio n
o f p r a ir ie s a n d re e d is th e 2 5 C ,8 L t r e a tm e n t w ith 7 d ay s o f g e rm in a tio n .
T a b le 16. C o m p a riso n o f p e r c e n t v ia b ility w ith fiv e t e m p e r a tu r e and lig h t
c o m b in a tio n 's p e r c e n ta g e g e rm in a tio n fo r th r e e p r a ir ie s a n d re e d S eed lo ts.
P e r c e n ta g e G e rm in a tio n
L e n g th o f
G e rm in a tio n
(Days)
S e e d lo ts
T e m p e r a tu r e & L ig h t
T r e a tm e n ts
7
1 5 -2 5 C ,8 L *
2 0 C ,0L
2 0 C ,8L
2 5 C ,8L
30 C ,2 4 L
V ia b ility
LSD
14
1 5 -2 5 C ,8 L
2 0 C ,0L
2 0 C ,8 L
2 5 C ,8L
30 C ,2 4 L
V ia b ility
LSD
1978
198.0
1982
53 b
50 b
43 a
62 c
54 b
64 c
5.72 .
79 b
7 9 .b
68 a
85 c
79 b
88 c
4.73
66 c
60 b
44 a
79 d
70 c
85 d
4.29
83 a
85 b
85 b
85b
80 a
. 88 b
3.69
83 b
75 a
77 a
83 b
73 a
85 b
4.51
58 a
58 a
58 a
63 b
55 a
64 b
. 4.21
M eans in co lu m n s fo llo w e d b y l e t t e r s in c o m m o n a re n o t s ig n ific a n tly d if f e r e n t
a t th e 5% IeveL o f p ro b a b ility .
* 8L; h o u rs o f lig h t
S e v e re
g e rm in a tio n .
fu n g a l a c ti v it y
w as o b se rv e d
T he fu n g a l c o n ta m in a tio n
on th e se e d s a f t e r
is a n o th e r re a s o n
14 days o f
w hy 7 days o f
g e rm in a tio n is m o re o p tim u m th a n 14 d a y s. F u n g a l a c tiv ity w ould n o t allow fo r
te tr a z o liu m e v a lu a tio n to d e te c t d o rm a n c y in u n g e rm in a te d s e e d s p r e s e n t a t
t h e end o f th e g e rm in a tio n te s tin g p e rio d (AOSA, 1984).
40
T h e e f f e c t o f an e ig h t h rs. lig h t t r e a tm e n t v e rsu s a c o n tin u o u s d a rk
t r e a tm e n t
on g e rm in a tio n
te m p e r a tu r e
t r e a tm e n t
t e m p e r a tu r e
o f 25C ,
o f p r a ir ie
is u se d .
th e
ra te
s a n d re e d
v a rie s d e p e n d in g
A t th e e s ta b lis h e d o p tim u m
and p e r c e n ta g e
o f se e d
on
w hich
g e rm in a tio n
g e rm in a tio n
a re
e q u iv a le n t fo r b o th lig h t a n d d a rk t r e a tm e n ts (T able 17). H o w e v e r, a t a below
o p tim u m te m p e r a tu r e o f 20C , a slo w e r g e rm in a tio n r a t e o c c u rr e d w ith th e lig h t
tre a tm e n t.
B y 14 d ay s p e r c e n ta g e g e rm in a tio n w as e q u iv a le n t b e tw e e n th e
lig h t and d a rk tr e a tm e n ts .
T a b le 17. C o m p a riso n o f p e r c e n ta g e g e rm in a tio n am ong c o n tin u o u s d a rk and 8
h rs . lig h t t r e a tm e n ts w hen a v e ra g e d o v e r th r e e p r a ir ie s a n d re e d s e e d lo ts . S eeds
w e re g e rm in a te d a t 25C a n d 20C .
P e r c e n ta g e G e rm in a tio n
L ig h t
T r e a tm e n ts
(Hours)
0
8
LSD
25C
20C
7*
14
7
14
72 a
73 a
74 a
74 a
1.86
63 a
52 b
2.37
77 a
77 a
1.94
TM
M eans in co lu m n s fo llo w e d by l e t t e r s in c o m m o n a re n o t s ig n ific a n tly d if f e r e n t
a t th e 5% le v e l o f p ro b a b ility .
.
* D ay s o f g e rm in a tio n
T he p r e c h ill r e q u ir e m e n t fo r p r a ir ie s a n d re e d g e rm in a tio n a p p e a rs to be
d e p e n d e n t upon th e te m p e r a tu r e and lig h t t r e a tm e n t.
O nly th e 25C ,8L and
2 0 C ,0 L t r e a tm e n ts did n o t h a v e in c re a s e d g e rm in a tio n w ith p r e c h ill fo r a ll
s e e d lo ts (T able 18). T he o th e r te m p e r a tu r e and lig h t t r e a tm e n ts h a d a v a ry in g
re s p o n s e am o n g th e s e e d lo ts .
41
T a b le 18.
P r e c h i l l . e f f e c t on th re e p r a ir ie s a n d re e d s e e d lo t's p e r c e n ta g e
g e rm in a tio n .
S e e d lo ts w e re g e rm in a te d a t fiv e t e m p e r a tu r e and lig h t
c o m b in a tio n s fo r 7 d ay s.
P e r c e n ta g e G e rm in a tio n
7 D ay s of G e rm in a tio n
P r e c h ill
T r e a tm e n ts
(Days)
15-2 5 C ,8 L
2 0 C ,0 L
20C ,8L
.0 .
5
10
l Sd
45 a
54 ab
59 b
11.86
54 a
60 a
63 a
28.13
21 a
50 b
62 c
9.92
60 a
70 a
65 a
18.48
58 a
62 ab
66 b
7.34
1980
0
5
10
LSD
70 a
85 b
82 b
8.06
62 a
65 a
71 a
23.48
50 a
64 b
67 b
5.45
67 a
70 a
73 a
20.93
83 a
87 a
86 a
6.73
1982
0
5 ■
10
LSD
63 a
60 a
77 b
9.93
60 a
64 a
68 a
19.73
63 a
60 a
77 b
9.93
62 a
73 a
69 a
23.06 .
S e e d lo ts
, 1978
T e m p e r a tu r e .& L ig h t T r e a tm e n ts
2 5 C ,8 L 30C ,24L
74 a
82 b
81 ab
7.98
M eans in co lu m n s fo llo w e d b y l e t t e r s in c o m m o n a re n o t s ig n ific a n tly d if f e r e n t
a t th e 5% le v e l o f p ro b a b ility .
B asin W ildrye
T h e v ia b ility o f th e 1980, 1981, a n d 1982 s e e d lo ts w as 90% , 94% , and 72% ,
r e s p e c tiv e ly . S f e ff e ru d (1948) r e p o r ts an a v e ra g e
fo r b a sin w ild ry e .
1980 an d 1981
g e rm in a tiv e c a p a c ity o f 83%
T he 1982 s e e d lo t h a s a lo w e r p e r c e n ta g e v ia b ility th a n th e
s e e d lo ts .
T his d e c lin e
m ay b e
a tt r ib u t e d
to
U nfav o rab le
c o n d itio n s d u rin g d e v e lo p m e n t, h a r v e s t, o r s to r a g e t h a t r e s u lte d in f a s t e r se e d
d e te r io r a tio n (B arto n and G a rm a n , 1946; H a rrin g to n , 1972; J u s tic e and B ass,
1978).
T he
1 5 -2 5 C ,8 L , 2 0 C ,0 L , and 2 5 C ,8 L t r e a tm e n ts re q u ir e d 14 d ay s fo r
m ax im u m g e rm in a tio n ; w h e re a s , th e 2 0 C ,8 L a n d 30 C ,2 4 L t r e a t m e n t s re q u ire d
21
days
(T able 19).
T h e 3 0 C ,24L t r e a t m e n t g a v e th e lo w e s t p e r c e n ta g e
'4 2
g e rm in a tio n .
E x te n d in g th e te s tin g p e rio d did n o t im p ro v e g e rm in a tio n a t th is
te m p e r a tu r e and lig h t t r e a tm e n t.
T a b le 19. P e r c e n ta g e g e rm in a tio n o f fiv e te m p e r a tu r e and lig h t c o m b in a tio n s
w ith tim e . P e r c e n ta g e s a re a v e ra g e d o v e r th r e e b a sin w ild ry e s e e d lo ts .________
P e r c e n ta g e G e rm in a tio n
L e n g th o f
G e rm in a tio n
(Days)
1 5 -2 5 C ,8 L *
2 OC5OL
20C ,8L
. ZSC5SXi
30C ,24L
7
14
21
38
LSD
64 a
82 b
.83 b
83 b
3.68
55 a
80 b
80 b
81 b
2.24
62 a
78 b
84 c
85 c
3.29
65 a
84 b
85 b
85 b
3.68
61 a
73 b
75 be
76 c
2.16
T e m p e r a tu r e & L ig h t T r e a tm e n ts
M eans in co lu m n s fo llo w e d by l e t t e r s in c o m m o n a re n o t s ig n ific a n tly d if f e r e n t
a t th e 5% le v e l o f p ro b a b ility .
* 8L; h o u rs o f lig h t
T h e 1 5 -2 5 C ,8 L and 2 5 C ,8 L t r e a t m e n t s c o n s is te n tly p ro v id e d th e h ig h e s t
g e rm in a tio n p e r c e n ta g e s fo r a ll s e e d lo ts , and th e s e p e r c e n ta g e s w e re e q u a l to
s e e d v ia b ility (T able 20). H a rrin g to n (1923), R o lle r (1972) and H e w le y and B lack
(1985) c ite d t h a t h ig h e r te m p e r a tu r e s w ill r e s u lt in m o re ra p id g e rm in a tio n and
g r e a t e r p e r c e n ta g e s .
L ie b e n b u rg (Lang, 1965) w as th e f ir s t to r e p o r t th e
fa v o ra b le e f f e c t s o f d iu rn a l te m p e r a tu r e f lu c tu a tio n .
A s ig n ific a n t in c re a s e in
g e rm in a tio n
se e d s
ra te
and
c a p a c ity
w as
r e p o r te d
in
V aU en tin e (1971) c ite s a lte r n a tin g te m p e r a tu r e s o p tim u m
g e rm in a tio n .
of
m o st
s p e c ie s .
fo r b a s in w ild ry e
T h e se d a ta su g g e st t h a t 2 5 C ,8 L a n d 15 -2 SC ,SL t r e a tm e n ts w e re
o p tim u m fo r g e rm in a tio n o f b a sin w ild ry e .
T he 1 5 -2 5 C ,8 L , 2 0 C j0 L , and 2 5 C ,8 L t r e a tm e n ts show ed no re sp o n se to
p re c h illin g and p e r c e n ta g e g e rm in a tio n w as h ig h fo r a ll t r e a tm e n ts e x c e p t
2 0 C ,0 L
(T able 21).
T he
2 0 C ,8L
and 3 0 C ,2 4 L t r e a t m e n t s . did re sp o n d to
43
p re c h illin g b u t re q u ir e d a t le a s t 14 d ay s o f g e rm in a tio n . T he 30C te m p e r a tu r e
a p p e a rs to b e ab o v e o p tim u m
fo r b a sin w ild ry e g e rm in a tio n
as m axim um
g e rm in a tio n w as n o t r e a c h e d ev e n w ith p re c h ill.
T a b le 20. C o m p a riso n o f p e r c e n t v ia b ility w ith fiv e t e m p e r a tu r e and lig h t
c o m b in a tio n 's p e r c e n ta g e g e rm in a tio n fo r th r e e b a sin w ild ry e s e e d lo ts .
P e r c e n ta g e G e rm in a tio n
14 D ay s o f G e rm in a tio n
S e e d lo ts
T e m p e r a tu r e & L ig h t
T r e a tm e n ts
1980
1981
1982
1 5 -2 5 C ,8 L *
2 0 C ,0 L
2 0 C ,8 L
2 5 C ,8 L
3 0 C ,2 4 L
V ia b ility
LSD
88 c
86 c
81 b
88 c
75 a
90 c
4.01
92 c
87 b
87 b
92 c
81 a
94 c
3.90
67 ab
65 a
65 a
73 b
63 a
72 b
6.50
M eans in co lu m n s fo llo w e d b y l e t t e r s in c o m m o n a re n o t s ig n if ic a n tly d if f e r e n t
a t th e 5% le v e l o f p ro b a b ility .
* 8L; h o u rs o f lig h t
T a b le 2 1 . P r e c h ill e f f e c t on p e r c e n ta g e g e rm in a tio n fo r fiv e te m p e r a tu r e and
lig h t c o m b in a tio n s .
P e r c e n ta g e s w e re a v e ra g e d o v e r t h r e e b a s in w ild ry e
s e e d lo ts .
M ean P e r c e n ta g e G e rm in a tio n
14 D ay s o f G e rm in a tio n
P r e c h ill
T r e a tm e n ts
(Days)
T e m p e r a tu r e & L ig h t T r e a tm e n ts
1 5 -2 5 C ,8 L *
2 0 C ,0L
20C ,8L
2 5 C ,8 L
30C ,24L
0
5
10
LSD
82 a
82 a
84 a
6.28
78 a
78 a
82 a
4.08
70 a
81 b
83 b
6.02
85 a
82 a
85 a
4.2 5
64 a
75 b
79 b
4.10
M ean s in co lu m n s fo llo w e d by l e t t e r s in c o m m o n a re n o t s ig n ific a n tly d if f e r e n t
a t th e 5% le v e l o f p ro b a b ility .
* 8L; h o u rs o f lig h t
44
S p e c ific e v a lu a tio n o f in d iv id u al s e e d lo ts w ith e a c h t e m p e r a tu r e and lig h t
t r e a tm e n t show s no p r e c h ill e f f e c t w ith th e 1 5 -2 5 C ,8 L a n d 2 5 C ,8 L t r e a tm e n ts ,
b u t th e p r e c h ill e f f e c t v a rie d w ith th e o th e r te m p e r a tu r e an d lig h t tr e a tm e n ts
(T able 22). T he a p p lic a tio n o f p r e c h ill to b a s in w ild ry e se e d w hen g e rm in a tin g
a t 1 5 -2 5 C ,8 L o r 2 5 C ,8L t r e a tm e n ts w ill in c r e a s e th e t o t a l te s tin g tim e and n o t
th e p e r c e n ta g e g e rm in a tio n .
T a b le 2 2 . P r e c h ill e f f e c t oil th r e e b a s in w ild ry e s e e d lo t's p e rc e n ta g e
g e rm in a tio n .
S e e d lo ts w e re g e rm in a te d a t fiv e te m p e r a tu r e and lig h t
c o m b in a tio n s fo r 14 d a y s.
P e r c e n ta g e G e rm in a tio n
14 D ay s o f G e rm in a tio n
S e e d lo ts
P r e c h ill
T r e a tm e n ts
(Days)
T e m p e r a tu r e & L ig h t T r e a tm e n ts
----- :------------------- ;---- :-------------------------- --------- 2 0 C ,0L
1 5 -2 5 C ,8 L *
30C ,24L
2 0 C ,8L 2 5 C ,8L
1980
0
5
10
LSD
90 a
88 a
87 a
6.93
85 a
86 a
88 a
8.80
68 a
87 b
89 b
7.31
87 a
87 a
89 a
8.14
57 a
80 b
86 b
7.65
1981
0
5
10
LSD
94 a
88 a
95 a
10.30
84 a
85 a
93 b
6.26
82 a
90 b
91 b
6.53
89 a
89 a
96 a
7.02
78 a
85 a
80 a
7.10
1982
0
5
10
LSD
78 a
70 a
70 a
16.65
65 a
64 a
67 a
8.08
60 a
66 a
69 a
17.33
78 a
72 a
69 a
9.06
58 a
. 60 a
70 b
8.63
M eans in co lu m n s fo llo w e d by l e t t e r s in c o m m o n a re n o t s ig n if ic a n tly d if f e r e n t
a t th e 5% le v e l o f p ro b a b ility .
* 8L; h o u rs o f lig h t
45
P r a ir ie C o n e flo w e r
T he
v ia b ility
r e s p e c tiv e ly .
of
th e
1981
and
1983
s e e d lo ts
w as
89%
and
85% ,
No d e c lin e in v ia b ility p e r c e n ta g e w as e v id e n t w ith s e e d lo t a g e .
S o re n se n an d H old en (1974) an d E d d le m a n (1977) b o th r e p o r te d a h ig h v ia b ility
p e r c e n ta g e o f 99% .
E d d le m a n
g e rm in a tio n .
(1977)
r e p o r ts
p r a ir ie
c o n e flo w e r
re q u ir e s
14
days
of
B ased on o u r s tu d ie s th e d u ra tio n o f g e rm in a tio n fo r p r a ir ie
c o n e flo w e r S eed lo ts v a rie d w ith th e t e m p e r a tu r e and lig h t c o m b in a tio n s (T able
23).
T h re e
te m p e r a tu r e
an d
lig h t
t r e a tm e n ts
r e q u ire d
seven
d ays
of
g e rm in a tio n , w h e re a s tw o te m p e r a tu r e and lig h t t r e a tm e n ts re q u ire d 14 d ay s to
r e a c h m ax im u m g e rm in a tio n .
T a b le 23. P e r c e n ta g e g e rm in a tio n o f tw o p r a ir ie c o n e flo w e r s e e d lo ts w ith tim e
w hen g e rm in a te d a t v a rio u s te m p e r a tu r e an d lig h t c o m b in a tio n s.
P e r c e n ta g e G e rm in a tio n
S e e d lo ts
L e n g th of
T e m p e r a tu r e and L ig h t T r e a tm e n ts
G e rm in a tio n .
30C ,24L
20C ,0L
20C ,8L 2 5 C ,8 L
(Days)
I S-Z SC jSL*
1981
7
14
21
38
LSD
88 a
92 b
92 b
92 b
1.65
. 90 a
91 a
91 a
91 a
1.76
88 a
89 a
89 a
89 a
5.20
88 a
89 a
89 a
89 a
2.33
49 a
55 b
57 b
57 b
3.68
1983
7
14
21
38
LSD
77 a
87 b
90 b
90 b
3.57
59 a
72 b
73 b
73 b
5.13
81 a
89 a
90 a
90 a
9.93
71 a
75 a
76 a
76 a
5.19
11 a
15 a
17 a
19 a
7.03
M eans in .colu m n s follow ed by le tte r s in com m on Eire not s ig n ific a n tly d ifferen t
at th e 5% le v e l o f probability.
* 8L; h o u rs o f lig h t
T h e 2 0 C ,8 L t r e a t m e n t w as th e only te m p e r a tu r e and lig h t t r e a tm e n t t h a t
w as e q u a l to v ia b ility o f b o th s e e d lo ts a t s e v e n d ay s o f g e rm in a tio n (T able 24).
T he 15-^25C,8L t r e a t m e n t w as e q u a l to th e v ia b ility o f th e 1981 s e e d lo t a t
s e v e n d ay s o f g e rm in a tio n and w as e q u a l to th e 1983 s e e d lo t a f t e r 14 d ays o f
g e rm in a tio n .
A lth o u g h th e 2 5 C ,8 L t r e a tm e n t c o m p le te d g e rm in a tio n in se v e n
d a y s, i t d id n o t e q u a l th e v ia b ility o f th e 1983 s e e d lo t. T h e 3 0 C ,2 4 L tr e a tm e n t
w as an in fe r io r t r e a tm e n t fo r g e rm in a tio n o f b o th s e e d lo ts . H o w e v e r, w ith se e d
a g e , th e s e e d lo t's s p e c ific r e q u ir e m e n t to lig h t and te m p e r a tu r e d isa p p e a r so a t
le a s t 50% o f th e s e e d s a re a b le to g e rm in a te a t 3 0 C ,2 4 L .
T a b le 24. C o m p a riso n o f p e r c e n t v ia b ility w ith fiv e te m p e r a tu r e and lig h t
c o m b in a tio n 's p e r c e n ta g e g e rm in a tio n fo r tw o p r a ir ie o o n e flo w e r s e e d lo ts .
P e r c e n ta g e G e rm in a tio n
S e e d lo ts
T e m p e r a tu r e & L ig h t
T r e a tm e n ts
1 5 -2 5 C ,8 L *
2 0 C ,0 L
2 0 C ,8L
2 5 C ,8 L
3 0 C ,2 4 L
V ia b ility
LSD
7 D ays o f G e rm in a tio n
—
'
'
1983
1981
88 b
90 b
88 b
88 b
49 a
89 b
3.18
77 d
. 59 b
81 d
71 c
11 a
85 d
5.13
.
14 D ay s o f G e rm in a tio n
'
i" n
1981
1983
92 b
91 b
89 b
89 b
55 a
89 b
3.18
87 c
72b
89 c
75 b
15 a
85 c
6.37
M eans in co lu m n s fo llo w e d by l e t t e r s in c o m m o n a re n o t s ig n if ic a n tly d if f e r e n t
a t th e 5% le v e l o f p r o b a b ility .
* 8L; h o u rs o f lig h t
T h e se d a ta su g g e st t h a t o p tim u m g e rm in a tio n o f p r a ir ie c o n e flo w e r can
b e a c h ie v e d b y g e rm in a tin g fo r 7 d ays a t 2 0 C ,8 L .
O p tim u m g e rm in a tio n m ay
47
also
b e o b ta in e d w ith th e
1 5 -2 5 C ,8 L t r e a t m e n t , b u t 14 d a y s is re q u ire d .
E d d le m a n (1977) r e p o r te d o p tim u m g e rm in a tio n o f p r a ir ie c o n e flo w e r to o c c u r
a t 20C .
T he
1983
s e e d lo t
e x h ib ite d
a
s ig n if ic a n t
re d u c tio n
in
p e rc e n ta g e
g e rm in a tio n w ith th e d a rk t r e a tm e n t as c o m p a re d to th e 8 h rs. lig h t t r e a tm e n t
a t 2 OC (T able 24). In c re a s in g th e te s tin g d u ra tio n did n o t a l t e r th is e f f e c t . T he
1981 s e e d lo t show ed no e f f e c t due to lig h t o r d a rk tr e a tm e n ts .
S o ren sen and
H o ld en (1974) an d E d d le m a n (1977) r e p o r te d o p tim u m g e rm in a tio n o f p r a ir ie
co n e flo w e r o c c u rre d in a d a rk e n v iro n m e n t, . E v e n a ri (1965) a n d R o lle r (1972)
r e p o r t t h a t w ith an in c r e a s e in se e d a g e m an y s p e c ie 's lig h t re q u ir e m e n ts c a n b e
d im in ish e d or c o m p le te ly e lim in a te d .
B ew ley and B la c k (1985) s t a t e
d a rk
g e rm in a tio n is p h y to c h ro m e c o n tro lle d and th e ir em b ry o c o n ta in s m o re a c tiv e
p h y to c h ro m e th a n lig h t-r e q u ir in g s e e d s . T h e 1983 s e e d lo t's low re sp o n se to th e
2 0 C ,0 L t r e a tm e n t m ay b e a r e s u lt o f a g e rm in a tio n b lo c k w ith in th e se e d t h a t
c a n b e o v e rc o m e w ith th e a d d itio n o f lig h t.
P r e c h illin g fo r 5 a n d 10 d ay s d id n o t im p ro v e g e rm in a tio n o f th e s e e d lo ts
r e g a r d le s s o f th e t e m p e r a tu r e a n d lig h t t r e a tm e n t u se d . F o r so m e te m p e r a tu r e
a n d lig h t tr e a tm e n ts , p r e c h ill lo w e re d th e p e r c e n ta g e g e rm in a tio n o f s e e d lo ts
(T able 25). B ased on th e s e d a ta , i t c a n b e c o n c lu d e d t h a t p re c h illin g o f p r a ir ie
co n e flo w e r w ill n o t in c r e a s e g e rm in a tio n p e rc e n ta g e s ; and if u s e d , could r e s u lt
in lo w e r th a n o p tim u m g e rm in a tio n p e r c e n ta g e s .
48
T a b le 25.
P r e c h ill e f f e c t on tw o p r a ir ie coneflO w er s e e d lo t's p e r c e n ta g e
g e rm in a tio n .
S e e d lo ts w e re g e rm in a te d a t fiv e te m p e r a tu r e and lig h t
c o m b in a tio n s fo r 7 d ay s.
P e r c e n ta g e G e rm in a tio n
7 D ay s o f G e rm in a tio n
P r e c h ill
T r e a tm e n ts
(Days)
1 5 -2 5 C ,8 L *
20C ,0L
1981
0
5
10
LSD
91 a
92 a
93 a
3.38
91 a
91 a
90 a
3.35
89 a
88 a
91 a
10.20
90 a
88 a
89 a
4.63
1983
0
5
10
LSD
87 b
78 a
89 b
6.26
70 a
69 a
63 a
8.90
86 a
84 a
90 a
20.07
66 a
71 ab
9.67
S e e d lo ts
T e m p e r a tu r e and L ig h t T r e a tm e n ts
20C ,8L 2 5 C ,8 L
30C ,24L
63 b
65 b
39 a
6.57
' ^
O
CO
17 a
11 a
17 a
12.33
M eans in co lu m n s fo llo w e d by l e t t e r s in c o m m o n a re n o t s ig n if ic a n tly d if f e r e n t
a t th e 5% le v e l o f p ro b a b ility .
* 8L; h o u rs o f lig h t
A lk ali S a c a to n
S e e d lo t v ia b ility , as d e te rm in e d by T Z , w as 78% fo r th e 19 8 1JK s e e d lo t
and
70%
fo r
th e
198 IN K
s e e d lo t.
P re v io u s
s tu d ie s
(S te ffe ru d ,
1948;
H a f e n r ic h te r e t a l., 1968) h a v e found t h a t a lk a li s a c a to n se e d , fo u r y e a rs old or
le ss, c o n ta in e d a p p ro x im a te ly 80% v ia b le se e d .
K nipe (1969) in d ic a te d t h a t
a lk a li s a c a to n r e m a in s v ia b le u n d e r good s to r a g e fo r o v e r fo u r y e a r s .
u s e d in th is s tu d y w e re fo u r y e a rs old.
S e e d lo ts
V ia b ility o f th e s e s e e d lo ts w e re low er
th a n t h a t e n c o u n te re d w ith H a f e n ric h te r e t a l. (1968) and S te f f e r u d (1948).
G e rm in a tio n o f a lk a li s a c a to n w as ra p id , S eed s in fo u r o f th e te m p e r a tu r e
a n d lig h t t r e a tm e n ts h a d c o m p le te d g e rm in a tio n w ith in se v e n d a y s (T able 26).
O nly
th e
2 0 C ,8 L
t r e a tm e n t
r e q u ire d
14
d ay s
and
i ts
to ta l
g e rm in a tio n
49
p e r c e n ta g e w as th e lo w e s t.
W asser (1982) a lso found c o m p le te g e rm in a tio n to
o c c u r in 5 to 10 d ay s. T o o le (1941) h a d c o m p le te g e rm in a tio n in a m inim um o f
21 d a y s. O u r r e s u lts show ed e x tr e m e s e e d d e c a y due to fungi a f t e r 14 days.
T a b le 26. P e r c e n ta g e g e rm in a tio n o f fiv e te m p e r a tu r e and lig h t c o m b in a tio n s
w ith tim e . P e r c e n ta g e s a re a v e ra g e d o v e r tw o a lk a li s a c a to n s e e d lo ts .
P e r c e n ta g e G e rm in a tio n
T e m p e r a tu r e and L ig h t T r e a tm e n ts
L e n g th o f
G e rm in a tio n
(Days)
1 5 -2 5 C ,8 L *
20C ,0L
20C ,8L
3 0 C ,24L
25C ,8L
7
14
21
28
38
LSD
71 a
74 a
74 a
74 a
74 a
3.49
40 a
42 a
42 a
42 a
42 a
3.35
4a
13 b
14 b
14 b
14 b
2.33
58 a
61 a
61 a
62 a
' 62 3.
6.23
66 a
66 a
66 a
66 a
66 a
4.02
.
M eans in co lu m n s fo llo w e d by l e t t e r s in c o m m o n a re n o t s ig n if ic a n tly d if f e r e n t
a t th e 5% le v e l o f p ro b a b ility .
*8L ; h o u rs o f lig h t
T he 1 5 -2 5 C ,8 L t r e a t m e n t r e s u lte d in m axim um
a lk a li s a c a to n s e e d lo ts (T able 27).
g e rm in a tio n fo r b o th
T he 2 5 C ,8 L t r e a tm e n t also g a v e m ax im u m
g e rm in a tio n fo r th e 1981N K s e e d lo t.
Low p e r c e n ta g e g e rm in a tio n o c c u rre d
w ith b o th lig h t and c o n tin u o u s d a rk t r e a tm e n ts a t 20C , w ith th e lig h t t r e a tm e n t
b e in g s ig n if ic a n tly lo w e r in p e r c e n ta g e g e rm in a tio n th a n th e c o n tin u o u s d a rk
t r e a t m e n t (T able 27).
W ilson (1931) and K n ip e (1967) r e p o r te d s ig n ific a n tly
h ig h e r g e rm in a tio n p e r c e n ta g e s w ith 2(b-30C o r 30-40C te m p e r a t u r e th a n w ith
15-25C t e m p e r a tu r e .
T h e se tw o te m p e r a tu r e s w e re n o t in c lu d e d in th is s tu d y
b e c a u s e th e p e r c e n ta g e s o b ta in e d w ith th e T 5 -2 5 C t r e a tm e n t w e re e q u a l to th e
v ia b ility o f b o th s e e d lo ts .
50
T a b le 27. C o m p a riso n s o f p e r c e n t v ia b ility w ith fiv e t e m p e r a tu r e and lig h t
c o m b in a tio n 's p e r c e n ta g e g e rm in a tio n fo r tw o a lk a li s a c a to n s e e d lo ts .
P e r c e n ta g e G e rm in a tio n
7 D ays o f G e rm in a tio n
S e e d lo ts
T e m p e r a tu r e and L ig h t
T r e a tm e n ts
1981N K
1981JK
1 5 -2 5 C ,8 L *
2 0 C ,0 L
2 0 C ,8 L
2 5 C ,8 L
3 0 C ,2 4 L
V ia b ility
LSD
67 d
28 b
3 a
67 d
56 c
70 d
7 .8 2
75 e
52 b
5 a
66 d
60 c
78 e
5 .2 7
.
M ean s in co lu m n s fo llo w e d b y l e t t e r s in c o m m o n a re n o t s ig n ific a n tly d if f e r e n t
a t th e 5% le v e l o f p ro b a b ility .
* 8L; h o u rs o f lig h t
K nipe (1967) show ed t h a t p e r c e n ta g e g e rm in a tio n w as lo w e r w ith th e 20C
an d 25C te m p e r a tu r e s th a n w ith th e 30C t e m p e r a tu r e .
O ur d a ta fo r th e ZOC
te m p e r a tu r e , w ith b o th lig h t and d a rk c o n d itio n s , a g re e s w ith K n ip e (T able 27).
P e r c e n ta g e
g e rm in a tio n
o f b o th
lig h t
and
d a rk
t r e a tm e n ts
s ig n if ic a n tly lo w e r th a n th e p e r c e n ta g e g e rm in a tio n a t 3 0 C .
at
ZOC
w as
T he 25C ,8L
t r e a t m e n t , h o w e v e r, sh o w ed a s ig n ific a n t in c r e a s e in p e r c e n ta g e g e rm in a tio n a s
c o m p a re d to th e 3 0 C ,2 4 L t r e a t m e n t .
t r e a tm e n t . co u ld
c o n tin u o u s lig h t.
be
a tt r ib u t e d
P e r c e n ta g e
to
T h e lo w e r g e rm in a tio n o f th e 30C ,24L
th e
in h ib ito ry
a c tio n im p o se d
. y
g e rm in a tio n o f a lk a li s a c a to n
by
th e
w as found to
d e c re a s e s ig n if ic a n tly if s e e d s w e re e x p o sed to lig h t fo r 12 h rs . o r lo n g er
(K nipe, 1971).
A t th e b elo w o p tim u m te m p e r a tu r e o f 2 0 C , th e p re s e n c e o f lig h t in h ib its
b o th r a t e (T able 26) and p e r c e n t g e rm in a tio n (T able 28).
T h e low c o n s ta n t
t e m p e r a tu r e , p lu s th e p r e s e n c e o f lig h t, m ay b e th e re a s o n fo r low p e r c e n ta g e
51
g e rm in a tio n .
A p p a re n tly ,
8 h rs.
lig h t
t r e a tm e n t
is m o re
g e rm in a tio n o f a lk a li s a c a to n a t 2 0 C th a n a t 15-25C .
in h ib ito ry on
T h e 19 8 1JK s e e d lo t
e x h ib ite d a g r e a t e r g e rm in a tio n c a p a c ity th a n did th e 1981N K s e e d lo t.
T a b le 28. C o m p a riso n o f p e r c e n ta g e g e rm in a tio n am ong c o n tin u o u s d a rk an d 8
h rs . lig h t t r e a tm e n ts fo r tw o a lk a li s a c a to n s e e d lo ts ; S eeds w e re g e rm in a te d a t
15 -2 5 C a n d 20C fo r 7 d ay s.
P e r c e n ta g e G e rm in a tio n
7 D ay s o f G e rm in a tio n
15-25C
20C
L ig h t T r e a tm e n ts
1981N K
1981JK
1981N K
1981JK
0 h rs
66 a
77 a
28 b
52 b
8 h rs
65 a
74 a
3 a
5 a
2.83
4.06
7.82
5.27
LSD
M eans in co lu m n s fo llo w e d by l e t t e r s in c o m m o n a re n o t s ig n ific a n tly d if f e r e n t
a t th e 5% le v e l o f p ro b a b ility .
C o m p a riso n s w e re m ad e b e tw e e n s e e d s g e rm in a te d in 8 h rs .
c o n tin u o u s d a rk fo r 7 d a y s a t 15-25C (T able 28).
te m p e r a tu r e
of
15 -2 5 C
sh o w ed
no
o f lig h t and
G e rm in a tio n a t th e o p tim u m
s ig n ific a n t
g e rm in a tio n b e tw e e n th e lig h t and d a rk c o n d itio n s .
d if f e r e n c e
in
p e r c e n ta g e
S eeds t h a t h a d g e rm in a te d
in th e d a rk g e rm in a te d f a s t e r b e c a u s e th e le n g th o f th e e p ic o ty ls fro m th e d a rk
t r e a tm e n t w e re a p p ro x im a te ly 3.75 cm as c o m p a re d to 1.75 cm le n g th fo r th e
lig h t t r e a tm e n t.
P r e c h ill did n o t in c r e a s e a lk a li s a c a to n p e r c e n ta g e g e rm in a tio n e x c e p t fo r
th e
2 0 C ,0 L
t r e a tm e n t
(T able
g e rm in a tio n o f th is t r e a tm e n t
29).
F iv e
d ay s
of
p r e c h ill
enhanced
th e
fo r b o th s e e d lo ts , b u t te n d a y s o f p re c h ill
s ig n if ic a n tly re d u c e d th e g e rm in a tio n o f th e 1981N K s e e d lo t.
in c r e a s e g e rm in a tio n o f th e 2 0 C ,8 L t r e a t m e n t .
P r e c h ill did n o t
T his m ay b e d u e to a s tro n g
52
in h ib ito ry e f f e c t w ith lig h t on a lk a li s a c a to n g e rm in a tio n .
s a c a to n se e d is u n c o m m o n
D o rm a n c y in a lk a li
(W ilson, 1931; T o o le , . 1941; W asser,
1982)
and
g e rm in a tio n is n o rm a lly ra p id ; t h e r e f o r e , p r e c h ill w ould n o t b e e x p e c te d to
im p ro v e g e rm in a tio n .
T a b le 29.
P r e c h ill e f f e c t on tw o a lk a li s a c a to n s e e d lo t's p e rc e n ta g e
g e rm in a tio n .
S e e d lo ts w e re g e rm in a te d a t fiv e t e m p e r a tu r e and lig h t
c o m b in a tio n s fo r 7 d a y s.
P e r c e n t G e rm in a tio n
7 D ay s o f G e rm in a tio n
S e e d lo ts
P r e c h ill
T r e a tm e n ts
(Days)
T e m p e r a tu r e and L ig h t T r e a tm e n ts
~
'
'
"
~
'
2 0 C ,8 L 3 0 C ,2 4 L
1 5 -2 5 C ,8 L *
2 0 C ,0 L
25C ,8L
198 IN K
O
5
10
LSD
68 a
69 a
65 a
11.45
29 b
41 c
14 a
9.70
I a
4 a
6 a
5,64
57 a
49 a
63 a
28.24
63 a
70 a
67 a
7.81
1981JK
0
5
10
LSD
79 b
65 a
80 b
10.06
45 a
57 b
52 ab
7.31
4 a
4 a
6 a
8.15
53 a
66 a
62 a
21.10
62 a
71 a
65 a
13.64
M eans in co lu m n s fo llo w e d by l e t t e r s in c o m m o n a re n o t s ig n if ic a n tly d if f e r e n t
a t th e 5% le v e l o f p ro b a b ility .
* 8L; h o u rs o f lig h t
S u m m a ry
R a r e ly do se e d te s tin g la b o r a to r ie s know th e ag e and e n v iro n m e n ta l
c o n d itio n s o f a s e e d lo t.
W hen g e rm in a tin g se e d s it is im p o r ta n t t h a t th e
p ro c e d u re u se d d o es n o t d is c rim in a te
b e tw e e n s e e d o f th e sa m e s p e c ie s .
am o n g th e d iv e r s ity t h a t c a n o c c u r
W hen ch o o sin g th e o p tim u m g e rm in a tio n
p ro c e d u re fo r a s p e c ie s , th e s e d iv e r s itie s n e e d to b e c o n s id e re d .
M axim um
g e rm in a tio n n e e d s to b e a tt a in e d in th e s h o r te s t p o ssib le tim e . N o u n n e c e s s a ry
s te p s
sh o u ld
be
u se d
w h ich
w ould
in c r e a s e
th e
tim e
in
p r e p a r a tio n
or
53
g e rm in a tio n .
T he m o st im p o r ta n t c o n s id e ra tio n is t h a t th e s a m p le s v ia b ility
m u st b e e x p re s s e d in th e p e r c e n ta g e g e rm in a tio n .
T h e p r o c e d u re s t h a t m e e t
th e s e c r i t e r i a fo r th e six n a tiv e ra n g e s p e c ie s a re s u m m a riz e d .
Y a rro w .
O p tim u m
g e rm in a tio n
o f y a rro w
o c c u re d w hen se e d s w e re
g e rm in a te d fo r 14 d ay s a t 2 OC w ith 8 h rs. o f lig h t. V ia b ility , a s d e te r m in e d by
T Z 5 and th e p e r c e n ta g e g e rm in a tio n w e re e q u a l for b o th s e e d lo ts .
N e ith e r
s e e d lo t re q u ire d p re c h illin g to a tt a in m ax im u m g e rm in a tio n .
B lu eb u n ch W h e a tg ra s s .
O p tim u m g e rm in a tio n o f b lu e b u h c h w h e a tg ra s s
s e e d lo ts w as o b ta in e d by g e rm in a tin g a t 20C w ith 8 h rs. o f lig h t.
P re c h illin g
w as u n n e c e s s a ry and if a p p lie d w ould in c r e a s e th e d u ra tio n o f th e t e s t p e rio d .
B lu eb u n ch w h e a tg ra s s se e d should be g e rm in a te d fo r 14 d a y s.
U n g e rm in a te d
s e e d s should b e
th e
checked
fo r
d o rm a n c y
w ith
TZ.
E xposing
se e d s to
g e rm in a tio n fo r lo n g er th a n 14 d ay s r e s u lte d in in c re a s e d fu n g i a c tiv ity and
e v e n tu a l d e a th o f v ia b le s e e d s .
P e r c e n ta g e
v ia b ility o f a ll s e e d lo ts w as
o b ta in e d w ith th is g e rm in a tio n p ro c e d u re .
P r a ir ie
S a h d re e d .
O p tim u m
g e rm in a tio n
fo r th r e e
p r a ir ie
sa n d re e d
s e e d lo ts w as a tta in e d by g e rm in a tin g a t 25C fo r 7 d ay s in 8 h rs. lig h t or
c o n tin u o u s
d a rk
c o n d itio n s .
P re c h illin g ,
p rio r
to
g e rm in a tio n ,
w as n o t
n e c e s s a ry . P e r c e n ta g e g e rm in a tio n by th is p ro c e d u re w as e q u a l to TZ v ia b ility
p e r c e n ta g e s .
B a sin
W ild ry e.
B asin w ild ry e
w ill g e rm in a te o v e r a w ide ra n g e o f
te m p e r a tu r e and lig h t c o m b in a tio n s . Som e o f th e s e t r e a tm e n ts p ro v id e f a s te r
g e rm in a tio n
th a n
o th e r s .
T he
m o st
ra p id
p ro c e d u re
g e rm in a tio n w as th e 1 5 -2 5 C ,8 L and th e 2 5 C ,8 L t r e a tm e n ts .
fo r
d e te rm in in g
S eed s n e e d to b e
54
g e rm in a te d
fo r
te m p e r a tu r e s .
v ia b ility .
14 d a y s.
P re c h ill did n o t
im p ro v e
g e rm in a tio n a t th e s e
P e r c e n ta g e g e rm in a tio n o f s e e d lo ts w as e q u a l to p e rc e n ta g e
A TZ t e s t m ay b e c o n d u c te d to d e t e c t p o ssib le d o rm a n c y i f firm
u n g e rm in a te d se e d s re m a in a t th e end o f th e te s tin g p e rio d .
P r a ir ie
C o n e flo w e r.
R a p id and m ax im u m
g e rm in a tio n occU red w hen
p r a ir ie c o n e flo w e r se e d s w e re g e rm in a te d fo r se v e n d ays a t 2 0 0 w ith 8 h rs. o f
lig h t.
M axim um g e rm in a tio n w as also a tta in e d w ith th e 1 5 -2 5 C ,8 L tre a tm e n t^
b u t 14 d ay s o f g e rm in a tio n w as re q u ire d .
B o th o f th e s e t e m p e r a tu r e and lig h t
t r e a t m e n t s p ro v id e g e rm in a tio n p e r c e n ta g e s e q u a l to th e p e r c e n ta g e v ia b ility
o f th e s e e d lo ts . P re c h illin g a p p e a re d to s tr e s s th e se e d s w h ich r e s u lte d in lo w er
p e r c e n ta g e g e rm in a tio n .
A lk a li S a c a to n .
M axim um g e rm in a tio n o f a lk a li s a c a to n w a s o b ta in e d
w h en Seeds w e re g e rm in a te d fo r s e v e n d ay s a t 15-25C w ith 8 h rs . o f lig h t or in
c o n tin u o u s d a rk .
P re c h illirig is n o t n e c e s s a ry a t th is te r n p e r a tu r e to o b ta in
o p tim a l g e rm in a tio n .
a lk a li s a c a to n s e e d lo ts .
T h is p ro c e d u re r e f l e c t s th e m axim um v ia b ility o f th e
55
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