The effects of misting upon seed yield of birdsfoot trefoil, Lotus corniculatus L., and the relationship of
moisture content of pod, seed and fruit at dehiscence
by Mark Andrew Hughes
A thesis submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE
in Agronomy
Montana State University
© Copyright by Mark Andrew Hughes (1982)
Abstract:
Seed pod dehiscence is the major factor limiting birdsfoot trefoil seed production. Birdsfoot trefoil has
an indeterminate growth habit resulting in all stages of pod maturation occurring on the same plant at
the same time. As a result many mature pods dehisce before being harvested. Research has shown that
although 784-1008 kg/ha of seed is possible, only 155-224 kg/ha can usually be harvested with
conventional harvest methods because of seed pod dehiscence.
Investigations into increasing seed yields of birdsfoot trefoil through use of an irrigation management
program (misting) were conducted at the Field Research Laboratory, Bozeman, MT in 1979 and 1980.
Misting treatments were: 1) no misting, 2) twice daily misting, and 3) hourly misting. Seed yields were
obtained on four harvest dates in both years. In addition, laboratory experiments were conducted to
determine the moisture percentage of pods at dehiscence, and evaluate the variation of moisture at
dehiscence of four clones of birdsfoot trefoil.
Pod dehiscence occurred at approximately 10% moisture. In 1979, misting delayed pod dehiscence and
allowed immature pods to mature prior to harvesting for seed. Maximum seed yield and seed viability
were obtained with twice daily misting and harvesting when approximately 70% of all pods were
brown. Hourly misting decreased pod dehiscence and increased yield, but resulted in lower seed
viability due to moldy seed and seed pods, and seeds germinating in the pod.
In 1980, cool, wet conditions were encountered during seed pod maturation. These conditions delayed
pod maturation. Misting was not necessary, and when used (for purposes of this experiment) decreased
seed yield.
These data suggest that in dry areas of the western United States, it may be possible to prevent pod
dehiscence through periodic misting of the birdsfoot trefoil canopy with sprinkler irrigation. STATEMENT OF PERMISSION TO COPY
In p re s e n tin g t h i s t h e s is in p a r t i a l f u l f i l l m e n t o f th e r e q u ir e ­
ments f o r an advanced degree a t Montana S ta te U n iv e r s it y , I agree t h a t
th e L ib r a r y s h a ll make i t f r e e l y a v a ila b le f o r in s p e c tio n .
I fu rth e r
agree t h a t p e rm is s io n f o r e x te n s iv e co p y in g o f t h i s t h e s is f o r s c h o la r ly
purposes may be g ra n te d by my m a jo r p r o fe s s o r , o r , in h is absence, by th e D ir e c to r o f L ib r a r ie s .
I t is und e rsto o d t h a t any co p yin g o r p u b lic a tio n
o f t h i s t h e s is f o r f in a n c ia l g a in s h a ll n o t be a llo w e d w ith o u t my
w r it t e n p e rm is s io n .
S ig n a tu re
Date
Ia —
ij>
7
c,
THE EFFECTS OF MISTING UPON SEED YIELD OF BIRDSFOOT TREFOIL,
LOTUS CORNICULATUS L . , AND THE RELATIONSHIP OF MOISTURE
CONTENT OF POD, SEED AND FRUIT AT DEHISCENCE
by
.
MARK ANDREW HUGHES
A t h e s is s u b m itte d in p a r t i a l f u l f i l l m e n t
o f th e re q u ire m e n ts f o r th e degree
of
MASTER OF SCIENCE
in
Agronomy
A pproved:
C hairm an, G raduate Committee
G raduate Dean
MONTANA STATE UNIVERSITY
Bozeman, Montana
A ugust. 1982
iii
ACKNOWLEDGMENTS
I w ish t o exp re ss my deepest a p p re c ia tio n t o D r. Loren E. W iesner
f o r h is guidan ce and s u p p o rt as my m a jo r p ro fe s s o r and f r i e n d .
I would
a ls o l i k e t o exp re ss my g r a t it u d e t o D r. C. S. Cooper and D r. Ray
D i t t e r l i n e f o r t h e i r encouragement and a s s is ta n c e w ith th e c o m p le tio n
o f my g ra d u a te program .
For h is h e lp and a d v ic e w ith th e p re p a ra tio n
o f t h i s t h e s is , I would a ls o l i k e t o th a n k D r. Ronald Lockerm an.
I a ls o th a n k my w if e , K a th y , f o r h e r s u p p o rt and p a tie n c e d u rin g
th e y e a rs t h a t I was a .g ra d u a te s tu d e n t and f o r h e lp in g t o make t h i s
a l l p o s s ib le .
TABLE OF CONTENTS
Page
VITA . . . .
...
. ............................... ............................................... ....
ACKNOWLEDGMENTS . ...................... .................................. ............................... .... .
LIST OF TABLES . . .....................................................
LIST OF FIGURES
ABSTRACT
.................. ............................................................ ....
.................. ....
LITERATURE REVIEW
. . . . . .
..................
H i
v
vi
v ii
. ............................................
I
\ CM CO
M o rp h o lo g ic a l C h a r a c te r is tic s
.........................................................
C u ltu r a l P ra c tic e s . ...................... ............................................... .... . '
Improvement o f Seed Y ie ld and P re v e n tio n
o f Pod Dehiscence
................................................
CHAPTER I :
ii
6
THE EFFECTS OF MISTING ON PHYSIOLOGICAL
DEVELOPMENT, POD DEHISCENCE, AND SEED
YIELD OF BIRDSFOOT TREFOIL (LOTUS
CORNICULATUS L . ) ...................... ™ T T ........................................
12
I n t r o d u c t i o n ...................... . . . . . . . . .
........................... .
M a te r ia ls and M e t h o d s .................................................................
R e s u lts and D is c u s s io n ...................................................
12
13
16
CHAPTER I I :
THE RELATIONSHIP OF MOISTURE PERCENTAGE
OF POD, SEED, AND FRUIT AT DEHISCENCE
OF BIRDSFOOT TRETOIL ( LOTUS CORNICULATUS L . ) . . . .
I n tr o d u c tio n ..........................
M a te r ia ls and M e t h o d s .................................................................. .... .
R e s u lts and D is c u s s io n ..........................................................................
LITERATURE C IT E D .........................................................
31
31
32
34
38
-
V
n
LIST OF TABLES
T ab le
1.
2.
3.
4.
5.
6.
Page
W eather summary f o r 1979-80 a t Bozeman, MT ...............................
17
The e f f e c t s o f th re e m is tin g tre a tm e n ts
upon seed, y ie ld components o f b i.r d s fo o t
. t r e f o i l a t Bozeman, MT, 1979 .............................................. ....
18
The e f f e c t s o f f o u r h a rv e s t d a te s upon
seed y ie ld components o f b ir d s f o o t t r e f o i l
a t Bozeman, MT, 1979 ................................... .................................. .... . .,
19
The e f f e c t s o f th r e e m is tin g tre a tm e n ts
upon t o t a l seed w e ig h t p e r 100 seed a t
f o u r h a rv e s t d a te s o f b ir d s f o o t t r e f o i l
a t Bozeman, MT, 1979 ...................... .................................. ....
25
The e f f e c t s o f th r e e m is tin g tre a tm e n ts
upon p e rc e n t v i a b i l i t y o f seed lo t s o f
b ir d s f o o t t r e f o i l a t Bozeman, MT, 1979 ...................... ....
28
t h e e f f e c t s o f f o u r h a rv e s t d a te s on p e r­
c e n t v i a b i l i t y o f seed lo t s o f b ir d s f o o t
t r e f o i l a t Bozeman, MT, 1979 ...............................
28
7.
M o is tu re p e rce n ta g e o f f r u i t fro m f o u r
c lo n e s o f b ir d s f o o t t r e f o i l a t dehiscen ce
in 1980 a t Bozeman, MT . '............................................ ..............................35
8.
M o is tu re p e rce n ta g e o f f r e s t f r u i t o f fo ur,
c lo n e s o f b ir d s f o o t t r e f o i l when p la c e d in
an e n v iro n m e n ta l chamber a t Bozeman, M T ........................................
9.
10.
C o r r e la tio n m a tr ix showing th e r e la t io n s h ip
o f m o is tu re p e rce n ta g e o f pod, seed , and
f r u i t a t d e h is c e n c e ............................................................................... .
Means, s ta n d a rd d e v ia t io n s , and s ta n d a rd
e r r o r s o f th e p e rc e n t m o is tu re o f pod s,
seeds, and f r u i t a t dehiscen ce ................................... ....
35
37
37
LIST OF FIGURES
F ig u re
1.
2.
3.
4.
5.
Page
The e f f e c t s o f th r e e m is tin g tre a tm e n ts
and f o u r h a rv e s t d a te s upon p e rc e n t brown
pods o f b ir d s f o o t t r e f o i l a t Bozeman, MT 1979 . . . . . . .
21
The e f f e c t s o f th re e m is tin g tre a tm e n ts
and f o u r h a rv e s t d a te s upon p e rc e n t
s h a tte re d pods o f b ir d s f o o t t r e f o i l a t
Bozeman, MT, 1979 ............................................................................... .... .
23
The e f f e c t s o f th r e e m is tin g tre a tm e n ts
and f o u r h a rv e s t d a te s upon p e rc e n t pod
m o is tu re o f b ir d s f o o t t r e f o i l a t Bozeman, MT, 1979
24
. . . .
The e f f e c t s o f th re e m is tin g tre a tm e n ts
and f o u r h a rv e s t da te s upon seed y ie ld
o f b ir d s f o o t t r e f o i l a t Bozeman, MT, 1979 ...................................
26
The e f f e c t s o f th r e e m is tin g tre a tm e n ts
and f o u r h a rv e s t d a te s upon seed y ie ld
o f b ir d s f o o t t r e f o i l a t Bozeman, MT, 1980 . ...............................
29
ABSTRACT
Seed pod d eh iscen ce is th e m a jo r f a c t o r l i m i t i n g b ir d s f o o t t r e f o i l
seed p r o d u c tio n . B ir d s fo o t t r e f o i l has an in d e te rm in a te grow th h a b it
r e s u lt in g in a l l stages o f pod m a tu ra tio n o c c u r r in g on th e same p la n t
a t th e same tim e . As a r e s u lt many m ature pods d e h isce b e fo re being
h a rv e s te d . Research has shown t h a t a lth o u g h 784-1008 k g /h a o f seed
is p o s s ib le , o n ly 155-224 kg /h a can u s u a lly be h a rve ste d w ith conven­
t io n a l h a rv e s t methods because o f seed pod d e h isce n ce .
I n v e s tig a tio n s in t o in c re a s in g seed y ie ld s o f b ir d s f o o t t r e f o i l
th ro u g h use o f an i r r i g a t i o n management program ( m is tin g ) were conducted
a t th e F ie ld Research L a b o r a to ry , Bozeman, MT in 1979 and 1980. M is tin g
tre a tm e n ts w e re: I ) no m is t in g , 2) tw ic e d a i ly m is t in g , and 3) h o u rly
m is t in g . Seed y ie ld s w e re .o b ta in e d on f o u r h a rv e s t d a te s in both y e a rs .
In a d d it io n , la b o r a to r y e xp e rim e n ts were conducted t o d e te rm in e th e
m o is tu re p e rce n ta g e o f pods a t d e h is c e n c e , and e v a lu a te th e v a r ia t io n
o f m o is tu re a t d eh iscen ce o f f o u r c lo n e s o f b ir d s f o o t t r e f o i l .
Pod deh isce n ce o c c u rre d a t a p p ro x im a te ly 10% m o is tu r e .
In 1979,
m is tin g dela ye d pod d eh iscen ce and a llo w e d immature pods t o m ature
p r i o r t o h a r v e s tin g f o r seed. Maximum seed y ie ld and seed v i a b i l i t y
were o b ta in e d w ith tw ic e d a i ly m is tin g and h a rv e s tin g when a p p ro x im a te ly
70% o f a l l pods were brow n. H o u rly m is tin g decreased pod dehiscence and
in c re a s e d y ie ld ., b u t r e s u lte d in lo w e r seed v i a b i l i t y due t o m oldy seed
and seed pods, and seeds g e rm in a tin g in th e pod.
In 1980, c o o l, w et c o n d itio n s were encountered d u r in g seed pod
m a tu ra tio n . These c o n d itio n s delayed pod m a tu ra tio n . M is tin g was n o t
n e c e s s a ry , and when used ( f o r purposes o f t h i s e x p e rim e n t) decreased
seed y i e l d .
These d a ta suggest t h a t in d ry areas o f th e w e ste rn U n ite d S ta te s ,
i t may be p o s s ib le t o p re v e n t pod d e h isce n ce th ro u g h p e r io d ic m is tin g
o f th e b ir d s f o o t t r e f o i l canopy w ith s p r in k le r i r r i g a t i o n .
LITERATURE REVIEW
B ir d s fo o t t r e f o i l
B r it is h
(L o tu s c o r n ic u la tu s L . ) , is n a tiv e t o th e
I s le s and th e re g io n from th e M e d ite rra n e a n Sea n o rth w a rd to
th e S ca ndinavia n
P e n in s u la (1 5 , 24, 3 7 ).
McKee and Schoth (24)
re p o rte d t h a t i t was in d ig e n o u s t o Europe, exce p t in Lapland and
N o rth e rn R u ssia , and is
They re p o rte d i t s
its
la r g e ly an a lp in e p la n t in S outhern Europe.
o ccu rre n ce a ls o in A f r ic a , A s ia , and A u s t r a lia and
absence in A m erica.
MacDonald (2 1 ) re p o rte d t h a t th e sp e cie s is
n o t n a tiv e o f th e Western Hem isphere, b u t was in tro d u c e d from Europe
as an im p u r ity in im p o rte d seed.
B ir d s fo o t t r e f o i l , is a lo n g - liv e d p e r e n n ia l, n o n - b lo a tin g , and
g e n e r a lly nondemanding in i t s m o is tu re , f e r t i l i t y
ments (1 2 , 3 7 ).
It
and g ra z in g r e q u ir e ­
is an im p o rta n t fo ra g e cro p in c e r t a in areas o f th e
U n ite d S ta te s s u ita b le f o r grow ing a l f a l f a , red c lo v e r , o r w h ite c lo v e r
(2 1 , 3 0 ) .
its
No o th e r ir r ig a t e d p a s tu re legume e qu als b ir d s f o o t t r e f o i l
in
d u r a tio n and a b i l i t y t o w ith s ta n d c o n tin u o u s g ra z in g ( 4 0 ) .
F a c to rs l i m i t i n g th e s u c c e s s fu l use o f t h i s crop a re r e l a t i v e l y
low fo ra g e y ie ld s
( 4 3 ) , sm a ll seed s iz e (10, 1 1 ), la c k o f s e e d lin g v ig o r
(1 3 , 4 3 ) , seed pod dehiscen ce (3 , 22, 25, 3 2 ), h ig h seed c o s t and
in a deq uate s u p p lie s o f seed (3 , 21, 23, 25, 32, 3 6 ).
2
M o rp h o lo g ic a l C h a r a c te r is tic s
. B ir d s fo o t t r e f o i l has 20-70 o v u le s p e r o v a r y , a v e ra g in g about 45.
U s u a lly , o n ly an average o f about 20 o v u le s p e r o v a ry d e ve lo p in t o
m ature seed ( 8 , 3 6 ) .
Budar (8 ) found t h a t o vu le s w it h in an in d iv id u a l
o v a ry v a ry c o n s id e ra b ly in r a te o f develop m en t.
Because o f t h i s ,
o v a rie s c o n ta in some f e r t i l i z a b l e o v u le s f o r 8-10 d a y s , a lth o u g h i n d i ­
v id u a l o v u le s a re f e r t i l i z a b l e f o r o n ly 2 o r 3 days ( 3 6 ) .
A f t e r p o l l i n a t i o n , pods deve lop r a p id ly re a c h in g maximum le n g th in
abo ut 3 weeks.
The c o lo r o f th e pods changes from d a rk green o r p u rp le
t o l i g h t g re e n , t a n , l i g h t brown and f i n a l l y t o brown o r b la c k .
Seeds
become p h y i s io lo g i c a l ly m ature s l i g h t l y b e fo re o r a t th e tim e pods tu r n
l i g h t brown ( 3 , . 2 3 , 3 6 ) .
W iggans, e t a l . (4 6 ) noted t h a t seeds m ature
7-10 days b e fo re pod d e h is c e n c e .
by w e a th e r c o n d it io n s .
Rate o f pod developm ent is in flu e n c e d
S. R. Anderson ( 3 ) , w o rkin g in Iow a, found t h a t
m ature pods and seeds form ed 24-47 days a f t e r p o l l i n a t i o n , w h ile in New
Y o rk i Winch (4 7 ) found t h a t th e same sta g e o f developm ent re q u ire d
26-38 d a y s .
v
Seed s e t in b ir d s f o o t t r e f o i l depends bn p o l li n a t io n o f flo w e rs by
in s e c ts .
T h is is accom plished p r im a r ily by v a rio u s s p e c ie s o f p o lle n
and n e c ta r c o lle c t in g honey bees (H ym enoptera) , w hich a re capable o f
t r i p p in g th e flo w e rs ( 5 ) .
Morse (2 7 ) found t h a t honey bee p o p u la tio n s
o f one bee p e r 0 .9 square m eter o r 2 .5 c o lo n ie s ( h iv e s ) p e r h e c ta re are
n e e d e d .fo r maximum seed p r o d u c tio n .
3
C u ltu r a l P ra c tic e s
The p r o s t r a t e grow th h a b it o f b ir d s f o o t t r e f o i l reduces seed y ie ld s
(2 1 ).
Anderson and M e tc a lfe (4 ) noted reduced lo d g in g and in crea sed
seed y ie ld s when b ir d s f o o t t r e f o i l was grown w ith Kentucky b lu e g ra s s ,
o rc h a rd g ra s s , o r tim o th y .
H ig h e s t seed y ie ld s were o b ta in e d in th e
b ir d s f o o t t r e f o i !-K e n tu c k y b lu e g ra s s m ix tu r e .
In c o n tr a s t o th e r r e ­
se a rch e rs (2 3 , 36) have in d ic a te d t h a t p u re stands o f b ir d s f o o t t r e f o i l
produce th e h ig h e s t seed y ie ld s .
■
i
They in d ic a te t h a t as th e amount o f
1
g ra ss in c re a s e d , th e seed y ie ld d e c lin e d .
C lip p in g in th e s p rin g d e la y s f lo w e r in g and seed s e t , and extends
th e p e rio d o f seed h a rv e s t ( 3 6 ) .
D e la y in g seed h a rv e s tin g may reduce
seed pod d eh iscen ce by c o in c id in g w ith c o o le r w eather o r h ig h e r h u m id ity
e n v iro n m e n ts .
Winch (4 7 ) re p o rte d t h a t c lip p in g b ir d s f o o t t r e f o i l a t
e a r ly bud sta g e delayed seed h a rv e s t seven d a ys.
O ther s tu d ie s ( 4 , 5)
in d ic a te d t h a t s p rin g and e a r ly summer c lip p in g reduces seed y ie ld s in
com parison t o u n c lip p e d s ta n d s .
A l l c u l t i v a r s o f Lotus c o r n ic u la tu s L. flo w e r and s e t seed o v e r an
extended p e rio d o f tim e ; u s u a lly f o u r t o s ix weeks (2 1 , 3 6 , 3 7 ).
I n d i­
v id u a l p la n ts w i l l have flo w e r s , r ip e po d s, and some d e h isce d pods (3 ,
2 3 , 24, 29, 3 2 , 4 7 ) .
T h is in d e te rm in a te flo w e r in g and seed s e t makes,
h a rv e s t t im in g c r i t i c a l f o r maximum seed y i e l d .
H a rv e s tin g to o e a r ly
I
'
reduces y ie ld and r e s u lt s in im m ature and n o n v ia b le seed.
H a rv e s tin g
to o la t e reduces y ie ld due t o pod d e h isce n ce (3 , 32, 36, 4 0 ).
4
S e ve ra l methods have been used t o h a rv e s t seed ( 2 3 ) .
The most
common method used in th e N o rth e a s t is t o mow o r w in d ro w , and then com­
b in e .
The w indrow is a lld w e d t o d ry b e fo re c o m b in in g .
T h is method can
r e s u lt in e x c e s s iv e seed lo sse s d u rin g th e d ry down p e rio d o f th e f o r ­
age.
D ir e c t com bin ing o f b ir d s f o o t t r e f o i l has been used b u t , in
g e n e r a l, is n o t a c c e p ta b le .
Large q u a n t it ie s o f green fo ra g e go th ro u g h
th e com bine, w hich slow s h a rv e s t and causes seed lo s s by c lo g g in g o f th e
h a rv e s te r ( 4 0 ) .
Chemical d e s ic c a n ts and d e f o lia n t s s u c c e s s fu lly de­
f o l i a t e and d ry th e p la n ts b e fo re h a rv e s t w hich a id s in d i r e c t co m b in in g .
Jones (1 8 ) re p o rte d t h a t U n iv e r s it y o f C a lif o r n ia s c ie n t is t s found t h a t
d i n i t r o h e r b ic id e s a id e d in h a rv e s tin g o f b ir d s f o o t t r e f o i l seed.
He
s t a te s :
. . .when d i n i t r o compounds are p r o p e r ly used as a d e f o l ia n t ,
b ir d s f o o t t r e f o i l can be combined w ith o u t s ig n if ic a n t lo s s o f
seed th ro u g h s h a t t e r in g . 1P roper i r r i g a t i o n p r a c tic e s w i l l
e lim in a te much o f th e seed lo s s t h a t u s u a lly occu rs p r i o r to
h a r v e s t.
Cooper (1 4 ) was f i r s t t o r e p o r t th e use o f sodium cyanamid as a d e te r ­
r e n t t o pod s h a t t e r in g .
He concluded t h a t 27 kg /h a o f sodium cyanamid
a p p lie d j u s t p r i o r t o h a rv e s t r e s u lte d in com plete f o lia g e k i l l o f
b ir d s f o o t t r e f o i l and d e la ye d pod d e h is c e n c e .
However, s p ra y in g to o
e a r ly r e s u lt s in seed pod dehiscen ce w h e th e r th e pods, a re f u l l y m ature
o r not .
D e s ic c a n ts and d e f o lia n t s a re n o t e x te n s iv e ly used in th e h a rv e s t
o f b ir d s f o o t t r e f o i l seed a t th e p re s e n t tim e .
W ig g in s , e t a l .
(46)
5
e x p e rim e n tin g w ith d e s ic c a n t sprays concluded t h a t "th e n a tu r a l v a r i ­
a b i l i t y o f c lim a t ic c o n d it io n s , e s p e c ia lly te m p e ra tu re and r e la t iv e
h u m id ity , w i l l a f f e c t seed pod d e h is c e n c e , re g a rd le s s o f th e h a rv e s t
m e th o d ."
W ie s n e r, e t a l . (4 5 ) fo u n d t h a t th e a p p lic a tio n o f a b s c is s ic
a c id , b e n z y la d e n in e , and g i b b e r e l lic a c id d id n o t a f f e c t seed o r fo ra g e
y ie ld o f 'L e o ' b ir d s f o o t t r e f o i l .
Some new seed h a rv e s tin g m achin ery has been developed f o r h a n d lin g
legume cro p s w h ich have a te n d e n cy t o lo d g e .
Vance (4 2 ) used a machine
w hich had a s ic k le t h a t c u t th e fo ra g e a t th e s o i l s u r fa c e .
T h is
m achine had a s tro n g vacuum, w hich f u n c tio n s j u s t o v e r and ahead o f th e
s ic k le and p u lls up th e f o li a g e , lo o s e seed heads, and s h a tte re d seed.
Vance (4 2 ) e s tim a te s t h a t t h i s m achine saved 98 p e rc e n t o f th e seed.
W ie s n e r,.e t a l .
(4 4 ) is
in v e s t ig a t in g th e use o f a. vacuum h a rv e s te r t o
p ic k up d e h isce d seed fro m th e s o i l s u r fa c e .
He has been a b le t o p ic k
up b ir d s f o o t t r e f o i l seed fro m th e s o i l s u r fa c e .
However, s e p a ra tin g
th e seed fro m tr a s h has been a p ro b le m .
H a rv e s tin g te c h n iq u e s and i r r i g a t i o n
c o n te n t o f b ir d s f o o t t r e f o i l
( I , 2 0 ).
t r e f o i l seed may be hard when f u l l y
in t e r v a ls in flu e n c e hard seed .
One-hundred p e rc e n t o f b ir d s f o o t ,
r ip e ; how ever, th e seed c o a t is
u s u a lly s c a r if ie d by th e th re s h in g a c tio n o f th e com bine.
Seed v i a b i l i t y
and g e rm in a tio n depends upon i t s m a tu r ity (tim e o f h a r v e s t ) , h a rv e s t
method * c le a n in g , p ro c e s s in g , and s to ra g e .
A bu-S hakre, e t a l .
(I)
re p o rte d t h a t hard seed c o n te n t o f a l f a l f a was in flu e n c e d by i r r i g a t i o n
6
in te r v a l.
Hard seed c o n te n t in c re a s e d w ith decreased i r r i g a t i o n f r e ­
quency.
Improvement o f Seed Y ie ld and P re v e n tio n
o f frod Dehiscence"
The la c k o f an e f f i c i e n t means f o r h a rv e s tin g b ir d s f o o t t r e f o i l
seed has prom pted e x te n s iv e b re e d in g to . in c re a s e seed y ie ld and p re v e n t
pod d e h is c e n c e .
Components o f seed y ie ld and a s s o c ia te d c h a r a c t e r is t ic s ,
( 2 , 9 ) , m o rp h o lo g ic a l and p h y s io lo g ic a l p la n t c h a r a c t e r is t ic s
(1 7 , 26)
have been s tu d ie d .
MacDonald (2 1 ) was th e f i r s t t o s tu d y th e r e la t io n s h ip o f p la n t
c h a r a c t e r is t ic s in b ir d s f o o t t r e f o i l t o seed developm ent and seed y i e l d .
S ince th e n , many w o rke rs have re p o rte d s im il a r s tu d ie s in many d i f f e r e n t
s p e c ie s .
S im ila r itie s
in agronom ic c h a r a c t e r is t ic s in flu e n c in g seed y ie ld
a re found among le g u m e .s p e c ie s .
T a y lo r , e t a l .
(3 9 ) re p o rte d t h a t t h e .
number o f heads p e r p la n t in red c lo v e r was th e p rim a ry f a c t o r g o ve rn in g
seed y i e l d .
ta n c e .
Number o f seeds p e r head and seed w e ig h t were o f le s s im por­
High y ie ld in g p ro g e n ie s were e a r l i e r th a n average t o f lo w e r .
Hawkins ( 1 6 ) , in E ngland, re p o rte d t h a t f a c to r s a f f e c t in g seed y ie ld o f
re d c lo v e r appear t o be number o f seeds s e t p e r head, seed s iz e , number
o f hea ds, and r e s is ta n c e t o d is e a s e .
Seed s e t , seed s iz e , and number o f
heads a re so c lo s e ly lin k e d t h a t d iffe r e n c e s in y ie ld a re in d ic a te d by
d iffe r e n c e s in any one o f th e s e c h a ra c te rs ( 1 6 ) .
7
Pedersen and Nye (3 1 ) measured seed y ie ld components in a l f a l f a f o r
th re e v a r i e t i e s .
! U in t a 1 had 8 .0 pods p e r racem e, 'R a n g e r' had 7 .4 ,
and ' L o h o n ta n ' had 6 . 7 .
' U in ta ' had 4 .1 seeds p e r pod,
4 . 0 , and ' L a h o n ta n 1 had 3 . 6 .
y ie ld s w ith
'R a n g e r' had
These r e s u lt s corre sp o n d t o a c tu a l seed
' U in ta ' b e in g th e h ig h e s t and ' Lah ontan' th e lo w e s t.
In
t h i s s tu d y , th e number o f flo w e rs p e r raceme in a l f a l f a was n o t s ig ­
n i f i c a n t l y a s s o c ia te d w ith seed y i e l d .
A lb r e c h ts e n , e t a l . (2 ) and B u z z e ll and W ils ie (9 ) re p o rte d t h a t
th e number o f umbels s e t t in g seed in b ir d s f o o t t r e f o i l had th e g r e a te s t
in flu e n c e upon seed y i e l d .
S tu d ie s in th e N o rth C e n tra l Region (26)
in d ic a te d t h a t th e p h e n o ty p ic c h a r a c t e r is t ic s c o r r e la te d w ith seed
y ie ld s were pods p e r um bel, and seeds p e r um bel.
These re s e a rc h e rs
suggest th a t, no s in g le indepe nden t v a r ia b le accounts f o r th e v a r ia t io n
in seed y ie ld s among c lo n e s grown in d i f f e r e n t lo c a tio n s .
B re s c ia n i
(6 ) in d ic a te s t h a t number o f umbels p e r p la n t and number o f pods p e r
umbel were s i g n i f i c a n t l y c o r r e la te d t o seed y i e l d .
Number o f seeds p e r
pod was a ls o s i g n i f i c a n t l y c o r r e la te d w ith seed y i e l d .
e t a l.
A lb re c h ts e n ,
(2 ) s t a te s , "seed y ie ld is th e end r e s u lt o f th e i n t e r r e l a t i o n ­
s h ip s o f many component f a c t o r s and th e e n v iro n m e n t."
Acknowledgment o f th e r e la t io n s h ip s among c h a ra c te rs t h a t a f f e c t
fo ra g e and seed y ie ld is necessary b e fo re s e le c tio n f o r improvement o f
b oth can be made.
8
Peacock and W ils ie (3 0 ) s e le c te d f o r v e g e ta tiv e v ig o r and seed s e t ­
t in g
in c lo n e s o f b ir d s f o o t t r e f o i l .
They d id n o t f in d an in c re a s e in
seed p ro d u c tio n in e it h e r o f th e f i r s t o r second r e c u r r e n t s e le c tio n ;
how ever, th e r e were in d iv id u a l second c y c le crosses w hich were s u p e rio r
in seed p r o d u c tio n .
They suggested t h a t c ro s s in g o f s e le c te d s u p e rio r
second c y c le p a re n ts shou ld g iv e in c re a s e s in seed s e t.
In a s im ila r s tu d y u s in g
'L e o ' b ir d s f o o t t r e f o i l and r e c u r re n t
s e le c t io n , Sandha, e t a l .
(3 4 ) were a b le t o in c re a s e seed y ie ld w ith
two c y c le s o f s e le c t io n .
The g e n o -p h e n o ty p ic method was s u p e rio r to th e
g e n o ty p ic m ethod.
They in d ic a te d t h a t f u r t h e r improvem ent w ith a d d i­
t io n a l c y c le s o f s e le c tio n shou ld be p o s s ib le w ith th e g e n o -p h e n o typ ic
m ethod.
Sandha, e t a l .
(3 5 ) a ls o used a p o ly -c ro s s progeny t e s t in g
method and found a s ig n if ic a n t a s s o c ia tio n between seed y ie ld and seed
s iz e , seeds p e r p o d , and pods p e r in flo r e s c e n c e .
The p o s it iv e c o r r e la ­
t io n between seed y ie ld and seed s iz e does n o t agree w ith e a r l i e r r e p o r ts
by Twamley (4 1 ) and A lb r e c h ts e n , e t a l .
(2 ).
G enetic v a r ia t io n . e x is t s f o r seed y ie ld
(9 ).
H e r e d it a b i lit y e s t i ­
mates suggest t h a t a la rg e p a r t o f p h e n o ty p ic v a ria n c e f o r seed s e t is
g e n e t ic a lly c o n t r o lle d ( 1 9 ) .
A lth o u g h s e le c tio n s f o r h ig h seed y ie ld s
have been in c o rp o ra te d in t o e x p e rim e n ta l s y n t h e t ic s , no v a r ie t ie s have
been developed s p e c i f i c a l l y f o r h ig h e r seed y ie ld s
(3 6 ).
Based on th e s e b re e d in g s tu d ie s t o in c re a s e seed y i e l d , i t appears
t h a t th e g e n e tic seed y ie ld p o t e n t ia l o f b ir d s f o o t t r e f o i l w i l l n o t be
9
r e a liz e d u n le s s an e f f i c i e n t method f o r p re v e n tin g pod dehiscen ce is
fo u n d .
In a d d it io n , W iesner,. e t a l . (4 5 ) r e p o r ts t h a t th e pods con­
t a in in g la rg e seed s h a t t e r f i r s t because th e y were th e f i r s t t o m a tu re ,
le a v in g o n ly th e sm a ll im m ature seeds on th e p la n t f o r h a r v e s tin g .
T h e re fo re , any s ig n i f i c a n t im provem ent in seed s iz e w i l l . b e reduced due
t o th e seed d e h is c e n t problem o f b ir d s f o o t t r e f o i l . .
'
S e le c tio n f o r r e s is ta n c e t o seed pod dehiscence in b ir d s f o o t t r e ­
f o i l was f i r s t a tte m p te d by Peacock and W ils ie ( 2 9 ) .
They found wide
d iffe r e n c e s in s u s c e p t i b i l i t y due t o pod dehiscence among c lo n e s .
Seed
pod d e h isce n ce was reduced 17 p e rc e n t w ith one s e le c tio n c y c le f o r
s h a tte r r e s is ta n c e .
An in t e r s p e c if ic - h y b r id iz a t io n s tu d y was undertaken
by P h i l l i p s and Keim ( 3 3 ) , in an a tte m p t t o in c o rp o ra te th e in d e h isce n t
seed pod c h a r a c te r o f L.. c o im b re n s is in t o th e a g ro n o m ic a lI y d e s ira b le
I. c o r n ic u la t u s ;
They noted t h a t pod deh isce n ce was d i r e c t l y a s s o c ia te d
w ith r e l a t i v e h u m id ity . . Crosses o f L. c o r n ic u la t u s w ith th e J_.
c o im b re n s is produce no seeds due to h ig h flo w e r drop and low p o lle n
fe r tility .
■ B ir d s fo o t t r e f o i l pods a re tough and do n o t s h a t t e r when th e
r e l a t i v e h u m id ity is above 35 p e rc e n t (2 5 , 32, 36, 4 0 ) .
(3 2 ) noted t h a t i r r i g a t i o n
/
P e te rs o n , e t a l .
is necessary t o m a in ta in a canopy o f new
1
grow th above most o f th e seed pods, w hich keeps th e h u m id ity h ig h enough
t o reduce seed pod d e h is c e n c e .
M e tc a lfe , e t a l .
(25) have done th e
m a jo r it y o f th e w ork w ith pod d e h is c e n c e , r e l a t i v e h u m id ity , and m o is tu re
10
e q u ilib r iu m .
The in c id e n c e o f pod d eh iscen ce is g r e a te s t when tem pera­
tu r e s a re h ig h and th e r e la t iv e h u m id ity is lo w .
They s tu d ie d th e
e f f e c t s o f v a r ia t io n s in r e l a t i v e h u m id ity on pod deh isce n ce and d e te r ­
mined th e m o is tu re e q u ilib r iu m between m ature pods
atm osphere.
F ie ld s tu d ie s were a ls o made t o measure te m p e ra tu re f l u c t u ­
a tio n s . b o th w it h in th e pod and on i t s
s u n lig h t .
and th e su rro u n d in g
s u rfa c e under d i r e c t and shaded
They fo u n d : .1 ) b ir d s f o o t t r e f o i l pods d e h is c e a t a p p ro x i­
m a te ly 30 p e rc e n t r e l a t i v e h u m id ity b u t n o t a t 35 p e r c e n t, and 2) th e
m o is tu re e q u ilib r iu m v a lu e o f th e pod a t 30 p e rc e n t r e l a t i v e h u m id ity
was 10.05 p e r c e n t, and a t 40 p e rc e n t r e l a t i v e h u m id ity , th e m o is tu re
e q u ilib r iu m was 10.49 p e r c e n t.
These v a lu e s suggest a v e r y c lo s e i n t e r ­
dependence o f r e l a t i v e h u m id ity , m o is tu re e q u ilib r iu m , and pod s h a t t e r .
These f i e l d
s tu d ie s in d ic a te d te m p e ra tu re s w it h in and a t th e s u rfa c e o f
m ature pods v a rie d as much as 12 degrees C. fro m th e a i r te m p e ra tu re
depending on c lo u d c o v e r.
The s t r u c t u r a l p a tte r n o f t is s u e s in b ir d s f o o t t r e f o i l pods is
r e la te d t o th e mechanism o f d e h is c e n c e .
B uckovic (7 ) s tu d ie d th e
a n a to m ic a l s t r u c t u r e o f b ir d s f o o t t r e f o i l pods and found t h a t th e pod
w a ll was composed o f tw o s e p a ra te la y e r s .
He.concluded t h a t m o is tu re
lo s s was th e g o v e rn in g f a c t o r in pod d eh iscen ce and p o s tu la te d t h a t th e
r a te o f m o is tu re lo s s d if f e r e d in th e two t is s u e s .
T h is r e s u lte d in
te n s io n s between in d iv id u a l la y e rs o f f ib e r s and p o s s ib ly in t h e i r com­
ponent f i b e r s .
As th e d r y down c o n tin u e d th e te n s io n overcomes th e .
11
cohe sion a t th e s u tu re s and th e two h a lv e s o f th e pod s e p a ra te and t w i s t
open.
Pods r e a d ily de h isce d when th e y had lo s t between 38 t o 6G p e rc e n t
o f t h e i r o r ig i n a l m o is tu re , b u t th e m o is tu re c o n te n t o f pods a t de­
h is c e n c e was n o t d e te rm in e d .
Pod m o is tu re , a t s h a tte r needs t o be d e te r ­
mined in o rd e r t o a id fa rm e rs in h a rv e s tin g o f b ir d s f o o t t r e f o i l seed.
These s tu d ie s sugg est t h a t seed p ro d u c tio n would be most s u c c e s s fu l
in g e o g ra p h ic a l areas where r e l a t i v e h u m id ity would be above 40 p e rc e n t.
In a d d it io n . Winch and MacDonald (4 8 ) recommended t h a t h a rv e s tin g shou ld
be g in when 70-80 p e rc e n t o f th e pods a re m a tu re , i . e . , when l i g h t brown
t o brow n.
However, Anderson (3 ) suggested s l i g h t l y e a r l i e r h a rv e s t,
"when maximum number o f pods a re l i g h t green t o l i g h t b ro w n ."
CHAPTER I
THE EFFECTS OF MISTING ON PHYSIOLOGICAL DEVELOPMENT,
POD DEHISCENCE, AND SEED YIELD OF BIRDSFOOT TREFOIL
( LOTUS CORNICULATUS L .)
In tr o d u c tio n
B ir d s fo o t t r e f o i l
legume (1 2 , 3 7 ) .
(L o tu s c o r n ic u la tu s L . ) is a v a lu a b le fo ra g e
I t s use has been lim it e d due t o p o o r s ta n d e s t a b lis h ­
ment and h ig h seed c o s t .
The h ig h seed c o s t is due t o low seed y ie ld s
w hich r e s u lt fro m seed pod d e h is c e n c e ,
Iem in humid th a n in a r id r e g io n s .
Pod dehiscence is
le s s o f a prob
However, seed p ro d u c tio n p o t e n t ia l
is g r e a te r in a r id re g io n s under i r r i g a t i o n due t o th e lo w e r in c id e n c e
o f d is e a s e (2 3 , 3 2 ).
The la c k o f an e f f i c i e n t means f o r h a rv e s tin g b ir d s f o o t t r e f o i l
seed has prom pted e x te n s iv e b re e d in g t o in c re a s e seed s e t , y i e l d , and
p re v e n t pod deh isce n ce ( 2 , 9 , 3 0 ) .
P la n t b re e d e rs have been unable t o
deve lo p in d e h is c e n t c u l t i v a r s o f b ir d s f o o t t r e f o i l (3 4 , 3 6 ) ; th u s
im provem ent in seed y ie ld must come fro m b e t t e r management.
M e tc a lfe , e t a l .
(2 5 ) fo u n d t h a t b ir d s f o o t t r e f o i l pods d e h isce
r e a d ily a t 30 p e rc e n t r e l a t i v e h u m id ity b u t n o t a t 40 p e r c e n t.
M o is tu re
e q u ilib r iu m o f pods a t th e s e r e l a t i v e h u m id ity le v e ls was 10.05 p e rc e n t
and 10.39 p e r c e n t, r e s p e c t iv e ly .
They re p o rte d a c lo s e r e la t io n s h ip
between r e l a t i v e h u m id ity and m o is tu re c o n te n t a t tim e, o f pod dehiscence
13
In th e d r y areas o f th e w e ste rn U nited. S ta te s , i t may be p o s s ib le
t o p re v e n t pod deh isce n ce th ro u g h p e r io d ic w e ttin g o f th e b ir d s f o o t
t r e f o i l canopy w ith s p r in k le r i r r i g a t i o n .
The o b je c t iv e o f t h i s stu d y
was t o d e te rm in e th e e f f e c t s o f v a rio u s m is tin g le v e ls on pod dehiscence
and seed y ie ld o f b ir d s f o o t t r e f o i l .
M a te r ia ls and Methods
A one-ha seed f i e l d
o f l T re ta n a l b ir d s f o o t t r e f o i l was p la n te d in
1978 a t th e F ie ld Research L a b o ra to ry , Bozeman, MT, in t o a Bozeman s i l t
loam ( A rg ic -P a c h ic C ry o b o ra lI ) s o i l .
Seeding r a te was 2 .2 5 kg /h a pure
l i v e seed w ith rows spaced 0 .6 m a p a r t.
The e f f e c t s o f th re e m is tin g
tre a tm e n ts and f o u r h a rv e s t da te s on seed y ie ld o f b ir d s f o o t t r e f o i l were
s tu d ie d u s in g a s p lit- p lo t- r a n d o m iz e d - c o m p le te - b lo c k d e s ig n w ith th re e
r e p li c a t io n s .
Main p lo t s w ere:
I ) no m is t in g , 2) tw ic e d a i ly m is tin g
(10AM and 3PM), and 3 ) h o u r ly m is tin g (8AM t o 6PM).
da te s were c o n s id e re d th e s u b - p lo ts .
The f o u r h a rv e s t
In 1979, seed pods m atured r a p id ly
due t o an u n u s u a lly h o t , d ry summer and seed was h a rv e s te d a t 7-day
in t e r v a ls s t a r t in g on J u ly 27.
In 1980, seed pods m atured s lo w ly due
t o an a b n o rm a lly c o o l, w et summer w hich r e s u lte d in h a rv e s t dates o f
August 2 5 , September 4 , September 15, and O ctober 2 .
P
P lo ts were 9 .1 4 m w ith a 6.1 m b o rd e r between p lo t s w it h in r e p l i ­
c a t io n s .
R e p lic a tio n s were se p a ra te d by a minimum o f a 15 .2 m b o rd e r.
These b o rd e rs in s u re d a g a in s t i r r i g a t i o n o v e rla p d u rin g w indy c o n d i­
t io n s .
14
Sencor [ 4 - a m in o - 6 - t e r t - b u t y l- S ^ m e th y lt h io ) - a s - t r ia z in - 5 ( 4 H ) - o n e ]
was a p p lie d a t .68 kg /h a a c t iv e in g r e d ie n t in th e s p rin g o f 1979 and
1980 t o c o n t r o l weeds.
The i r r i g a t i o n
system c o n s is te d o f 9 .1 4 m s e c tio n s o f p o ly v in y l­
c h lo r id e (PVC) p ip e jo in e d by PVC c o u p le rs and e lb o w s.
Model P-J25
R a in b ird s p r in k le r heads w ith 0.397 cm n o z z le opening were a tta c h e d to
1 .9 x 9 2 .0 cm g a lv a n iz e d r is e r s
lo c a te d in th e c o rn e r o f each p l o t .
Each s p r in k le r head m is te d a q u a r te r c i r c l e w ith th e s p ra y d is ta n c e
(9 .1 4 m) c o n t r o lle d by an a d ju s ta b le aluminum f l a p .
C
f o r 3 m in u te s a t 3.4 5 x 10
P lo ts were w atered
p
Newtons m
(SO p s i) p re s s u re .
Time o f
a p p lic a tio n f o r in d iv id u a l p lo t s was c o n t r o lle d by g a te v a lv e s .
were m is te d d a i ly
(e x c e p t when i t
P lo ts
ra in e d ) fro m J u ly 27 t o August 17 in
1979, and fro m August 25 t o O ctob er 2 in 1980.
p
A t each h a rv e s t d a te , I m areas were random ly chosen w it h in each
m is tin g tre a tm e n t and 15 random ly s e le c te d stems were c o lle c t e d from
w it h in th e area f o r d e t a ile d m o rp h o lo g ic a l c h a r a c t e r iz a t io n .
The r e ­
m a in in g v e g e ta tio n was th e n h a rv e s te d a t ground le v e l, sa c k e d , a ir - d r ie d
f o r 30 d a y s , and th e seed cle aned w ith a b e l t th ra s h e r ( w ith o u t a i r ) ,
s ie v e s , and an Oregon c o n tin u o u s b lo w e r.
Clean seed was weighed and
kg /h a y ie ld of. seed c a lc u la te d .
Data c o lle c t e d fro m th e 15 random ly s e le c te d stem s, fro m each p l o t ,
in c lu d e d th e number o f b u d s/ste m , f lo w e r in g um bels/stem (no pods), f e r t i ­
liz e d um bels/stem (um bels w ith p o d s ), pod c o lo r , n o n -s h a tte re d p o d s/ste m .
15
s h a tte re d pods/stem (and t h e i r p o s it io n on each s te m ), t o t a l number o f
p o d s/ste m , t o t a l w et f r u i t w e ig h t/s te m , t o t a l a i r d r ie d f r u i t w e ig h t/
stem , and f r u i t m o is tu rp p e rce n ta g e ( a i r d ry b a s is ) a t h a rv e s t (1979
o n ly ) .
Pod c o lo r was de te rm in e d u s in g a M u nsell (2 8 ) c o lo r c h a r t f o r
v e g e ta tiv e p la n t t is s u e .
Pods were c l a s s if ie d in t o f o u r c a te g o r ie s :
d a rk g re e n -p u rp le (Hue 2.5R 3 /6 - Hue 5 G Y 6 /8 ), l i g h t green (Hue 2 .5
G Y 8/6), ta n (Hue 5 Y 8 /4 ), and brown (Hue 5Y R 4/5).
A t each h a rv e s t d a te
th e t o t a l number o f pods in each c o lo r c a te g o ry was re c o rd e d .
P e rcen t
pods in each c a te g o ry was d e te rm in e d by d iv id in g th e number o f pods in
t h a t c a te g o ry by th e t o t a l number o f pods ( in c lu d in g s h a tte re d pods)
and m u lt ip ly in g by 100.
P o s itio n o f s h a tte re d pods was re co rd e d by d iv id in g th e stem in to
q u a rte rs .
S h a tte re d pods in th e to p q u a r te r were a ssigned a v a lu e o f
one and s h a tte re d pods below th e to p q u a r te r were g iv e n a v a lu e o f tw o .
M o is tu re p e rce n ta g e a t h a rv e s t was dete rm in e d by s u b tr a c tin g a i r
d ry f r u i t w e ig h t, a f t e r 30 days o f d r y in g , fro m w et f r u i t w e ig h t,
d iv id in g by a i r d ry f r u i t w e ig h ty and m u lt ip ly in g by 100.
Seed q u a li t y was d e te rm in e d in th e la b o r a to r y f o r each m is tin g h a rv e s t d a te c o m b in a tio n tre a tm e n t.
Four groups o f 100 seeds from each
tre a tm e n t and h a rv e s t d a te were s u rfa c e s t e r i l i z e d
(0.1% NaOCl o r
T e tra c h lo ro -p a ra b e n z o q u i non e, 98 p e r c e n t) , p la ce d in p l a s t i c g e rm in a tio n
boxes on m o is t b l o t t e r p a p e r, and g e rm in a te d in a d a rk g e rm in a to r a t
16
20 C.
Seeds were w a tered as needed.
A f t e r 12 days co u n ts were taken
on th e number o f g e rm in a te d , a b n o rm a l, h a rd , and dead seeds.
p le t e ly . random d e sig n w ith f o u r r e p lic a t io n s was used.
were p la c e d in th e g e rm in a to rs on c o n s e c u tiv e d a ys.
A com­
R e p lic a tio n s
One hundred seed
w e ig h t f o r each tre a tm e n t and h a rv e s t d a te was d e te rm in e d .
Data were analyzed u s in g a n a ly s is o f v a ria n c e f o r a s p l i t - p l o t
random ized com ple te b lo c k d e sig n and means Were se p a ra te d w ith Duncan's
New M u lt ip le Range T e s t ( 3 8 ) .
R e s u lts and D is c u s s io n
E n viro n m e n ta l c o n d itio n s in 1979 were id e a l f o r b ir d s f o o t t r e f o i l
seed p ro d u c tio n (T a b le I ) .
The d r y , h o t c o n d itio n s r e s u lte d in an e x­
c e lle n t en viro n m e n t f o r h ig h seed p ro d u c tio n and pod d e h is c e n c e .
M is tin g s i g n i f i c a n t l y changed flo w e r and seed m a tu ra tio n c h a r a c te r ­
is t ic s
in c lu d in g number o f b u d s, number o f brown pods, t o t a l number o f
pod s, number o f s h a tte re d pod s, pod m o is tu r e , and seed y ie ld
M is tin g d id n o t a f f e c t number o f f lo w e r in g and f e r t i l i z e d
(T a b le 2 ) .
um bels, and
th e number o f d a rk g re e n , l i g h t green and ta n pods (T a b le 2 ) .
S ig n ifi­
c a n t d iffe r e n c e s among h a rv e s t da te s were d e te c te d f o r a l l t r a i t s , e x ­
c e p t number o f flo w e r in g gnd f e r t i l i z e d
umbels and number o f ta n pods
(T a b le 3 ) .
M is tin g caused in c re a s e d bud p ro d u c tio n a t th e l a t e r stages o f seed
m a tu ra tio n (T a b le s 2 and 3 ) .
However, n o n s ig n if ic a n t d iffe r e n c e s among
m is tin g tre a tm e n ts and h a rv e s t d a te s f o r number o f f lo w e r in g and
17
T able I .
W eather summary f o r 1979-80 a t Bozeman, MT.
Maximum
Tem perature
Mean
Minimum
Tem perature
A ccu m ulation
P r e c ip it a t io n
3 0 - y r A vg.
May
17.39
3.61
65.25 .
1979
May .. .
17.78
3.8 9
58.25
May
18.94
5 .2 8
142.00
3 0 -y r A vg.
June
21.22
7.17:
81.75
1979
June
23.50
8 .4 4
91.50
1980
June
20.11
7.83
71.25
3 0 - y r A vg.
J u ly
27.50
10.61
29.75
1979
J u ly
28.50
11.39
14.75
1980
J u ly
27.50
11.28
28.00
3 0 -y r Avg.
August
26.83
9.67
29.75
1979
August
27.06
11.17
37.75
1980
August
24.78
9.0 0
46.25
3 0 - y r Avg. .
September
20.83
5 .2 8
44.00
1979
September
26.61
7.33
1.75
1980
September
21.22
6.50
. 85.00
3 0 - y r Avg.
O ctober
14.83
7.7 8
1152.50
1979
O ctober
17.22
2.3 3
38.50
1980
O ctober
15.44
1.06
18.25
1980
'
18
Table 2 .
The e f f e c t s o f th re e m is tin g tre a tm e n ts upon seed y ie ld
components o f b ir d s f o o t t r e f o i l a t Bozeman, MT, 1979.
M o rp h o lo g ic a l
C h a r a c te r is tic s
None
Buds (N o .)
0 .0 8 ca
1.08 b
1.92 a
F low er Umbels (N o .)
0 .0 0
0 .0 8
0.25
F e r t ili z e d Umbels (N o .)
5 .4 0
6.4 0
5.6 0
Dark Green Pods (N o .)
2 .7 0
7.90
6.50
L ig h t Green Pods (N b .)
2 .6 0
2.8 0
2.90
Tan Pods (N o .)
1.20
1.30
1.40
3 .4 0 b
8 .3 0 a
8 .2 0 a
10.10 b
20.20 a
17.00 a
5 .6 0 a
0.9 0 b
0.8 0 b
33.60 b
51.00 a
58.30 a
294.00 b
554.00 a
551.00 a
Brown Pods (N o .)
.
T o ta l Pods (N o .)
S h a tte re d Pods (N o .)
Pod M o is tu re (%)
Seed Y ie ld (k g /h a )
M is tin g Treatm ents
Twice D a ily
.
H o urly.
aMeans in th e same row fo llo w e d by th e same l e t t e r a re n o t s ig ­
n i f i c a n t l y d i f f e r e n t by Duncan's m u lt ip le Range T e st a t p = .05 l e v e l .
19
T able 3 .
The e f f e c t s o f f o u r h a rv e s t d a te s upon seed y ie ld components
o f b ir d s f o o t t r e f o i l a t Bozeman, MT, 1979.
M o rp h o lo g ic a l
C h a r a c te r is tic s
H a rve st Dates
August 3
August 10
J u ly 27
August 17
Buds (N o .)
0 .6 7 ba
0.11 b
I , .11 ab
2.22 a
F lo w e rin g Umbels (N o .)
0.3 3
0.11
0,.11
0.0 0
F e r t ili z e d Umbels (N o .)
5.3 0
6 .3 0
6;.00
5.50
Dark Green Pods (N o .)
9.5 0 a
9 .7 0 a
2..10 b
1.40 b
L ig h t Green Pods (N o .)
4.7 0 a
3 .90 ab
I, .60 ab
0.80 b
Tan Pods (N o .)
1.00
1.70
I , .30
1.10
Brown Pods (N o .)
0 .8 0 b
3 .1 0 b
10,.70 a
9.30 a
T o ta l Pods (N o .)
15.90 ab
18.40 a
15,.60 ab
13.00 b
3,.00 b
5.2 0 a
60.10 a
28,.10 b
34.10 b
510.00 a
567,.00 a
467.00 ac
S h a tte re d Pods (N o .)
Pod M o is tu re (%)
Seed Y ie ld (k g /h a )
0 .0 0
C
68.20 a
320.00
C
1.60 be
aMeans in th e same row fo llo w e d by th e same l e t t e r a re n o t s ig ­
n i f i c a n t l y d i f f e r e n t by Duncan's M u lt ip le Range T e st a t p = .05 le v e l.
20
f e r t iliz e d
umbels (T a b le s 2 and 3 ) in d ic a te flo w e r d ro p p ro b a b ly o c c u rre d
and th e s e in c re a s e d buds d id n o t r e s u lt in in c re a s e d seed y ie ld s .
E v i­
d e n tly flo w e r s were n o t p o llin a t e d o r th e en viro n m e n t was n o t conducive
t o seed developm ent o f new ly form ed pods d u rin g th e m is tin g p e r io d .
The g r e a te s t number o f d a rk green pods were d e te c te d e a r ly in th e
season and d e c lin e d w ith m a tu ra tio n (T a b le 3 ) .
T h is decrease was due
to ' m a tu ra tio n o f green pods and f a i l u r e o f new pods t o d e v e lo p .
A s im i­
l a r r e la t io n s h ip was d e te c te d f o r l i g h t green pods, b u t o f a le s s e r
m agnitude (T a b le 3 ) i
M is tin g tre a tm e n ts g r e a t ly in c re a s e d th e p e rce n ta g e o f brown pods
w ith in c re a s in g m a tu r ity (F ig u re I ) .
in g .
y ie ld .
T h is was due t o decreased s h a t t e r ­
M is tin g tw ic e d a i ly reduced pod d eh iscen ce and in c re a s e d seed
A d d itio n a l w e ttin g de la ye d pod m a tu ra tio n and decreased y ie ld s .
H o u rly m is tin g o f b ir d s f o o t t r e f o i l r e s u lte d in a maximum o f 55 p e rc e n t
brown pods (F ig u re I ) , whereas m is tin g tw ic e d a i ly r e s u lte d in 70Lpercent
brown pods (F ig u re I ) .
Seventy p e rc e n t brown pods were o b ta in e d on th e
same h a rv e s t d a te (A ugust 10) as th e maximum seed y ie ld was produced.
The 70 p e rc e n t brown pod sta g e c o u ld be used by seed p ro d u ce rs t o
d e te rm in e tim e o f h a r v e s t, i f
a m is tin g program was b e in g used.
This
v a lu e would r a r e ly be o b ta in e d w ith o u t m is tin g under warm, d ry c o n d itio n s
because pod s h a t t e r would o c c u r f i r s t .
The p e rcen tag e o f brown pods
was s i g n i f i c a n t l y c o r r e la te d t o t o t a l seed y ie ld
( r = 0 .4 5 * * ).
21
Trt 2
T rt I -n o mist
T rt2 -tw ic e daily
Trt 3 -h o u rly
JUL 2 7
AUG 3
AUGIO AUG 17
HARVEST DATES
F ig u re I .
The e f f e c t s o f th re e m is tin g t r e a t ­
ments and f o u r h a rv e s t dates upon
p e rc e n t brown pods o f b ir d s f o o t t r e ­
f o i l a t Bozeman, MT, 1979.
♦Means in th e same row fo llo w e d by
th e same l e t t e r a re n o t s i g n i f i c a n t l y
d i f f e r e n t by Duncan's M u lt ip le Range
T e s t a t p = .05 le v e l.
22
T w ic e - d a ily and h o u r ly m is tin g in c re a s e d t o t a l number o f pods
(T a b le 2 ) , and t h i s f a c t o r was s i g n i f i c a n t l y c o r r e la te d w ith seed y ie ld
a t a l l h a rv e s t d a te s e x c e p t th e h a rv e s t on J u ly 2 7 .
f o r h a rv e s t d a te s o f August 3 , 10, and 17 w ere:
0 .7 6 * * , r e s p e c t iv e ly .
The c o r r e la t io n s
r = 0 0 6 7 **, 0 . 8 1 * * , and
The in c re a s e d number o f brown pod s, t o t a l number
o f p o d s , and seed y ie ld r e s u lte d fro m a decrease in pod dehiscen ce due
t o ’ m is tin g (F ig u re 2 ) .
Pod deh isce n ce in c re a s e d w ith m a tu r ity f o r a l l
tre a tm e n ts and was h ig h e s t f o r th e n o n -m iste d tre a tm e n t (70 p e r c e n t) .
Pod d eh iscen ce f o r th e m is tin g tre a tm e n ts d id n o t exceed 12 p e r c e n t.
The number o f s h a tte re d pods was n e g a tiv e ly c o r r e la te d ( r = - 0 .7 2 * * )
w ith seed y ie ld on August 17.
M is tin g in c re a s e d pod m o is tu re ( F ig u re 3) and p re v e n te d pod de­
h is c e n c e .
Pod m o is tu re was s i g n i f i c a n t l y c o r r e la te d w ith seed y ie ld on
August 10 and 17. ( 0 .7 5 * * and 0 .6 7 * * , r e s p e c t iv e ly ) .
M is tin g tw ic e d a i ly in c re a s e d seed w e ig h t (T a b le 4 ) due t o th e r e ­
t e n t io n o f h e a v ie r seed.
In c o n t r a s t , h e a v ie r seed s h a tte re d in th e .
n o n -m is te d b ir d s f o o t t r e f o i l tre a tm e n ts and co u ld n o t be h a rve ste d ( 4 4 ) .
M is tin g in c re a s e d seed y ie ld by p re v e n tin g pod d eh iscen ce and i n ­
c re a s in g seed w e ig h t o f h a rv e s te d seed (F ig u re 4 ) .
The seed y ie ld ob­
ta in e d on August 10 f o r th e m is tin g tre a tm e n ts is in d ic a t iv e o f m axi­
m iz in g seed p ro d u c tio n w h ile m in im iz in g pod d e h isce n ce .
No s ig n if ic a n t
d iffe r e n c e s were d e te c te d between th e tw ic e d a i ly and h o u r ly mi s t in g s . .
23
T rt I -n o mist
T rt 2 -tw ic e daily
Trt 3 -h o u rly
Trt J> b
Trt2
JUL 2 7
AUG 3 AUGIO AUG17
HARVEST DATES
F ig u re 2 .
The e f f e c t s o f th re e m is tin g t r e a t ­
ments and f o u r h a rv e s t da te s upon
p e rc e n t s h a tte re d pods o f b ir d s f o o t
t r e f o i l a t Bozeman, MT, 1979.
*Means in th e same row fo llo w e d by
th e same l e t t e r are n o t s i g n i f i c a n t l y
d i f f e r e n t by Duncan's M u lt ip le Range
T est a t p = .05 le v e l.
24
Trt I - no m ist
T rt 2 -tw is t daily
Trt 3 -h o u riy
Trt 3
S 50
Z 30
JUL 27
AUG 3
AUGIO
AUG17
HARVEST DATES
F ig u re 3 .
The e f f e c t s o f th re e m is tin g t r e a t ­
ments and f o u r h a rv e s t dates upon
p e rc e n t pod m o is tu re o f b ir d s f o o t
t r e f o i l a t Bozeman, MT, 1979.
*Means in th e same row fo llo w e d by th e
same l e t t e r a re n o t s i g n i f i c a n t l y
d i f f e r e n t by Duncan's M u lt ip le Range
T e st a t p = .05 l e v e l .
25
T able .4.
The e f f e c t s o f th re e m is tin g tre a tm e n ts upon t o t a l seed w e ig h t
p e r 100 seed a t f o u r h a rv e s t da te s o f b ir d s f o o t t r e f o i l a t
Bozeman, MT, '1979.
M is tin g
T reatm ents
J u ly 27
" August 3
August 10
. August 17
0.82 b
None
1.90
1.78
1.22 b *
Twice d a ily
1.49
0 .1 9
5.9 8 a
■4.21 a ■
H o u rly
1.77
2.93
4.46 ab
3.80 ab
Means in the. same row fo llo w e d by th e same l e t t e r a re n o t sig -.
n i f i c a n t l y d i f f e r e n t by Duncan's M u lt ip le Range T e st a t p = .05 l e v e l .
26
T rt 2.
q
40
W 30
Trt I -n o moist
T rt2 -tw ic e daily
Trt 3 -hourly
JUL 2 7 AUG 3
AUGIO AUG17
HARVEST DATES
F ig u re 4 .
The e f f e c t s o f th re e m is tin g t r e a t ­
ments and f o u r h a rv e s t dates upon
seed y ie ld (Kg/H a) o f b ir d s f o o t t r e ­
f o i l a t Bozeman, MT, 1979.
*Means fo llo w e d by th e same l e t t e r
are n o t s i g n i f i c a n t l y d i f f e r e n t a t
th e .05 le v e l a c co rd in g to Duncan's
M u lt ip le Range T e s t.
27
t w ic e d a i ly m is tin g was una ble t o p re v e n t brown pods fro m s h a tte r in g
between A ugust 10 and 17.
Seed v i a b i l i t y was n o t a ffe c te d by m is tin g tw ic e d a i ly
(T a b le 5 ) ;
b u t th e h o u rly m is tin g decreased v i a b i l i t y due t o e x c e s s iv e m o is tu re
w hich caused seed g e rm in a tio n in th e f i e l d .
caused fu n g a l grow th w it h in and on seed pod s.
The h o u rly m is tin g a ls o
Seed v i a b i l i t y
in cre a se d
w ith l a t e r h a rv e s ts ( T a b le ,6 ) .
Sencor may have re p re sse d th e v e g e ta tiv e grow th and m a tu ra tio n o f
b ir d s f o o t t r e f o i l in 1980.
M a tu ra tio n was f u r t h e r dela ye d by c o o l, wet
c o n d itio n s in August and September o f 1980 (T a b le I ) .
The f i r s t h a rv e s t
in 1980 was August 25 as compared t o J u ly 27 in 1979.
The co m b in a tio n
o f Sencor damage and e n viro n m e n t se e m in g ly reduced seed y ie ld s in 1980.
( F ig u re 5 ) .
The e f f e c t s o f m is tin g tre a tm e n ts on f lo w e r in g and seed
m a tu ra tio n c h a r a c t e r is t ic s were g e n e r a lly n o n - s ig n if ic a n t .
Seed y ie ld s
in 1980 were decreased due t o m is tin g tre a tm e n ts , in d ic a t in g t h a t m is tin g
sh o u ld n o t have o c c u rre d as i t f u r t h e r dela ye d pod m a tu ra tio n .
In 1979 pod m o is tu re was r e la te d t o pod dehiscence and was in cre a se d
by m is t in g .
L ig h t m is tin g p re ve n te d m ature pods from d e h is c in g w h ile
im m ature pods d e ve lo p e d .
Maximum seed y ie ld s were o b ta in e d by m is tin g
tw ic e d a i ly and h a rv e s tin g when 70 p e rc e n t o f th e pods a re brown (August
10, 1 9 7 9 ).
The tw ic e d a i ly m is tin g o f b ir d s f o o t t r e f o i l had s i g n i f i ­
c a n t ly b e t t e r seed g e rm in a tio n th a n d id h o u r ly m is t in g , in d ic a tin g t h a t
e x c e s s iv e m o is tu re r e s u lt s in po o r seed v i a b i l i t y .
T h e re fo r e , seed
28
T able 5 . The e f f e c t s o f th re e m is tin g tre a tm e n ts '
upon p e rc e n t v i a b i l i t y o f seed lo t s o f b ir d s f o o t
t r e f o i l a t Bozeman, MT, 1979.
T reatm ent
P e rcen t V i a b i l i t y
1
80.97 a
2
73.23 a
3
54.43 b
*
.
Means fo llo w e d by th e same l e t t e r a re n o t s ig ­
n i f i c a n t l y d i f f e r e n t a t th e .05 le v e l a c c o rd in g t o
Duncan's M u lt ip le Range T e s t.
T able 6 .
The e f f e c t s o f f o u r h a rv e s t da te s on p e r ­
c e n t v i a b i l i t y o f seed lo t s o f b ir d s f o o t
t r e f o i l a t Bozeman, MT, 1979.
H a rve st Dates
P e rce n t V i a b i l i t y
J u ly 27
54.35 b
August 3
59.95 a
August 10
76.84 a
August 17
77.05 a
Means fo llo w e d by th e same l e t t e r a re n o t s ig ­
n i f i c a n t l y d i f f e r e n t a t th e .05 le v e l a c c o rd in g t o
Duncan's M u lt ip le Range T e s t.
29
-T r t2
AUG25 SPT 4
SPT 15 OCT 2
HARVEST DATES
F ig u re 5 .
The e f f e c t s o f th re e m is tin g tre a tm e n ts
and f o u r h a rv e s t d a te s upon seed y ie ld
(Kg/H a) o f b ir d s f o o t t r e f o i l a t Bozeman,
MT, 1980.
30
p ro d u ce rs sh o u ld a p p ly o n ly enough w a te r t o p re v e n t pod d e h isce n ce .
It
is p o s s ib le t h a t d a i ly m is tin g w ould have been s u f f i c i e n t .
- A lth o u g h m is tin g o f th e b ir d s f o o t t r e f o i l canopy tw ic e d a i ly m axi­
mized seed y ie ld s , seed p ro d u ce rs must base th e i r r i g a t i o n schedule on
th e e n v iro n m e n ta l c o n d itio n s p r e s e n t.
When e n v iro n m e n ta l c o n d itio n s a re
such t h a t pod d e h iscen ce w i l l n o t o c c u r, m is tin g o f pods w i l l n o t in ­
crease seed y i e l d .
When p ro d u c in g b ir d s f o o t t r e f o i l seed in an area w h ich has low
r e l a t i v e h u m id ity and m is tin g is used, I suggest t h a t I ) s t a r t m is tin g
when brown pod m o is tu re d e c lin e s t o a p p ro x im a te ly 10 p e rc e n t as in d ic a te d
in C hapter I I ,
2) m is t tw ic e d a i ly o r .a s needed t o p re v e n t s h a t t e r ,
3) swath when th e e n v iro n m e n ta l c o n d itio n s d ic t a t e o r a t a p p ro x im a te ly
70 p e rc e n t brown pod s ta g e , and 4) combine as soon as fo ra g e w i l l pass
th ro u g h com bine.
I f e n v iro n m e n ta l c o n d itio n s a re such t h a t w et c o o l
c o n d itio n s m ig h t p r e v a il la t e in th e season, I a d v is e com bining p r io r
t o th e 70. p e rc e n t brown pod s ta g e .
We have observed t h a t fre q u e n t
w e ttin g o f th e b ir d s f o o t t r e f o i l canopy produces a le a th e r y , tough pod
w hich does n o t s h a t t e r as r e a d ily as n o n -m iste d pods.
CHAPTER I I
THE RELATIONSHIP OF MOISTURE PERCENTAGE OF POD, SEED,
AND FRUIT AT DEHISCENCE OF BI RDSFOOT TREFOIL
(LOTUS CORNICULATUS L .)
In tr o d u c tio n
M is tin g b ir d s f o o t t r e f o i l pods d u rin g seed m a tu ra tio n reduced seed
s h a tte r and in c re a s e d seed y ie ld
(C h a p te r I ) .
Seed y ie ld was in crea sed
t h r e e - f o ld by tw ic e d a i ly m is tin g s (3 -m in u te p e rio d s ) f o r 2 weeks b e fo re
h a r v e s tin g .
However, t o use a m is tin g program e f f e c t i v e l y seed p rodu cers
need a means o f d e te rm in in g when pod d eh iscen ce w i l l o c c u r in th e f i e l d .
P re vio u s s tu d ie s have a tte m p te d t o r e la t e tim e o f h a rv e s t o f b ir d s ­
f o o t t r e f o i l . s e e d t o s p e c if ic m o rp h o lo g ic a l stages o f g row th (3 , 7, 4 8 ) .
These s tu d ie s de te rm in e d th e stages o f pod m a tu ra tio n and seed d e v e lo p ment w h ich would m axim ize seed y ie ld by h a rv e s tin g p r i o r t o seed pod
d e h is c e n c e .
A tte m p ts t o p re v e n t pod deh isce n ce w h ile im m ature pods r ip e n
have n o t p r e v io u s ly been re c o rd e d .
In a d d it io n , v a rio u s c u l t u r a l p ra c ­
t ic e s t h a t a l t e r p la n t g row th c h a r a c t e r is t ic s have been employed in
a tte m p ts t o in c re a s e seed y ie ld
(4 , 14, 18, 36, 46, 4 7 ) .
L im ite d suc­
cess has been achieved in in c re a s in g seed y ie ld th ro u g h im plem enting
th e s e v a rio u s c u l t u r a l p r a c t ic e s .
There is a c lo s e in te rd e p e n d e n ce between e n v iro n m e n t, m o is tu re
e q u ilib r iu m , and pod s h a t t e r ( 4 , 23, 2 5 ) .
M e tc a lfe , e t a l .
(2 5 ) found
t h a t b ir d s f o o t t r e f o i l pods w i l l d e h is c e r e a d ily a t 30 p e rc e n t r e la t iv e
.
32
h u m id ity b u t n o t a t 40 p e rc e n t.
M o is tu re e q u i l i b r i a o f pods a t th e se
r e l a t i v e h u m id ity le v e ls was 10.05 and 10.39 p e r c e n t, r e s p e c t iv e ly .
There a re s e v e ra l problem s in v o lv e d w ith m is tin g o f b ir d s f o o t t r e ­
f o i l such a s:
I ) do pods w ith v a rio u s g e n e tic m a te ria l s h a t t e r a t d i f ­
f e r e n t m o is tu re le v e ls , 2) a t what p e rce n ta g e m o is tu re shou ld m is tin g
b e g in , and 3) what is th e r e la t io n s h ip o f f r u i t , seeds, and pod m o is tu re
a t d e h is c e n c e .
The o b je c tiv e s o f t h i s s tu d y were t o d e te rm in e :
I) i f
d i f f e r e n t b ir d s f o o t t r e f o i l c lo n e s d e h is c e a t th e same percen tag e
m o is tu re , and 2) i f
seed p ro d u ce rs c o u ld d e te rm in e when t o beg in m is tin g
b ir d s f o o t t r e f o i l by d e te rm in in g pod m o is tu re p e r io d ic a lly .
M a te r ia ls and Methods
1
11
,
........ —
"
E v a lu a tio n o f Clones f o r Per­
centage M o is tu re a t Dehiscence
M ature brown pods were random ly s e le c te d from f o u r d i f f e r e n t clo n e s
o f b ir d s f o o t t r e f o i l f o r e v a lu a tio n o f seed pod dehiscen ce in 1980.
The
f o u r c lo n e s were o b ta in e d fro m a 50 c lo n e , t h i r d c y c le r e c u r r e n t s e le c ­
t io n p o ly c ro s s grown in th e greenhouse.
Fresh w e ig h t o f in d iv id u a l brown pods was o b ta in e d by w e ig h in g each
pod. t o th e n e a re s t o n e -te n th m illig r a m a t tim e o f h a r v e s t.
A p le x ig la s s
e n v iro n m e n ta l box (L shaped) was c o n s tru c te d u s in g a s m a ll s q u ir r e l cage
fa n and tw o p le x ig la s s cham bers.
v id e a i r c i r c u l a t i o n .
The box was open a t b o th ends t o p ro ­
An e x te r n a l h e a te r was p la ce d o u ts id e o f th e
lo w e r p o r t io n t o p ro v id e warm a i r (20°C ) f o r d r y in g pod s.
Sm all n y lo n
33
mesh bags ( 5 x 5
cm) were c o n s tru c te d t o h o ld th e in d iv id u a l pods f o r
dry-dow n and d e h is c e n c e .
These bags were, hung from s m a ll m etal rods
p la ce d acro ss th e 3 -in c h w id th o f th e upper exha ust chamber.
A c o m p le te ly random d e sig n w ith 16 r e p lic a t io n s was used.
A t pod
d e h is c e n c e ,.s e e d s and pod were removed from th e e n v iro n m e n ta l chamber
and weighed im m e d ia te ly .
M o is tu re p e rce n ta g e a t s h a tte r was c a lc u la te d
on an a i r d ry b a s is .
R e la tio n s h ip o f F r u i t , Seeds, and
Pod M o is tu re a t Dehiscence
M o is tu re p e rce n ta g e o f f r u i t ,
seeds, and pod was measured t o d e te r ­
mine m o is tp re c o n te n t a t . t im e o f d e h is c e n c e .
Brown f r u i t samples were ta ke n fro m
p la n ts grown on a Bozeman s i l t
l T re ta n a l b ir d s f o o t t r e f o i l
loam ( A rg ic -P a c h ic C ry o b o ra lI ) s o i l a t
th e F ie ld Research L a b o ra to ry , Bozeman, MT.
Samples were ta k e n t o th e
la b o r a to r y in a c o o le r and e v a lu a te d f o r m o is tu re c o n te n t a t tim e o f
d e h is c e n c e .
Brown f r u i t random ly s e le c te d were p la ce d in w e ig h in g
b o t t le s and fr e s h f r u i t w e ig h ts re c o rd e d .
Each f r u i t was removed from
th e w e ig h in g b o t t l e , p la c e d in a sm a ll mesh bag, and a llo w e d t o d ry on
a paper to w e l.
A t tim e o f f r u i t d e h is c e n c e , seeds and pod were sepa r­
a te d , p la c e d in s e p a ra te w e ig h in g b o t t le s , , and weighed im m e d ia te ly .
Seeds and pods were oven d r ie d 24 hours a t IOO0C, co o le d in a d e s s ic a to r
f o r 3 h o u rs , and w e igh ed.
34
F o r t y - f o u r in d iv id u a l brown pods were sam pled.
Means, sta n d a rd
d e v ia t io n s , and sta n d a rd e r r o r s were, c a lc u la te d based on w e ig h ts and
m o is tu re p e rce n ta g e o f f r u i t ,
seeds, and pod.
R e s u lts and D is c u s s io n
E v a lu a tio n o f Clones f o r M o is tu re
Percentage a t Dehiscence
B ir d s fo o t t r e f o i l c lo n e s d id n o t d i f f e r in m o is tu re percen tag e o f
brown f r u i t a t d eh iscen ce (T a b le 7 ) , b u t d if f e r e d in m o is tu re percen tag e
o f f r u i t a t h a rv e s t (T a b le 8 ) due t o d iffe r e n c e s in m a t u r it y .
Mean
m o is tu re p e rce n ta g e o f a i r - d r ie d f r u i t a t d eh iscen ce was 2 .5 0 + 0 .2 8 .
The mean m o is tu re p e rce n ta g e o f a i r - d r ie d f r u i t a t h a rv e s t was
7.6 9 + 0 .2 7 .
Based on th e s e d a ta i t appears t h a t seed p ro d u ce rs can use
a c r i t i c a l m o is tu re le v e l f o r f r u i t deh isce n ce o f b ir d s f o o t t r e f o i l r e ­
g a rd le s s o f g e n e tic m a t e r ia l.
Rate o f d ry down was n o t d e te rm in e d ,
however i t s e f f e c t s and im p o rta n ce have been s u b s ta n tia te d by M e tc a lfe ,
e t a l.
(2 5 ).
.
R e la tio n s h ip o f F r u i t , Seed, and
Pod M o is tu re a t Dehiscence
Mean m o is tu re p e rce n ta g e o f brown f r u i t a t d eh iscen ce was 7.28 +
' 0 .2 0 , w ith a range o f 4 .1 8 - 10.00 p e r c e n t.
These d a ta suggest t h a t
. m is tin g sh o u ld b e g in when f r u i t m o is tu re is a p p ro x im a te ly 10 p e rc e n t.
S u n lig h t, r e l a t i v e h u m id ity , w in d , te m p e ra tu re , and c lo u d c o v e r can a l t e r
J
35
T able 7 .
Clone
Number
M o is tu re p e rce n ta g e ( a i r d r y b a s is ) o f f r u i t fro m f o u r clo n e s
o f b ir d s f o o t t r e f o i l a t deh isce n ce in 1980 a t Bozeman, MT.
I
,6
M o is tu re C o nte nt o f
F r u it a t Dehiscence
(%)
3.167
2
16
2.625
3
16
1.894
4
16
2.300
T able 8 .
Clone
Number
I
2 ..
3
4
Number o f
F r u it Sampled
M o is tu re p e rc e n ta g e .o f fr e s h f r u i t ( a i r d ry b a s is ) o f fo u r
c lo n e s o f b ir d s f o o t t r e f o i l when p la ce d in an e n viro n m e n ta l
chamber a t Bozeman, MT.
Number o f
Pods Samples
16
16
16
16
Mean M o is tu re Percentage
o f Fresh' F r u i t a t H a rve st
.8 .5 1 9
8.106
6.126
8 .0 2 6
a*
a
b
a
*Means in th e same row fo llo w e d by th e same l e t t e r a re n o t s ig n i f i c a n t l y d i f f e r e n t by Duncan's M u lt ip le Range T e st a t p = .05 le v e l.
36
th e dry-down, r a te o f f r u i t ( I , 2 , 4 , 4 9 ) .
T h e re fo r e ,fr e q u e n t f r u i t
sam01aigg is necessary t o d e te rm in e when m is tin g shou ld b e g in .
M o is tu re p e rce n ta g e o f f r u i t ,
r e la te d w ith each o th e r (T a b le 9 ) .
seed, and pod were s i g n i f i c a n t l y c o r
The c o r r e la t io n c o e f f ic ie n t f o r
m o is tu re p e rce n ta g e o f th e f r u i t and pod a t dehiscen ce was r = .8 8 ,
in d ic a t in g t h a t f r u i t m o is tu re can be used t o d e te rm in e when brown pods
w i l l d e h is c e in th e f i e l d
and when m is tin g should b e g in .
The means, s ta n d a rd d e v ia t io n s , and sta n d a rd e r r o r s f o r f r u i t ,
seed, and pod a t d e h iscen ce are.show n in T a b le 10. The seed co n ta in e d
more m o is tu re th a n th e pod and f r u i t .
P re vio u s work (C h a p te r I )
in d ic a te s t h a t m is tin g b ir d s f o o t t r e f o i l
tw ic e d a i ly in c re a s e d seed p r o d u c tio n .
T h is stu d y in d ic a te s t h a t seed
p ro d u ce rs shou ld b e g in m is tin g b e fo re m o is tu re c o n te n t o f f r u i t reaches
10 p e rc e n t.
I f e n v iro n m e n ta l c o n d itio n s a re such t h a t pod .d e h isce n ce
w i l l o c c u r, th e fre q u e n c y o f m is tin g is dependent upon th e s p e c if ic
e n v iro n m e n ta l c o n d it io n s .
Under h o t, d r y (lo w r e la t iv e h u m id ity ) con­
d i t i o n s , m is tin g must o c c u r more f r e q u e n t ly th a n under c o o l and wet
c o n d it io n s .
37
T able 9 .
C o r r e la tio n m a tr ix showing th e r e la t io n s h ip o f m o is tu re
p e rce n ta g e o f pod, seed, and f r u i t a t d e h isce n ce .
• P e rce n t
M o is tu re o f :
Pods a t
S h a tte r
Pods a t s h a t t e r
-r
Seeds a t s h a t t e r
0 .4 7 *
F r u it a t s h a t t e r
0 .8 8 * *
Seeds a t
S h a tte r
F r u it a t
S h a tte r
0 .7 9 * *
* , * * C o e f f i c ie n ts were s ig n i f i c a n t a t th e .05 and .01 le v e l o f
p r o b a b il it y , r e s p e c t iv e ly .
T ab le 10.
Means, s ta n d a rd d e v ia t io n s , and sta n d a rd e r r o r s o f th e p e r
c e n t m o is tu re o f pods, seeds, and f r u i t a t d e h is c e n c e .
Pods
6.1 9
1.47
0.22
Seeds
8 .7 5 .
1 .81
0.2 7
F r u it
7.2 8
1.67
0.20
I
LU
S
CO
X
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40
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MONTANA STATE UNIVERSITY LIBRARIES
stks N378. H8747©Theses
The effects of misting upon seed yield o
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