Variability studies on leafy spurge (Euphorbia esula L.)
by Duane Randall Arneklev
A thesis submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE
in Agronomy
Montana State University
© Copyright by Duane Randall Arneklev (1963)
Abstract:
Root sections of leafy spurge, Euphorbia esula, were collected from nine locations in the United States
and Canada and grown in the greenhouse at Bozeman, Montana. Material from each location was
referred" to as a strain. Differences between strains were noted in leaf size and shape and in root
characteristics. All plants appeared to fit the botanical description for Euphorbia esula, with the
possible exception of the Canadian strain which may be a E.esula X Ehcy-parissias cross. When all
strains were treated With -2,4-D amine at 0.25, 0.5 and 1.0 pound per acre rates, and evaluated by
visual means, different strains appeared to exhibit varying levels of tolerance to this herbicide. As the
rate per acre of 2,4-D was increased, differential results were not. as pronounced. Gibberellic acid’
stimulated the growth of all strains when applied both as a soil and as a foliage treatment. Those strains
most susceptible to 2,4-D applications appeared to also be most responsive to growth stimulation by
gibberellic acid. When gibberellic acid was used as a pretreatment' to 2,4-D appli cations, no apparent
advantage was realized. In studies of leaf characteristics little difference was found in the cuticle
thickness between strains. Stomata numbers varied both within and between strains. Neither the cuticle
thickness or the number of stomata appeared to be important in the 2,4-D response obtained. By
lengthening the photoperiod and subjecting the semi-dormant plants to periods of cold temperatures,
increased growth was observed.
VARIABILITY STUDIES GE LEAFY' SPURGE
CE u p h b r b ia e s u l a -L* ■)
by
DUADE RANDALL ARDEKLEV
■ v •
A t h e s i s s u b m i t te d in- p a r t i a l " f u l f i l l m e n t
o f t h e r e q u i r e m e n ts f o r t h e d e g re e
of
MASTER OF SCIENCE
in
Agronom y
A p p ro v e d :
H e a d ^ M a jo r D e p a rtm e n t
E xam ining, C o m m itte e
D ban 5 G r a d u a t e D i v i s i o n
MODTADA" STATE COLLEGE
' Bozem an 5 M ontana
M arch 5 1963
iii
ACKNOWLEDGMENT
The a u t h o r w is h e s t o t h a n k L a u re n c e 0 . B a k e r f o r h i s m any h e l p f u l
s u g g e s t i o n s a n d e n c o u ra g e m e n t th r o u g h o u t t h i s work*
A p p re c ia tio n i s
a l s o e x p r e s s e d f o r t h e c o n t r i b u t i o n s o f D r . K. H. H a r r i s o n i n s l i d e
p r e p a r a t i o n a n d s t a i n i n g p r o c e d u r e , t o D r. J . R. S c h a e f f e r f o r c y to l o g i c a l a n d p h o t o g r a p h i c t e c h n i q u e s , t o F r a n k T h r a s h e r f o r t h e chrom o­
some p h o to m ic r o g r a p h o f C anada t h i s t l e
i n m aking t h i s w ork p o s s i b l e .
an d t o t h e o t h e r s who h e lp e d
TABLE OF 'CONTENTS
P age
' ACKNOWLEDGMENT. .....................................................
. . .
iii
LIST OF TABLES.
LIST OF APPENDIX TABLES . . . . . . . . . . .
i- . . .
vi
LIST OF FIGURES ...............................................................
. . . .
-v ii
ABSTRACT. . . . . . .
INTRODUCTION.
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REVIEW OF LITERATURE. . . . . . . . . . . . . . . . .
H is to r y o f P l a n t I n tr o d u c tio n and D i s t r i b u t i o n .
C y to lo g ic a l I n v e s t i g a t i o n s . .
. " . "I . -. . . .
D i f f e r e n c e s i n P h y s i o l o g i c a l ' R e sp o n se . » . . .
D i f f e r e n c e s in 'M o r p h o lo g y . i
i . .
D orm ancy. . . .
. . . . o . . . . . . . . . . .
MATERIALS AND METHODS
C y to lo g ic a l P ro c e d u re s . . . *
*
*
D i f f e r e n c e s i n P h y s i o l o g i c a l R e sp o n se
D i f f e r e n c e s i n M o rp h o lo g y
D orm ancy.
O
RESULTS
0
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O
O
O
O
O
O
O
O
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O
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Qytological
D ifferences
Differences
Dormancy. .
DISCUSSION.
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APPENDIX.
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Findings. . .. . -. . . . . . . . . ■. ■.
in Physib Iogi c a l‘Response . . . . . . ..
in Morphology
^
.
. . . . . . . * . . . . * &@
. . . . O
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SUMMARY O O 6 O- Q O O ' O O O O O D- '6 O O . . .
LITERATURE CITED.
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3It
LIST OF TABLES
TABLE
I.
The r e l a t i v e ‘t o l e r a n c e o f n i n e ' s t r a i n s ' o f l e a f y
s p u rg e t o 2 5 U-D a s e v a l u a t e d b y v i s u a l m e a n s . '
TABLE I I .
•'C u tic le t h i c k n e s s m e a s u re d in " 'm ic r o n s oh l e a f
s u r f a c e s on n i n e s t r a i n s o f l e a f y s p u r g e .
TABLE H I .
A v e ra g e num ber o f s to m a ta c o u n te d ' on t h e u p p e r
and lo w e r l e a f s u r f a c e s o f n i n e l e a f y s p u rg e
1s t r a i n s . '
LIST OF APPENDIX TABLES
TABLE
I,
TABLE
II.
I n d i v i d u a l '- r a t i n g s on n i n e s t r a i n s o f l e a f y
' s p u rg e t r e a t e d w i t h t h r e e r a t e s o f EjlIi-D .
T h e ’w e ig h t b e f o r e arid a f t e r t r e a t m e n t and t h e
p e r c e n t a g e ' c h an g e i n w e ig h t' o f l e a f y s p u r g e '
s h o o ts t r e a t e d w i t h t w o ‘0 .2 5 l b / a c r e r a t e s o f
2 , L-D.
TABLE I I I ,
The ra w d a t a f o r u p p e r and lo w e r s to m a ta c o u n ts
on l e a f y s p u r g e s t r a i n s .
TABLE
A n a l y s is o f v a r i a n c e f o r s to m a ta d i s t r i b u t i o n
on l e a f s u r f a c e s o f n i n e s t r a i n s o f l e a f y s p u rg e
IV .
LIST OF FIGURES
P age
F ig u re
F ig u r e
F ig u re
F ig u re
F ig u r e
F ig u re
F ig u re
F ig u re
F ig u r e
I.
2o
3,
U,
3«
6»
7.
8.
9.
F ig u r e 1 0 .
Two d i f f e r e n t s t r a i n s o f l e a f y s p u r g e . The e i g h t
i n c h 's h o o ts '- a b o v e " r e p r e s e n t" t h e C a n a d ia n and t h e
U o r th D a k o ta s e l e c t i o n s , B elow a r e t h e l e a f
s h a p e s fro m t h e ' t o p ^ m i d - s e c t i o n a n d b a s a l p o r ­
t i o n o f t h e s h o o ts f o r e a c h s t r a i n ,
23
P h o to m ic ro g r a p h s o f C i r s i u i ir a r v e n s e ,, 2n-3lt<,
( a b o v e ) a h d ' E u p K o rb ia ’ e s u l a ,, 2 n -6 0 (b e lo w ) j
sh o w in g r e l a t i v e s i z e s o f t h e chrom osom es.
23
The a v e r a g e i n c r e a s e i n w e i g h t “o f t o p g ro w th fro m
n in e l e a f y sp u rg e s t r a i n s e x p re s s e d as a p e rc e n t'
o f t h e c h e c k 1|5 d a y s a f t e r t r e a t i n g w i t h G5U-Do
28
The a v e r a g e "sh o o t" grow th- of" "two r e l a t i v e l y r e s i s ­
t a n t ' s t r a i n s ‘~’b f '’l e a f y ’s p u r g e a f t e r 2 5U”D t r e a t - Iiient 5 com pared w i t h u n t r e a t e d c h e c k s .
30
The a v e r a g e s h o o t grow th" o f two" r e l a t i v e l y s u s ­
c e p t i b l e " " s 'tra ln s " a f t e r 2 5U-D t r e a t m e n t 5 co m p ared
w ith u n tre a te d c h e ck s.
30
A v e ra g e ' r o o t g ro w th o f f o u r " v i s u a l l y r a t e d
s t r a i n s , tw o r e l a t i v e l y s u s c e p t i b l e (M . 1 I a n d •
OAU) And""two" r e l a t i v e l y r e s i s t a n t "("MiUEII"and
UD" I ) , " t r e a t e d w i t h 2 , U-D a t a r a t e o f 0 ,3
Ib /a c re .
31
The p l a n t " bn" t h e l e f t ' s i d e o f t h e b o x was t r e a t e d
w i t h 0 ,3 I b / a c f e o f G5U-D, The p l a n t on t h e
rig h t i s a check,
33
The " t a l l e r 'p l a n t " " 6 n " t h e ’’l e f t " s id e ’ was sp ra y e d "
w i t h a 1000 ppm s o l u t i o n o f g i b b e r e l l i 'c a c i d a t a
r a t e p f “"80 g a l / a c r e . The p l a n t on t h e r i g h t s i d e
i s a check p l a n t .
33
N ine s t r a i n s a n d t h e i r r e l a t i v e g ro w th r e s p o n s e
t o 3 0 ' m l o f a 100 ppm s o l u t i o n o f g i b b e r e l l i c
a c id a p p lie d as a s o i l tre a tm e n t „
3U
Two r e l a t i v e l y s u s c e p t i b l e p l a n t s (iCX)L a n d 'CAN)
a n d tw o r e l a t i v e l y "r e s i s t a n t p l a n t s (ND I an d
S.DV) e x h i b i t d i f f e r e n t l e v e l s o f r e s p o n s e when
t r e a t e d w i t h g i b b e r e l l i c a c i d . The c h e c k s a r e
u n t r e a t e d and r e p r e s e n t n o rm a l g ro w th .
3U
v iii
P age
F ig u re 1 1 ,
F ig u re 1 2 ,
F i g u r e 13«
F i g u r e lU ,
The i n c r e a s e d s h o o t g ro w th o f t w o . s t r a i n s o f
l e a i y s p u r g e when t r e a t e d w i t h f o l i a r a p p l i ­
c a tio n s o f g i b b e r e ll ic a c id .
35
A c r o s s " s e c t i o n o f "a' l e a f y s p u r g e l e a f , n o t e
t h e t h i c k e r c u t i c l e on t h e u n d e r s i d e o f t h e
l e a f ra id -rib .
39
The r o o t s y s te m s o f t h r e e d i f f e r e n t s t r a i n s o f
l e a f y s p u rg e w hich" w ere t a k e n fro m 18 i n c h d e e p
g re e n h o u s e c a n s an d w a s h e d .
39
A v e ra g e num ber o f " s t o m a t a bn t h e u p p e r and
lo w e r " le a f s u r f a c e s o f n in e s t r a i n s o f le a f y
sp u rg e .
k2
ABSTRACT
R o o t s e c t i o n s o f l e a f y .s p u rg e . E u p h o r b ia G s u la il w ere c o l l e c t e d
fro m n i n e " 'l b c a t i o n s i n t h e U n ite d S t a t e s a n d C an ad a and' grow n i n t h e
g re e n h o u s e a t Bozem ah 5 M o n ta n a . M a t e r i a l "from e a c h 'l o c a t i o n was
r e f e r r e d " t o a s a ' s t r a i n . ' " D if f e r e n c e s " b e t w e e n " s t r a i n s w e re n o te d i n
l e a f s i z e an d s h a p e a n d i n r o o t c h a r a c t e r i s t i c s '. " A l l p l a n t s a p p e a re d
t o f i t t h e b o t a n i c a l d e s c r i p t i o n f o r E u p h o r b ia e s u l a , " w ith t h e p o s s i ­
b l e e x c e p t i o n o f t h e 'C a n a d i a n " s t r a i h 'w h i c h may b e a E 0 'e s u l a X E h c y p a r i s s i a s c r o s s . When a l l s t r a i n s w e re t r e a t e d w i^ h r'2 5ii-I) ,am in e a t '
0 . 2^5 0 .5 a n d 1 .0 p o u n d per" a c r e r a t e s 5""an d ""ev alu ated b y v i s u a l m ean s 5
d i f f e r e n t s t r a i n s ap p e are d to e x h ib i t v a ry in g l e v e ls o f to le r a n c e to
t h i s h e rb ic id e .
As t h e r a t e p e r a c r e o f 2 5Ii-D was i n c r e a s e d , d i f f e r ­
e n t i a l r e s u l t s w e re n o t. a s pronounced"^
G ib b e r e llic a c id ' s tim u la te d
t h e g ro w th o f a l l s t r a i n s when a p p l i e d b o th a s a s o i l a n d a s a f o l i a g e
t r e a t m e n t o T h o se s t r a i n s m ost s u s c e p t i b l e "t o 2 , Ii-D a p p l i c a t i o n s a p ­
p e a r e d t o " a ls o b e m o s t " r e s p o n s iv e t o g ro w th ' s t i m u l a t i o n b y g i b b e r e l l i c
a c i d . # i e n g i b b e r e l l i c a c i d was u s e d a s a p r e tr e a tm e n t" t o 2 ,U-D a p p l i
c a t i o n s , no a p p a r e n t a d v a n ta g e was r e a l i z e d .
In s tu d ie s o f le a f
c h a r a c t e r i s t i c s l i t t l e d i f f e r e n c e was f o u n d i n t h e c u t i c l e t h i c k n e s s
b e tw e e n s t r a i n s . " S to m a ta num bers " v a r i e d b o th " w i t h i n and b e tw e e n
s tra in s .
N e i t h e r t h e c u t i c l e th ic k n e s s " o r t h e num ber o f s to m a ta
a p p e a r e d t o b e i m p o r t a n t i n t h e 2 , Ii-D r e s p o n s e o b t a i n e d . B y l e n g t h e n ­
i n g t h e p h o t o p e r i o d an d s u b j e c t i n g t h e s e m i-d o rm a n t p l a n t s t o p e r i o d s
o f c o ld t e m p e r a t u r e s , i n c r e a s e d g ro w th was o b s e r v e d .
INTRODUCTION
New m eth o d s f o r o b t a i n i n g b e t t e r w eed c o n t r o l a r e c o n s t a n t l y b e in g
e x p lo re d .
The u s e o f h e r b i c i d e s t o
c o n t r o l w eedy s p e c i e s h a s b e e n o f
g r e a t v a l u e an d p r o m is e s e v e n g r e a t e r b e n e f i t s f o r t h e f u t u r e .
Howevery
e v e n w i t h t h i s p r o g r e s s m any p ro b le m s r e m a in t o b e s o l v e d .
Some o f t h e m o st v e x in g p ro b le m s i n p e r e n n i a l w eed c o n t r o l a r e t h e
e r r a t i c r e s u l t s r e p o r t e d b y v a r i o u s i n v e s t i g a t o r s on a g iv e n w eed
s p e c ie s .
Some o f t h e s e v a r i a t i o n s c a n b e e x p l a i n e d b y d i f f e r e n c e s i n
s o i l a n d o t h e r e n v ir o n m e n t a l c o n d i t i o n s , o t h e r s c a n n o t.
I n g e n e ra l,
v a r i a b i l i t y w i t h i n a p a r t i c u l a r p l a n t s p e c i e s h a s n o t b e e n f u l l y e v a lu ­
a t e d an d c o n s e q u e n t l y , i t i s p o o r l y u n d e r s t o o d .
.
I
L e a f y s p u rg e i s
c u lt to
-
,
a v e r y p e r s i s t e n t w eed an d one o f t h e m o st d i f f i ­
c o n t r o l w i t h e i t h e r c u l t u r a l o r c h e m ic a l m ea n s.
I t i s s p re a d in g
r a p i d l y a n d when e s t a b l i s h e d , s e v e r e l y r e d u c e s t h e y i e l d o f d e s i r a b l e
p la n ts .
T r e a tm e n ts t h a t a r e r e p o r t e d t o b e e f f e c t i v e i n one a r e a a r e
n o t a lw a y s e f f e c t i v e i n o t h e r 'a r e a s „■ V a r i a b i l i t y i n t h e s p e c i e s h a s
b e e n s u g g e s te d t o e x p la in d i f f e r e n t r e s u l t s .
I n th is s tu d y ro o t se c ­
t i o n s w ere c o l l e c t e d fro m v a r i o u s l o c a t i o n s , p r o p a g a t e d a n d t e s t e d a t
Bozeman t o d e te r m in e w h e th e r t h i s s p e c i e s e x h i b i t s I n h e r e n t p h y s io ­
lo g ic a l d iffe re n c e s .
REVIEW OF LITERATURE
H i s t o r y of. P l a n t I n t r o d u c t i o n an d D i s t r i b u t i o n
L i t t l e i s known o f t h e d a t e o r m eth o d b y w h ic h l e a f y s p u r g e was
A c c o rd in g t o Bakke ( 3 ) 5 H egi
f i r s t i n t r o d u c e d i n t o t h e New "World ( 3 U ) .
(2 3 ) r e p o r t e d t h a t t h i s p l a n t was r e c o g n i z e d i n E u ro p e a s e a r l y as
1000 A.Do a n d was known a s w o l f ’s m i l k .
The m i l k - l i k e l a t e x was con­
s id e r e d t o have m e d ic in a l p r o p e r t i e s .
A c c o r d in g t o H an so n and Rudd ( 2 2 ) , B r i t t o n ( 7 ) r e p o r t e d t h a t t h e
e a r l i e s t N o rth A m e ric a n s p e c im e n o f l e a f y s p u rg e was c o l l e c t e d b y W illia m
O akes a t N ew bury, M a s s a c h u s e t t s , i n 1 8 2 7 .
A sa G ra y r e c o g n i z e d t h i s p l a n t
i n t h e f i r s t e d i t i o n o f h i s M a n u a l, p u b l i s h e d i n 181*8.
t h i s w eed w o u ld l i k e l y becom e tr o u b l e s o m e .
B a th o
(U)
He i n d i c a t e d t h a t
re p o rte d th a t seed
was i n t r o d u c e d i n t o S o u th w e s te r n M in n e s o ta i n a b u s h e l o f o a t s b r o u g h t
fro m R u s s i a i n 1 8 9 0 .
A c o l l e c t i o n made a t Mount P l e a s a n t , Io w a , i n 1899
r e p r e s e n t e d t h e f i r s t a u t h e n t i c r e c o r d o f t h i s w eed i n t h a t s t a t e
I t h a s b e e n known t o e x i s t i n N o rth D a k o ta s i n c e 1909 ( 2 2 ) .
(3) .
I n C a li­
f o r n i a i n f e s t a t i o n s w e re a l s o i d e n t i f i e d a s e a r l y as 1916 , a c c o r d in g t o
B e llu e ( 3 ) .
B la n k e n s h ip ( 6 ) w r i t i n g i n 1901 d o e s n o t m e n tio n l e a f y s p u rg e a s a
w eed p ro b le m i n M o n ta n a .
-Nor i s i t m e n tio n e d b y S w in g le e t a l .
1920 a s b e i n g among t h e " F i f t y I m p o r ta n t W eeds o f M o n ta n a " .
M o n tan a s p e c im e n on f i l e
(UU)
in
The f i r s t
i n t h e H e rb a riu m a t" M is s o u l a was c o l l e c t e d i n
1923 fro m M is s o u la C o u n ty .
I n 192U a s p e c im e n was c o l l e c t e d i n P a rk
C o u n ty and p l a c e d i n t h e H e rb a riu m a t B ozem an.
H e ik e s (2U) r e p o r t e d t h e
-3r e s i i l t s o f a w eed s u r v e y made b y e x t e n s i o n a g e n ts i n 19!?!?.
I t l i s t s th e
a c r e a g e o f l e a f y s p u r g e t o b e a b o u t I T sOOO an d t h a t a lo n g # t h R u s s ia n
kn ap w eed , i t w as t h e m o st r a p i d l y s p r e a d i n g p e r e n n i a l w eed i n t h e s t a t e .
T h is w eed was n o t r e c o g n i z e d i n w e s t e r n C an ad a u n t i l t h e e a r l y p a r t
o f yt h e . 2 0 t h c e n t u r y ( U l) .
A l o c a l c o l l e c t o r i n G r e e n s t r e e t , S a s k a tc h e ­
w an , a t t r i b u t e d t h e i n t r o d u c t i o n o f l e a f y s p u r g e i n t h a t a r e a t o g r a s s
s a m p le s o b t a i n e d i n 1912 fro m s e e d g ro w e rs i n E n g la n d (3U)<.
Many m ore
i n f e s t a t i o n s h a v e p r o b a b l y b e e n i n t r o d u c e d i n a s i m i l a r m a n n e r.
T h is p l a n t ' s
a b i l i t y t o w i t h s t a n d a d v e r s e c o n d i t i o n s , co m b in ed w i t h
good s e e d p r o d u c t i o n c a p a b i l i t i e s and a m ark ed c a p a c i t y f o r v e g e t a t i v e
r e p r o d u c tio n , h a s c o n tr ib u te d to i t s p e r s i s t e n c e and c o n ti n u a l s p re a d .
B o th t h e s e e d and r o o t s a r e c o n s i d e r e d t o b e i m p o r ta n t i n t h e d i s s e m in a ­
tio n o f th is p la n t.
M a tu re p l a n t s o f l e a f y s p u r g e h a v e t h e c a p a c i t y to
d e h i s c e s e e d s i n a n e x p l o s i v e m anner fro m d r y c a p s u l e s up t o 13 f e e t
fro m t h e p a r e n t p l a n t ( 3 ) .
-*■
T h is f e a t u r e a lo n e c o u ld a c c o u n t f o r a f a i r ­
l y r a p id s p re a d o f p a tc h e s o f t h i s w eed.
S e lle c k e t a l .
(U l) r io te d t h a t
o v e r a s e v e n y e a r p e r i o d , l e a f y s p u r g e was a b l e t o s p r e a d v e g e t a t i v e I y
e v e r y y e a r i n c o m p e t it io n w i t h a l l o t h e r s p e c i e s i n t h e i r C a n a d ia n s t u d y
a re a s.
The p e r i m e t e r o f e s t a b l i s h e d p a t c h e s u s u a l l y i n c r e a s e d fro m I t o
3 f e e t p e r y e a r , and o c c a s i o n a l l y a s much a s 11 f e e t .
'
I t h a s b e e n r e p o r t e d ( 2 0 , 22) t h a t l e a f y s p u rg e now h a s i n f e s t e d
n e a r l y e v e r y p r o v in c e i n C anada and m tist o f t h e s t a t e s i n t h e n o r t h e r n
h a l f o f t h e U n ite d S t a t e s .
I t is
c o n s i d e r e d a w eed o f s e r i o u s p r o p o r t i o n s i n w e s t e r n C a n a d a ,
an d h a s a c h ie v e d w i d e - s p r e a d d i s t r i b u t i o n i n t h a t c o u n tr y , a c c o r d in g t o
=Ij.=
M oore ( J l t ) 0
S e lIe c k e t a l„
( I t l ) s t a t e d t h a t 'a b o u t 1 0 ,0 0 0 a c r e s w ere
m apped i n S a s k a tc h e w a n a l o n e , a n d t h a t t h e i n f e s t e d a c r e a g e i n (Canada
w o u ld l i k e l y a p p ro a c h 3 J ,0 0 0 t o ltO,0OO a c r e s 0
The c o n t i n u a l s p r e a d o f
t h i s weed i n b o t h t h e U n ite d S t a t e s and i n C an ad a i n d i c a t e s t h a t t h e
p r e s e n t m eth o d s o f c o n t r p l u n d e r m o st c o n d i t i o n s a r e i n e f f e c t i v e «
C y to Io g ic a l I n v e s tig a tio n s
I n E u r a s i a , E u p h o rb ia , e s u l a i s w i d e l y d i s t r i b u t e d , b u t i s n o t c o n ­
s i d e r e d t o b e a p a r t i c u l a r l y u n d e s i r a b l e w eed ( h i ) „
P o p u la tio n s o f t h i s
w eed i n E u ro p e a p p e a r t o b e h i g h l y v a r i a b l e an d some a u t h o r s q u e s t i o n
w h e th e r t h e s p e c i e s r e p r e s e n t e d on t h e tw o c o n t i n e n t s a r e t h e sam e ( 21 )„
Much c o n f u s io n a n d d is a g r e e m e n t h a s a r i s e n o v e r t h e ta x o n o m ic c l a s s i f i ­
c a t i o n o f E u p h o r b ia b e c a u s e o f h y b r i d i z i n g b e tw e e n s p e c i e s w i t h i n t h e
genus ( h i ) „
N a t u r a l h y b r i d s b e tw e e n E u p h o r b ia v i r g a t a a n d E . e s u l a a n d
Eo- l u c l d a Wo & Ko h a v e b e e n r e p o r t e d ( 2 3 ) o
le a f c h a ra c te r is tic s a re
u s e d b y s e v e r a l i n v e s t i g a t o r s t o d i f f e r e n t i a t e b e tw e e n c l o s e l y r e l a t e d
s p e c ie s (2 3 , 1 9 , 3 6 )0
T he r e l a t i v e w i d t h o f t h e a p i c a l a n d b a s a l p o r ­
t i o n s o f t h e l e a f a p p e a r t o b e m ost f r e q u e n t l y u s e d t o d i s t i n g u i s h E 9
v i r g a t a a n d Eo e s u l a .
Groh (1 9 ) r e p o r t e d t h a t t h e l e a v e s o f E 0 v i r g a t a
a r e b r o a d e s t b e lo w t h e m id d le , w h ile E 9 e s u l a h a s t h e b r o a d e s t p a r t o f
t h e l e a f ab o v e t h e m id d le *
W h ile t h e l e a v e s o f E . I u c i d a a r e b r o a d e r
t h a n t h e o t h e r two s p e c i e s , n o t a l l i n v e s t i g a t o r s a g r e e t h a t l e a f w id th
i s a d i s t i n g u i s h i n g e n o u g h c h a r a c t e r i s t i c t o s e p a r a t e Eo- e s u l a and E 9
v i r g a t a b e c a u s e o f so much v a r i a b i l i t y b e tw e e n p l a n t s d u e t o e d a p h ic and,
e n v ir o n m e n ta l c o n d i t i o n s „
M oore ( J lt) i n d i c a t e d t h a t t h e i n t r e g r e s s i o n o f t h e ab o v e s p e c i e s
may b e r e s p o n s i b l e f o r much o f t h e v a r i a t i o n n o te d i n t h e p o p u l a t i o n o f
E» e s u l a .
He fo u n d g r e a t v a r i a b i l i t y i n t h e p l a n t s t h a t he e x a m in e d i n
C anada 5 b u t c o n c lu d e d t h a t a l l N b r th A m e ric an c o l l e c t i o n s h e h a d s e e n
s h o u ld b e c l a s s e d a s E . , e s u l a Lo,
Some s p e c im e n s p o s s e s s e d c h a r a c t e r i s ­
t i c s t h a t a p p ro a c h e d E t.1, V i r g a t a 5 so t h e p o s s i b i l i t y t h a t h y b r id s o f
E- e s u l a a n d E^- v i r g a t a - m ig h t o c c u r was n o t e x c lu d e d .
He a l s o e x p r e s s e d
t h e o p i n i o n t h a t t h e d i f f e r e n c e b e tw e e n t h e s e tw o s p e c i e s was so l i t t l e
t h a t p o s s i b l y a l l p l a n t s s h o u ld b e c l a s s e d a s o n e s p e c i e s . P r i t c h a r d ( 3 9 ) a l s o n o t e d t h a t E u p h o r b ia . C y p a r i s s i a s 5 i n t h e t e t r a p l o i d c o n d i t i o n (Pn=ItO ) 5 w i l l i n t e r b r e e d f r e e l y w i t h E.' e g u l a (Pty=SO) 5
g i v i n g a (Pn=^O ) c o n d i t i o n .
The l e a v e s o f 'E . c y p a r i s s i a s a r e n a rr o w e r
\
th a n th e o th e r s p e c ie s .
I t beco m es a p p a r e n t " t h a t a n e x t e n s i v e s u r v e y o f t h e chrom osom e num­
b e r s o f t h e V e s u la com plex " 5 w o u ld b e d e s i r a b l e i n u n d e r s t a n d i n g t h e
m o rp h o lo g y an d g e n e t i c m akeup o f t h e p l a n t s fo u n d on t h i s c o n t i n e n t an d
i n E u ro p e.
-C o n s id e rin g t h e e c o n o m ic im p o r ta n c e o f t h e E u p h q r b y a c e a e 5
P e r r y (3 8 ) s t a t e d t h a t i t was r e m a r k a b le t h a t so. l i t t l e
b e e n p a id to t h i s
g ro u p c y t o l o g i c a l l y .
a t t e n t i o n had
He l i s t e d t h e f o l l o w i n g r e a s o n s
why h e f e l t t h i s f a m i l y was u n a t t r a c t i v e f o r 'c y fc o lo g ic a l s t u d y ;
chrom o­
some num bers a r e e x tr e m e l y V a r i a b l e 5 f i x a t i o n o f m a t e r i a l i s d i f f i c u l t
and t h e chrom osqm es a r e s m a l l i n s i z e .
P e r r y (3 8 ) S d d e d 5 h o w e v e r 5 t h a t ',
e x a c t ta x o n o m ic k n o w le d g e m u st b e o b t a i n e d on w eeds b e f o r e o t h e r •
s t u d i e s o f v i t a l im p o r ta n c e c a n b e d e a l t w i t h i n t e l l i g e n t l y .
An u n d e r s t a n d i n g o f t h e germ p la s m i s i m p o r ta n t f o r t h e s a k e o f r e ­
i n f o r c i n g ta x o n o m ic i n v e s t i g a t i o n s 5 i n s u p p ly i n g a d d i t i o n a l i n f o r m a t i o n
x.
-6on t h e v a r i a b i l i t y o r s t a b i l i t y o f d i f f e r e n t w eeds a n d i t
c o u ld ^ ls o
s h e d a d d i t i o n a l i n s i g h t on t h e p o s s i b l e r e l a t i o n s h i p o f p l o i d y t o a g ­
g r e s s i v e n e s s 5 l i f e d u r a t i o n an d p l a n t h a b i t a t ( 3 7 ) .
p lo ts o f f e r t i l e
d i p l o i d (2n=2Q ) and t e t r a p l o i d
When e x p e r i m e n t a l
(2n=U0) p l a n t s o f E ,
c y p a r i s s i a s w ere c o m p a re d , P r i t c h a r d ( 3 9 ) n o te d t h a t t e t r a p l o i d s e x ­
h i b i t e d s t r o n g e r v e g e t a t i v e r e p r o d u c t i o n a n d t h a t p o l y p l o i d y was p r o b a ­
b l y c o n n e c te d w i t h t h e s p r e a d o f t h i s w e e d .
O th e r s t u d i e s on th e s i g ­
n i f i c a n c e o f p o l y p l o i d c o m p le x es a r e som ew hat c o n f l i c t i n g .
P e r r y (3 8 )
g i v e s a ^more d e t a i l e d d i s c u s s i o n on t h e s i g n i f i c a n c e o f p o l y p l o i d y .
D i f f e r e n c e s i n P h y s i o l o g i c a l R e sp o n se
V a r i a b i l i t y W ith in W eedy S p e c ie s
S e v e r a l r e s e a r c h w o rk e rs i n r e c e n t y e a r s h a v e b e e n a b le t o demon­
s t r a t e t h a t p l a n t s w i t h i n a g iv e n s p e c i e s w i l l re s p o n d w i t h v a r y in g
d e g r e e s o f r e s i s t a n c e w hen t r e a t e d w i t h a g i v e n r a t e o f h e r b i c i d e .
t e n s i v e t e s t s w ere c a r r i e d o u t b y W h itw o rth e t a l .
(£ 0 ) on f i e l d b i n d ­
w eed ( C o n v o lv u lu s a r v e n s i s L . )- t o d e te r m in e w h e th e r t h i s
show d i f f e r e n t i a l t o l e r a n c e t o 2 ,Ii-D'51".
Ex­
s p e c i e s w ould
T h e y c o l l e c t e d f i p l d b in d w e e d
s e e d s a m p le s fro m a num ber o f s t a t e s an d l o c a t i o n s ' and v e g e t a t i v e I y
p ro p a g a te d th e s e p l a n t s f o r h e r b ic id e t r e a tm e n ts .
When t r e a t e d w ith
2 , U-D a t a r a t e e q u i v a l e n t t o o n e - h a l f p o u n d p e r a c r e , p l a n t s e x h i b i t e d
a w id e r a n g e o f d i f f e r e n t i a l t o l e r a n c e t o t h e h e r b i c i d e .
s t u d i e d t h e r e s p o n s e o f s e v e r a l e c o ty p e s o f C anada t h i s t l e
r' 2 ,l i~ d i c h lo r o p h e n o x y a c e ti c a c i d
H odgson (2 6 )
( C ir s iu m
-7 a r-v e n s e ) t o h e r b i c i d e s .
The num ber o f s h o o ts t h a t s u r v i v e d 12 m onths
a f t e r t r e a t m e n t , b a s e d on t h e c o n t r o l p l o t s , w as t h e c r i t e r i o n u s e d t o
d e te r m in e t h e p e r c e n t c o n t r o l o b t a i n e d .
H hen 10 e c o ty p e s w e re t r e a t e d
e a c h y e a r o v e r a tw o y e a r p e r i o d a t t h e e a r l y - b l o o m s t a g e o f g ro w th , a t
a r a t e o f l.f>
p o u n d s 2 , !+-D p e r a c r e , c o n t r o l r a n g e d fro m U t o £8 p e r ­
c e n t.
U pound
W ith a
p e r a c re r a t e o f a m itr o le a p p lie d each y e a r f o r
tw o y e a r s t h e c o n t r o l r a n g e d fro m 21 t o 89 p e r c e n t .
C lo n e s o f q u a c k g r a s s ( A g ro p y ro n r e p e n s ) w e re fo u n d t o e x p r e s s
v a r i a t i o n s i n s e n s i t i v i t y t o d a la p o n , a c c o r d in g t o B u c h h o ltz ( 8 ) .
Q u a c k g ra s s s h o o t s w ere d r i e d and w e ig h e d 1+2 d a y s a f t e r b e i n g t r e a t e d
w i t h d a la p o n .
The w e ig h t o f t h e s h o o t g ro w th o f t h e t r e a t e d c lo n e s
r a n g e d fro m 6
t o 71 p e r c e n t o f t h e i r r e s p e c t i v e c h e c k s .
c lo n e s c o l l e c t e d fro m t h e sam e
Some o f t h e
l o c a t io n v a r ie d i n s e n s i t i v i t y to d a la p ­
o n , b u t t h i s d id n o t h o ld tr u e i n a l l in s t a n c e s .
O th e r p h y s i o l o g i c a l d i f f e r e n c e s h a v e .b e e n n o te d a n d r e p o r t e d b y
some r e s e a r c h w o r k e r s .
S e lle c k e t a l .
(U l)
n o te d c o n s id e r a b le v a r i a t i o n
i n t h e p e r c e n t a g e g e r m i n a t io n o f l e a f y s p u r g e s e e d c o l l e c t e d fro m d i f ­
f e r e n t s o u r c e s , r a n g i n g b e tw e e n Uo2 and 3 8 .0 p e r c e n t ,
T hey f e l t t h a t
m o st p r o b a b l y t h i s v a r i a t i o n was due t o g e n e t i c d i f f e r e n c e s .
H ow ever,
t h e y d i d n o t r u l e o u t t h e p o s s i b i l i t y o f d o rm a n c y b e in g i n f l u e n c e d b y
e n v ir o n m e n t„
L e i g h t y ( 3 1 ) c a r r i e d o u t g e r m i n a t io n s t u d i e s on w i l d o a t s
and f o u n d t h a t s t r a i n s e x h i b i t e d d i f f e r e n t l e v e l s o f d o rm a n c y u p 't o
s e v e r a l m o n th s a f t e r h a r v e s t .
He f u r t h e r r e p o r t e d t h a t p r o g e n y i n m ost
c a s e s e x h i b i t e d a d e g r e e o f d o rm an cy s i m i l a r t o t h e p a r e n t .
K ru c k e b e rg
( 3 0 ) h a s shown g r e a t v a r i a b i l i t y among w i l d p l a n t s , p a r t i c u l a r l y i n
-8=
r e s p e c t to s e rp e n tin e s o i l s .
C la u s e n a n d H ie s e y (9). h a v e d e m o n s tr a te d
t h a t g e o g r a p h ic a n d a l t i t u d i n a l r a c e s do e x i s t w i t h i n s p e c i e s i n w i l d
p la n t p o p u la tio n s .
I t s h o u ld a l s o b e n o te d t h a t n o t a l l s t r a i n s o r e c o ty p e s c o l l e c t e d
e x h i b i t v a r y i n g r e s p o n s e s when t r e a t e d w i t h a. g iv e n h e r b i c i d e .
B aker
( 2 ) t r e a t e d 12 s t r a i n s o f w i l d o a t s w i t h a v a d e x a t s e v e r a l r a t e s an d ob­
s e r v e d no d i f f e r e n t i a l r e s p o n s e t o t h i s h e r b i c i d e .
S t u d i e s V i t h G row th R e g u l a t o r s
The mode o f a c t i o n o f 2 , L-D i s n o t e n t i r e l y u n d e r s t o o d ( 1 3 ) .
Sev­
e r a l i n v e s t i g a t o r s h a v e a tt e m p t e d t o l i n k t h e s e l e c t i v e a p t i p n o f 2 SL-D
t o d i f f e r e n t i a l a b s o r p t i o n , p e n e t r a t i o n and t r a n s l o c a t i o n .
H o l l y (2 7 )
u s e d u l t r a - v i o l e t d e t e c t i o n m eth o d s t o m e a s u re t h e am ount o f 2 , L-D w h ic h
p e n e tr a te d in to le a v e s o f v a rio u s s p e c ie s .
He fo u n d t h a t d i f f e r e n t i a l
p e n e t r a t i o n w as n o t a m a jo r f a c t o r i n g o v e r n in g s e l e c t i v i t y b e tw e e n
s p e c ie s .
W e in tra u b a n d h i s c o -w o rk e r s (L 9 ) u s e d
s t u d y i n g a b s o r p t i o n , and came t o
l a b e l l e d ' 2 , L- D i n
a s i m i l a r c o n c lu s io n .
The'' am ount o f
c h e m ic a l t h a t w o u ld t r a n s l o c a t e w i t h i n t h e p l a n t was fo u n d t o d i f f e r i n
th e s u s c e p t ib l e and r e s i s t a n t s p e c ie s .
In f a c t , b ro a d le a f p la n ts tra n s -,
l o c a t e d b e tw e e n f i v e and s e v e n t y t im e s g r e a t e r am ounts o f 2 , L-D t h a n
c e re a ls .
T h ey d i d e m p h a s iz e , h o w e v e r, t h a t t r a n s l o c a t i o n wp.s rio t t h e
o n ly f a c t o r in v o lv e d .
C r a f t s (I]?) s t a t e s t h a t , t s e l e c t i v i t y i s n o t d u e t o d i f f e r e n t i a l
w e t t i n g b u t t o p r o t o p l a s m i c t o l e r a n c e r e s u l t i n g fro m i n h e r e n t a b i l i t y o f
c e r t a i n p la n ts to r e s i s t th e to x ic a c tio n o f th e
tih e m ic a l . 11
A p p l i c a t io n s
o f 2 , L-D m u st r e a c h t h e l i v i n g t i s s u e o f p l a n t s t o b r i n g a b o u t i t s
to x ic
-9a c tio n .
T ra n s lo c a tio n o u t o f th e l e a f i s
g e n e r a l l y v i a t h e ph lo em and
m ovem ent fro m t h e r o o t o c c u r s i n t h e x y lem ( i t ? ) »
I n m e r is te m s ( 1 3 ) ,
" 2 , L-D d i s t u r b s t h e n o rm a l d i f f e r e n t i a t i o n o f t i s s u e b r i n g i n g a b o u t tum e r o u s g ro w th , d i s t o r t i o n o f t i s s u e s , a t y p i c fo rm s o f o r g a n s a n d , i f i n
h i g h eno u g h a m o u n ts , d e a t h " »
S w i t z e r and B ib b e y (L 5) i n d i c a t e t h a t i n t r e a t i n g l e a f y s p u rg e
2 , L-D o n l y p e n e t r a t e s t o t h e lo w e r s te m o r to t h e c ro w n , a n d t h e r e move­
m ent i s
checked.
T hey a l s o n o te d t h a t t h e d o m in an ce e x h i b i t e d b y one o r
tw o y o u n g s h o o t s , p r o h i b i t i n g o t h e r s h o o ts fro m d e v e lo p i n g , a p p e a r e d t o
b e im p o rta n t i n th e p e r s i s t e n c e o f t h i s w eed.
I t was s u g g e s t e d b y S h a f e r a n d M onson (L 2 ) t h a t g i b b e r e l l i h s c o u ld
p o s s i b l y b e u s e d t o a n a d v a n ta g e i n c o n j u n c t i o n w ith g ro w th r e g u l a ti n g m a te ria ls ,
th a t i t
T h e i r w ork w i t h g i b b e r e l l i c a c i d on l e a f y s p u r g e i n d i c a t e d
c o u ld b e u s e d s u c c e s s f u l l y i n b r e a k i n g d o rm a n c y a n d i n p ro m o tin g
g ro w th o f new a n d o l d b u d s’.
w ith p o ta s s iu m g i b b e r e l l a t e ,
H e lg e s o n (2 5 ) r e p o r t e d s i m i l a r f i n d i n g s
O th e r w ork b y A sh to n ( I ) s u g g e s t s t h a t
when g i b b e r e l l i c a c i d i s u s e d a s a p r e - t r e a t m e n t t o
2 , L-D a p p l i c a t i o n s ,
i n c r e a s e d t r a n s l o c a t i o n , o f t h e h e r b i c i d e w o u ld o c c u r ,
Ooulom be and
P a q u in ( 1 0 ) o b s e r v e d t h a t when g i b b e r e l l i n was s p r a y e d on to m a to p l a n t s ,
in c r e a s e d r e s p i r a t i o n , p h o to s y n th e s is and t r a n s p i r a t i o n to o k p la c e w ith ­
i n 5 o r 6 h o u r 's .
The s i g n i f i c a n c e o f g i b b e r e l l i n s i n r o o t d e v e lo p m e n t a n d i n r o o t
tr a n s lo c a tio n h as n o t been s tu d ie d v e ry e x te n s iv e ly ,
Z w eig e t a l .
(5 l)
o b s e r v e d t h a t when a r a d i o a c t i v e s o l u t i o n o f g i b b e r e l l i n w as a p p l i e d as
a d r o p on t h e l e a f s u r f a c e s i g n i f i c a n t m ovement o f -C^' g i b b e r e l l i n was
-10=
fo u n d i n r o o t s o f b e a n p l a n t s , b u t n o t i n c o r n .
T hey a t t r i b u t e d t h e
w i d e - s p r e a d d i s t r i b u t i o n o f 'g i b b e r e l l i h i n t h e b e a n p l a n t s t o x y lem .as
w e l l a s p h lo em t r a n s p o r t 0
O n ly p h lo em m ovem ent was n o t e d i n c o r n p l a n t s .
I t h a s b e e n r e p o r t e d (lj.3) t h a t when s m a l l a p p l i c a t i o n s o f g i b b e r e l I i n a r e a p p l i e d t o t h e t i p s o f p e a a n d b e a n c u t t i n g s , t h e ste m s e x te n d e d
b u t r o o t i n g was h o t a f f e c t e d .
When i n d o l e c e t i c a c i d a n d g i b b e r e l l i n
w e re used, i n c o m b in a tio n , ste m e x t e n s i o n o c c u r r e d p l u s a n i n c r e a s e i n
t h e num ber o f r o o t s .
The am ount o f n a t u r a l l y o c c u r r i n g p l a n t r e g u l a t o r s
p r e s e n t i n t h e p l a n t a t t h e tim e o f t r e a t m e n t was c o n s id e r e d t o b e im ­
p o r ta n t i n th e re sp o n se o b ta in e d .
D i f f e r e n c e s i n M o rp h d Io g y
Shoot C h a ra c te ris tic s
The s e l e c t i v e a c t i o n o f h e r b i c i d e s i s i n f l u e n c e d b y t h e s t r u c t u r e
and p h y s ip lo g y o f th e p l a n t ( 1 5 ).
'C e r ta i n m o r p h o lo g ic a l c h a r a c t e r i s t i c s
s u c h a s t h e n a t u r e a n d t h i c k n e s s o f c u t i c l e an d t h e num ber o f s t o m a t a l
o p e n in g s , a p p e a r t o b e q u i t e i n f l u e n t i a l i n c o n t r o l l i n g t h e r a t e and
am ount o f a b s o r p t i o n b y p l a n t s u r f a c e s .
I n p e n e t r a t i o n s t u d i e s con­
d u c te d b y D ay ( 1 7 ) , 2 , U-D r e q u i r e d a b o u t an h o u r t o t r a v e l t h e f i r s t 30
m ic r o n s , o n c e i n t h e p h lo em t r a n s l o c a t i o n was much m ore r a p i d , b e tw e e n
10= 100 c e n t i m e t e r s p e r h o u r .
The i n i t i a l few m i l l i m e t e r s h a v e b e e n
re c o g n iz e d as im p o rta n t b a r r i e r s t o r a p id a b s o rp tio n and t r a n s l o c a t i o n
o f exogenous m a t e r i a l s .
H ow ever, t h e m echanism b y w h ic h p e n e t r a t i o n i s
a c c o m p lis h e d i s n o t e n t i r e l y c l e a r .
W eaver an d DeRose (U 8 ) c o n c lu d e d
t h a t t h e p r i n c i p a l p a th w a y f o r p e n e t r a t i o n was th r o u g h t h e c u t i c l e .
—11—
T h e y s e l e c t e d p l a n t s h a v in g s to m a ta o n l y on t h e i r u p p e r s u r f a c e s , t r e a t e d
t h e u p p e r a n d lo w e r s u r f a c e s s e p a r a t e l y w i t h 2 ,U -D , a n d o b s e r v e d a s im i ­
l a r i n h i b i t i n g re s p o n s e f o r b o th tr e a tm e n ts .
H u ll (2 8 ) in d ic a te d t h a t
t h e am ount o f p e n e t r a t i o n b y 2 , U-D may b e r e l a t e d t o t h e t h i c k n e s s o f
th e c u ti c le .
B u t, o t h e r c o n s i d e r a t i o n s s u c h a s c o n t i n u i t y a n d t h e d e ­
g r e e o f h y d r a t i o n o f t h e c u t i c l e a r e p o s s i b l y m ore i m p o r t a n t .
C r a f t s ’ ( 1 3 ) w o rk w i t h
l a b e l l e d com pounds i n d i c a t e s t h a t t h e r e
a r e tw o r o u t e s fro m t h e l e a f s u r f a c e i n t o t h e v a s c u l a r t i s s u e , a l i p o i d a l and an aqueous r o u t e .
The d i n i t r o p h e n o l s ' a n d p h e n o x y pompounds a r e
h i g h l y c o m p a tib le w i t h t h e c u t i c l e a n d p e n e t r a t e t h e l e a f s u r f a c e r a p i d ­
ly .
Van O v e rb e e k (U ?) fo u n d t h a t f o r m u l a t i o n s c o n t a i n i n g a s u r f a c t a n t
s p r e a d b e t t e r , rem o v ed a i r f i l m s b e tw e e n s o l u t i o n s a n d t h e c u t i c l e and
p ro b a b ly p e rm itte d s to m a ta l p e n e tr a tio n to ta k e p la c e .
C u r r i e r a n d D y b in g ( 1 6 ) u s e d a f l u o r e s c e n t d y e t e c h n i q u e t o demon­
s t r a t e t h a t when s to m a ta w e re o p e n an d an e f f e c t i v e s u r f a c t a n t was u s e d ,
s t o m a t a l u p ta k e was r a p i d .
I n a r e v ie w o f a l l a v a i l a b l e I n f o r m a t i o n ,
t h e y c o n c lu d e d t h a t b o t h s to m a ta and t h e c u t i c l e a r e p r o b a b l y i n v o lv e d
i n t h e p e n e t r a t i o n o f c h e m ic a l s p r a y s .
H anson an d E udd (2 2 ) made r e f e r e n c e t o t h e t h i c k l a y e r o f c u t i n on
t h e u p p e r l e a f s u r f a c e a n d to w a rd s t h e m a r g in s o f l e a f y s p u r g e l e a v e s .
C r a f t s ( lU ) c a u t i o n s t h e u s e o f g re e n h o u s e grow n p l a n t s i n h e r b i ­
c id e a b s o r p t i o n s t u d i e s , b e c a u s e t h e y o n l y p ro d u c e a r e l a t i v e l y t h i n
c u tic le .
L e a f y s p u r g e s t o m a t a l c o u n ts w ere r e p o r t e d b y tw o g r o u p s .
H anson
and Rudd ( 2 2 ) c o u n te d 77 on t h e u p p e r l e a f s u r f a c e and 108 s to m a ta on
-12th-e lo w e r l e a f s u r f a c e p e r .s q u a re m i l l i m e t e r .
Bakke ( 3 ) r e p o r t e d a b o u t
-117 s to m a ta on t h e u p p e r a n d a b o u t 216 p e r s q u a r e m i l l i m e t e r on t h e
lo w e r l e a f s u r f a c e .
E n v ir o n m e n ta l c o n d i t i o n s a r e a l s o r e c o g n i z e d a s b e i n g i n f l u e n t i a l
i n a l t e r i n g t h e p h e n o ty p e o f some l e a f y s p u r g e s e l e c t i o n s .
B akke ( 3 )
r e p o r t e d t h a t w hen t h e g ro u n d i s m o is t t h e l e a v e s become l a r g e r , m ore
a b u n d a n t and t h e i n d i v i d u a l p l a n t s t a l l e r .
He a l s o fo u n d t h a t t h e r e
was c o n s i d e r a b l e v a r i a t i o n i n t h e g l a n d s on p l a n t s t h a t he e x a m in ed i n
Io w a .
Even t h e s h a p e o f g la n d s on a g i v e n p l a n t w e re f o u n d t o b e v a r i ­
a b le .
Some o f t h e s e m o r p h o l o g ic a l d i f f e r e n c e s i n l e a f y s p u r g e h a v e b e e n
tra c e d to
germ p la s m d i f f e r e n c e s .
■
G roh ( 1 9 ) i n d i c a t e d t h a t s t e r i l e
s h o o ts h a d much n a r r o w e r l e a f w id th s t h a n f e r t i l e
s h o o ts .
M oore a n d
L in d s a y ( 35 ) n o t e d t h a t on E u p h o r b ia c y p a r i s s i a s , t h e u p p e r l e a f e p i ­
d e rm is c e l l s on t e t r a p I o i d p l a n t s
(GnsiUo)
w ere c o n s p ic u o u s ly l a r g e r t h a n
e p id e r m a l c e l l s on d i p l o i d p l a n t s ( 2 n = 2 0 ).
T h is f i n d i n g h a s r e s u l t e d i n
a s im p lif ie d p ro ce d u re in c la s s if y in g th e lo c a tio n o f s t e r i l e
and f e r t i l e
i n f e s t a t i o n s o f t h i s w eed .
Root Characteristics
C o u p la n d and A le x ( 1 2 ) r e p o r t e d t h a t r o o t s v a r i e d n o t o n l y b e tw e e n
s p e c i e s b u t a l s o so m e tim e s w i t h i n s p e c i e s .
I n p e r e n n i a l w eed s s u c h a s
l e a f y s p u r g e t h e ty p e o f v e r t i c a l d i s t r i b u t i o n o f t h e r o o t s y s te m was
a ls o im p o rta n t i n r e l a t i o n to c o n tr o l ( 11) .
-13D orm ancy
The o n s e t o f d o rm an cy d u r in g t h e f a l l m o n th s i n p e r e n n i a l s p e c i e s
has b een o b se rv e d b y s e v e r a l i n v e s t i g a t o r s .
M eyer and A n d e rso n (3 2 )
n o te d t h a t b u d s o f m any woody p l a n t s p e c i e s re m a in e d d o rm a n t th r o u g h
autum n a p d i n t o t h e f i r s t p a r t o f w i n t e r ,
T hey i n d i c a t e d t h a t t h i s ty p e
o f d o rm a n c y was n o t c a u s e d b y low t e m p e r a t u r e s , b u t i t
c o u ld b e b ro k e n
b y s u b j e c t i n g t h e s e p l a n t s t o low t e m p e r a t u r e s o f a few d a y s t o s e v e r a l
w eek s.
M onson a n d S h a f e r (3 3 ) f o u n d t h a t t h i s ty p e o f do rm an cy on l e a f y
s p u r g e i s b r o k e n n a t u r a l l y b y low t e m p e r a t u r e s d u r in g t h e e a r l y w i n t e r .
I n c o r r e s p o n d e n c e w i t h D odson ( 1 8 ) , he r e p o r t e d t h e o n s e t o f dorm ancy
i n l e a f y s p u r g e c o u ld b e p r e v e n t e d i n g re e n h o u s e p l a n t s b y l e n g t h e n i n g
th e p h o to p e rio d .
METHODS AND MATERIALS
1MLth t h e c o o p e r a t i o n o f r e s e a r c h w o rk e rs i n s u r r o u n d i n g s t a t e s and
one p r o v in c e i n
C anada, a p p r o x i m a t e ly 10 r o o t s e c t i o n s m e a s u r in g 8 -1 2
i n c h e s l o n g w ere c o l l e c t e d an d s e n t t o Bozeman d u r in g t h e l a t e summer
and f a l l o f 1961,
T h e se w e re w ra p p e d i n m o is t p a p e r , p l a c e d i n p l a s t i c
b a g s and s h ip p e d b y p a r c e l p o s t .
i m m e d ia te ly p l a n t e d i n
in s o il.
A l l a r r i v e d i n good s h a p e a n d w ere
c a n s 6 i n c h e s i n d i a m e te r b y 18 i n c h e s i n d e p th
E ach c o l l e c t i o n was c o n s i d e r e d t o b e a s t r a i n .
The s o u r c e a n d
i d e n t i f y i n g p r e f i x e s a r e l i s t e d b e lo w :
SOURCE
PREFIX
■SOURCE
C o lo ra d o -------- ------------COL
Id a h o ----------- —------------IDA
M o n ta n a '
M o c c a s in - - — ------ M .I
M is s o u la — — ------ M .I I
Bozem an ----- -------- M o III
PREFIX
N o rth D a k o ta
F a rg o ------------ ' "L e o n ard '--------S o u th D a k o ta ' — -—
A l b e r t a , Canada. -
ND I
ND I I
S.Do
CAN
C y to lo g ic a l P ro c e d u re s
F o r c y t o l o g i c a l s t u d i e s t h e tw o s t r a i n s d i f f e r i n g m o st w i d e ly i n
m o r p h o lo g ic a l c h a r a c t e r i s t i c s w e re e x a m in e d ,
F or th e s e s tu d ie s p la n ts
w e re p r o p a g a t e d i n v e r m i c u l i t e i n f l a t s u s i n g a n u t r i e n t s o l u t i o n .
■The f l a t s w e re w a t e r e d w i t h 5>00 m l o f B o n n e r 's p e a r o o t m edium .
was m o d if ie d as d e s c r i b e d u n d e r
It
Im p ro v e d Medium" b y T o r r e y (lj.6 )" e x c e p t
f o r s u c r o s e a n d t h e v i ta m i n s ( t h i a m i n a n d n i c o t i n i c a c i d ) w h ic h w e re e x ­
c lu d e d fro m t h e s t o c k s o l u t i o n .
A lso a t a b l e s p o o n o f 2 0 - 2 0 -2 0 w a te r,
s o l u b l e f e r t i l i z e r was a d d e d p e r 3 l i t e r s
o f n u trie n t s o lu tio n .
Once p l a n t s w ere e s t a b l i s h e d and m ak in g r a p i d g ro w th t h e r o o t t i p s
■-15”
w ere p r e t r e a t e d a n d c o l l e c t e d a s o u t l i n e d b y S c h e r t z and R a n d o lp h (I4O ).
The f o l l o w i n g s t e p s w ere t a k e n t o sm e a r t h e r o o t t i s s u e ,
1,
The r o o t t i p s w ere rem oved fro m t h e f i x i n g f l u i d and
w ash ed i n r u n n in g c o o l t a p w a t e r f o r 30 m in u t e s .
2.
R o o t t i p s w ere p l a c e d i n a 1$ a q u e o u s s o l u t i o n o f p e c t i n o l f o r 3 h r s a t 1|5° € .
F o r i n s t r u c t i o n s on p r e p a r a t i o n
s e e S c h e r t z a n d R a n d o lp h (lj.0).
3«
A p i c a l p o r t i o n s o f r o o t s w ere h y d r o ly z e d i n IN HCL a t : 6o° C
f o r 8 -1 0 m in u t e s .
Iu
R oot t i p s w ere p l a c e d on a w a tc h g l a s s c o n t a i n i n g a few
d ro p s o f
o r c e i n f o r 1 -3 m i n u t e s ,
L im ite d h e a t was
a p p l i e d t o t h e b o tto m o f t h e w a tc h ' g l a s s t o make i t warm
to to u c h .
5.
R o o ts w e re rem o v ed fro m %% o r c e i n and p l a c e d on a g l a s s
s l i d e w ith a d ro p o f 1$ o r c e i n s o l u t i o n .
6.
R o o t t i s s u e was c r u s h e d w i t h a ro u g h s u r f a c e d . p e s t l e ,
7.
The c o v e r s l i p was t h e n p l a c e d o v e r t h e m a t e r i a l and l i g h t ,
e v e n p r e s s u r e was a p p l i e d w i t h t h e p a lm o f h a n d t o
sp re a d
th e c e l l u l a r m a te r ia l o u t e v e n ly .
F i n i s h e d s l i d e s w e re i n v e s t i g a t e d w i t h a b i n o c u l a r m ic r o s c o p e .
p o w er (1 2 3 X) was u s e d t o s e a r c h f o r g o o d c e l l s .
Low
Chromosome i n v e s t i g a ­
t i o n s w ere made w i t h h i g h p o w er (1 2 5 0 X ).
An a t t e m p t was made t o u s e p o l l e n m o th e r c e l l s
f o r h a p l o i d c o u n ts ;
h o w e v e r, s u f f i c i e n t s u i t a b l e m a t e r i a l was l a c k i n g f o r t h i s p r o c e d u r e .
-16-
D i f f e r e n c e s i n P h y s i o l o g i c a l R e sp o n se
P l a n t P r e p a r a t i o n an d 2 , Ii-D T r e a tm e n ts
T w o -q u a rt p a p e r m ilk c a r t o n s f i l l e d w i t h H u f f in e S i l t Loam s o i l
w e re u s e d t o v e g e t a t i v e I y p r o p a g a t e s e v e r a l p l a n t s fro m e a c h o f t h e n i n e
s tra in s .
T h e se p l a n t s w e re grow n i n t h e g r e e n h o u s e u n t i l s h o o t h e ig h t
a v e r a g e d 6 -8 i n c h e s .
F iv e u n ifo r m p l a n t s w ere s e l e c t e d f o r e a c h s t r a i n .
T h re e o f t h e s e w ere t r e a t e d w i t h a 0 .5 T b /a c r e r a t e o f 2,1|.-D am ipe and
two w e re r e s e r v e d a s c h e c k s .
T r e a tm e n ts w e re a p p l i e d w i t h a k n a p s a c k
s p r a y e r e q u ip p e d w i t h an 8002 t e e j e t n o z z l e .
A c o n s ta n t a i r p r e s s u r e o f
31 p o u n d s was a d m i tt e d i n t o t h e s p r a y e r t h r o u g h a p r e s s u r e r e g u l a t i n g
v a lv e .
The p l a n t s w ere p l a c e d on a m oving b e l t w h ic h p a s s e d th em a t a
c o n s ta n t sp e ed u n d e r th e s p ra y in g n o z z le .
A s u r f a c t a n t (X -77). wqs u s e d
a t a r a t e o f 0 .5 p t /1 0 0 g a l l o n s on a l l c h e m ic a l t r e a t m e n t s ,
T r e a tm e n t r e s u l t s w ere e v a l u a t e d v i s u a l l y .
The am ount o f e p i n a s t y ,
c h l o r o s i s * n e c r o s i s and g ro w th a b e r r a t i o n s w ere th e c r i t e r i a u s e d i n d e ­
te rm in in g th e r e l a t i v e s u s c e p t i b i l i t y o r r e s i s t a n c e o f a g iv e n s t r a i n .
A s e c o n d 2 * U-D t o l e r a n c e t e s t was c o n d u c te d w i t h p l a n t s o f d i f f e r e n t
s iz e s *
T h re e , u n ifo r m p l a n t s w e re s e l e c t e d a t e a c h o f t h r e e h e i g h t s
O - U s 5 - 6 an d 7 -9 i n c h e s ) .
Two p l a n t s fro m e a c h 'h e i g h t c a t e g o r y w ere
t r e a t e d w i t h 2*U-D am ine a t a r a t e o f 0 .2 5 p o u n d s p e r a c r e .
T h re e o t h e r
p l a n t s fro m e a c h s t r a i n w e re h a r v e s t e d b y c l i p p i n g a t g ro u n d l e v e l w ith
t h e g r e e n 't o p g ro w th b e i n g w e ig h e d .
The c h e m ic a l was a p p l i e d w i t h a p e rfu m e a to m iz e r u s i n g w a t e r a s t h e
c a r r i e r a t a r a t e e q u a l t o 80 g a l l o n s p e r a c r e .
The g ro w th r a t e a t t h i s
-17tim e o f t h e y e a r (N ovem ber) was s lo w e v e n when s u p p le m e n ta l l i g h t i n g was
p r o v id e d t o g iv e a d a y l e n g t h o f Ilj. h o u r s .
Two w eeks a f t e r t r e a t m e n t i t was a p p a r e n t t h a t t h e p l a n t s w ere n o t
r e s p o n d i n g t o t h e c h e m ic a l t r e a t m e n t a n d a s e c o n d a p p l i c a t i o n was made
a t th e same r a t e a s t h e f i r s t .
One m onth l a t e r , t o p g ro w th was -c lip p e d
fro m e a c h c a r t o n a t g ro u n d l e v e l a n d w e ig h e d .
T h e se w e ig h ts w e re com­
p a r e d t o t h o s e 1o b t a i n e d a t t h e tim e o f t h e f i r s t t r e a t m e n t .
I n t h i s way
t h e h e r b i c i d a l a c t i o n on d i f f e r e n t s t r a i n s c o u ld b e com pared q u a n t i t a ­
tiv e ly .
A 0 .5 l b / a c r e r a t e o f 2 , U-D was a p p l i e d t o one r e p l i c a t i o n o f
s t r a i n s t o d e te r m in e w h e th e r t h e y v a r i e d i n t h e i r r a t e o f sh o o t- g ro w th
a f t e r tre a tm e n ts .
S h o o t m e a su re m e n ts w e re r e c o r d e d i n c e n t i m e t e r s e v e r y
tw o d a y s f o r t r e a t e d and c h e c k p l a n t s .
G la s s f a c e d b o x e s , m e a s u r in g 3<>5> x 10 x 30 i n c h e s , w e re f i l l e d w i t h
v e r m i c u l i t e and u s e d t o m e a su re d a i l y r o o t g ro w th o f t r e a t e d a n d un­
tre a te d p la n ts .
T h e se p l a n t s w e re w a t e r e d w e e k ly w i t h 3 0 0 "ml o f th e
n u tr ie n t s o lu tio n r e f e rr e d to e a r l i e r .
An o p aque c o v e r w as p l a c e d o v e r
t h e g l a s s t o e x c lu d e a l l l i g h t fro m t h e r o o t s , e x c e p t when r e c o r d i n g
o b s e rv a tio n s .
R o o ts grew a g a i n s t t h e g l a s s w hen b o x e s w e re p l a c e d a t a
60 ° a n g le w i t h t h e f l o o r .
Two y o u n g p l a n t s (U -611 s h o o t s ) o f a s i n g l e s t r a i n w e re p l a c e d i n
each box.
A f t e r one w eek o f g ro w th a l l e x c e p t 3 o r I), m a in r o o t s w ere
c l i p p e d so a w o rk a b le num ber o f r o o t s c o u ld b e m e a s u re d .
Once e x c e s s
r o o t s w e re trim m e d b a c k , r o o t a p i c a l d o m in an ce p r o h i b i t e d new l a t e r a l s
fro m d e v e lo p i n g .
—18I n e a c h b o x one p l a n t was t r e a t e d w i t h a 0 ,£ l b / a c r e r a t e o f 2} h~'D>
The o t h e r p l a n t was p r o t e c t e d fro m s p r a y w i t h a p a p e r b a g so i t
u t i l i z e d as a ch eck .
S p r a y in g was a c c o m p lis h e d w i t h an a r t i s t ' s
c o u ld b e
a ir
b r u s h , w h ic h a p p l i e d a f i n e m is t, o f s p r a y s o l u t i o n t h a t c o v e re d t h e e n ­
tir e p la n t.
The p l a n t r e s p o n s e o b t a i n e d b y a p p ly in g 2 , U-D w i t h an a t ­
o m iz e r , k n a p s a c k s p r a y e r a n d a n a r t i s t ' s
a i r b r u s h w ere f o u n d t o b e
s im ila r.
The d a i l y r a t e o f r o o t g ro w th was r e c o r d e d fro m a few da.ys b e f o r e
t r e a t m e n t u n t i l t h e t r e a t e d p l a n t s c e a s e d g ro w in g o r u n t i l t h e r o o t s
grew t o t h e b o tto m o f t h e i r b o x e s .
P l a n t P r e p a r a t i o n an d G i b b e r e l l i n T r e a tm e n ts
.
A h i g h l y p u r e fo rm o f g i b b e r e l l i c a c i d po w d er was u s e d f o r t h e s e
tre a tm e n ts ,
A 0 ,5 p t / 1 0 0 g a l r a t e o f s u r f a c t a n t (X 7 7 ) was a l s o m ixed
i n th e s p ra y s o lu t i o n s ,
G i b b e r e l l i c a c i d w as a p p l i e d t o t h e t o p g ro w th a n d 't o t h e s o i l as
a ro o t tre a tm e n t.
S o i l t r e a t m e n t s w ere made b y a p p ly i n g 50 m l o f a 100
ppm s o l u t i o n o f g i b b e r e l l i c a c i d t o tw o p l a n t s f o r e a c h s t r a i n .
Shoot
h e i g h t was m e a s u re d a t v a r i o u s i n t e r v a l s .
O th e r t r e a t m e n t s t o o b s e r v e r o o t and s h o o t g ro w th w e re c a r r i e d o u t
i n g la s s faced b o x e s.
P l a n t p r e p a r a t i o n a n d t r e a t m e n t s w e re s i m i l a r t o
t h o s e d e s c r i b e d f o r 2 ,U -D ,
G i b b e r e l l i c a c i d was s p r a y e d a s a .1000 ppm
s o l u t i o n u s i n g a v o lu m e e q u a l t o 80 g a l l o n s p e r a c r e on one o f tw o
p la n ts fo r each s tr a in
g ro w in g i n g l a s s f a c e d b o x e s .
s h o o t m e a s u re m e n ts w ere m ade,
-
B o th r o o t and
>
P r e l i m i n a r y t e s t i n g was c a r r i e d o u t t o d e te r m in e w h e th e r g i b b e r e l -
-19I i c a c i d w o u ld b e e f f e c t i v e i n i n c r e a s i n g t h e r e s p o n s e t o 2 ,U-D t r e a t ­
m e n ts ,
A f)00 ppm s o l u t i o n o f g i b b e r e l l i c a c i d was a p p l i e d 3 d a y s p r i o r
t o t r e a t m e n t w ith a 0 .3 I b / a e r e r a t e o f 2 5U-D.
ND I ) w e re u s e d i n t h i s t e s t .
Two s t r a i n s
(GAN and
T h e se s t r a i n s h a d p r e v i o u s l y shown d i f ­
f e r e n t l e v e l s o f s u s c e p t i b i l i t y t o 2,
Ii-D.
D i f f e r e n c e s i n M o rp h o lo g y
L eaf S tu d ie s
C u t i c l e t h i c k n e s s was i n v e s t i g a t e d b y c o l l e c t i n g l e a v e s fro m d i f f e r ­
e n t s t r a i n s t h a t w e re u n ifo r m i n s i z e and g ro w th c h a r a c t e r i s t i c s .
L e a v e s w e re c o l l e c t e d fro m t h e t o p s , m i d - s e c t i o n s a n d b o tto m s o f two
p l a n t s fro m e a c h s t r a i n .
B o th u p p e r an d lo w e r l e a f s u r f a c e s w ere
s tu d ie d .
L e a fy s p u rg e l e a v e s w e re p r e p a r e d , m o u n te d and s t a i n e d ,a c c o r d in g t o
t h e p r o c e d u r e s o u t l i n e d i n J o h a n s e n 's ( 2 9 ) " P l a n t M ic r o te c h n iq u e " .
T h is m eth o d was n o t s a t i s f a c t o r y b e c a u s e , upon m ic r o s c o p i c exam in­
a t i o n , i t becam e a p p a r e n t t h a t e i t h e r t h e p l a n t s h a d v e r y l i t t l e
c u tin
a n d wax on t h e i r l e a v e s o r t h e c u t i c l e was b e i n g rem oved i n t h e s t a i n ­
in g p ro c e s s .
An a l t e r n a t i v e m eth o d t o o b s e r v e and m e a su re t h e c u t i c l e was t r i e d .
F r e s h l e a v e s w ere h a r v e s t e d a n d p l a c e d b e tw e e n tw o p i e c e s o f J a p a n e s e
E ld e r p i t h ,
A t h i n r a z o r b l a d e was u s e d t o s l i c e v e r y t h i n c r o s s s e c ­
tio n s o f each l e a f .
T h e se t h i n s l i c e s w e re p l a c e d i n a d ro p o f 5$
a c e to c a r m in e on a m ic ro s c o p e s l i d e .
G o v e rs l i p s w ere p l a c e d o v e r t h e
m a t e r i a l a n d good l e a f c r o s s - s e c t i o n s w e re m e a s u re d w i t h a m ic r o s c o p e .
—20"
A s t a g e m ic r o m e te r was u s e d t o c a l i b r a t e t h e e y e o c u l a r s c a l e f o r a c c u r ­
a t e m e a s u re m e n ts .
P i c t u r e s w e re t a k e n t o show t h e t h i c k n e s s and t h e
d i s tr ib u tio n o f th e c u ti c le .
I t h a s b e e n s u g g e s t e d t h a t t h e num ber o f s to m a ta on p l a n t l e a f
s u r f a c e s c o u ld i n f l u e n c e t h e am ount o f a b s o r p t i o n and p e n e t r a t i o n o f a
h e rb ic id e .
I n t h i s t e s t s to m a ta c o u n ts w ere t a k e n fro m t h e d i f f e r e n t
s t r a i n s t o d e te r m in e w h e th e r s to m a ta num bers w ere c o r r e l a t e d w i t h th e
2 , 1|.-D r e s p o n s e o b t a i n e d .
C o u n ts w ere t a k e n fro m t h r e e a r e a s on b o t h t h e u p p e r and lo w e r l e a f
su rfa c e s.
B o th e p id e r m a l s t r i p s and c o l l o d i o n i m p r e s s i o n s w ere u s e d
o v e r a one y e a r p e r i o d t o d e te r m in e t h e num ber o f s to m a ta p e r mm^.
E p id e rm a l s t r i p s w ere t a k e n fro m e a c h l e a f a r e a and t r a n s f e r r e d
in to
a p o o l o f w a t e r o n a m ic r o s c o p e s l i d e , • T h ey w e re m a g n if ie d 320
t im e s a n d a l l s to m a ta w i t h i n t h i s f i e l d w e re c o u n te d .
Num bers f o r t h e
u p p e r and f o r t h e ' lo w e r s u r f a c e s w ere a v e r a g e d s e p a r a t e l y a n d m u l t i p l i e d
2
b y a c o n s t a n t t o g iv e t h e num ber o f s to m a ta p e r mm ,
C o llo d io n i m p r e s s i o n s w ere o b t a i n e d fro m th e u p p e r an d lo w e r s u r ­
f a c e s b y p l a c i n g Duco cem ent on l e a f s u r f a c e s an d p e e l i n g t h e c o l l o d i o n
o f f when i t becam e d r y .
The s to m a ta w e re c o u n te d i n a s i m i l a r m anner
t o t h e e p id e r m a l s t r i p s .
The s i z e a n d s h a p e o f e p id e r m a l c e l l s an d s to m a ta w e re a l s o ob­
s e r v e d d u r in g t h i s w o rk .
R oot O b s e rv a tio n s
R o o ts w e re f r e q u e n t l y e x a m in ed b y w a s h in g t h e s o i l fro m t h e r o o t s .
A t t h e s e t im e s th e c o l o r , s i z e and l e n g t h o f r o o t s fro m v a r i o u s s t r a i n s
-21w e re . o b se rv e d .
G la s s f a c e d b o x e s , w ere a l s o h e l p f u l i n s t u d y i n g t h e t y p e s o f r o o t
s y s te m s t h a t t h e d i f f e r e n t s t r a i n s e x h i b i t e d .
'
D orm ancy
T e s ts w e re c o n d u c te d i n t h e g r e e n h o u s e th r o u g h o u t t h e y e a r .
D u rin g
t h e f a l l a n d e a r l y w i n t e r m onths a l l s t r a i n s o f l e a f y s p u r g e grew p o o r ­
ly .
I n m id - F e b r u a r y a l l p l a n t s resu m ed m ore a c t i v e g ro w th p a t t e r n s .
L im ite d t r i a l s w e re c a r r i e d o u t t o overcom e t h i s t y p e o f se m i­
d o rm an cy b y e x te n d i n g t h e l e n g t h o f t h e l i g h t p e r i o d t o l i t h o u r s w ith
in c a n d e sc e n t lig h t in g .
I n o t h e r t e s t s r o o t p i e c e s w e re w ra p p e d i n
m o is t p a p e r a n d p l a c e d i n a p l a s t i c b a g i n th e r e f r i g e r a t o r a t 35>° F ,
A f t e r 1 - 3 m onths a t t h i s t e m p e r a t u r e r o o t p i e c e s w ere p l a n t e d i n s o i l
i n th e g ree n h o u se .
I
RESULTS
R o o t s e c t i o n s o f l e a f y s p u rg e w e re c o l l e c t e d fro m n i n e d i f f e r e n t
l o c a t i o n s i n t h e U n ite d S t a t e s , an d ^'Canada.
Some o f th em im m e d ia te ly
b e g a n t o grow a n d p r o d u c e d good r o o t a n d s h o o t d e v e lo p m e n t.
O th e rs ■
e x h i b i t e d a s e m i-d o rm a n c y i n t h a t a s h o r t g r e e n s h o o t was p r o d u c e d and
no f u r t h e r g ro w th o c c u r r e d .
Some s e c t i o n s , p r i m a r i l y t h o s e a t t a c h e d t o
t h e crow n f a i l e d t o p r o d u c e r o o t s .
s e c t i o n s w ere a c t u a l l y r o o t s .
I t was n o t d e te r m in e d t h a t t h e s e
T hey may h a v e b e e n u n d e rg r o u n d ste m s o r
com posed o f t i s s u e r e p r e s e n t i n g a t r a n s i t i o n zone b e tw e e n s te m a n d r o o t .
Once t h e p l a n t s w ere i n i t i a l l y e s t a b l i s h e d no d i f f i c u l t y was en­
c o u n te r e d i n v e g e t a t i v e I y p r o p a g a t i n g a d d i t i o n a l p l a n t s .
R oot s e c tio n s
fro m 2 -3 mm i n d i a m e te r and fro m 3 -5 cm i n l e n g t h w o u ld u s u a l l y d e v e lo p
a s h o o t.
C y t o l o g i c a l F in d in g s
S l i g h t v a r i a t i o n i n t h e s i z e and s h a p e o f l e a f y s p u rg e l e a v e s h a s
c a u s e d c o n s i d e r a b l e c o n f u s i o n , e v e n among t a x o n o m is t s , r e g a r d i n g i t s
p ro p er b o ta n ic a l c la s s if ic a tio n .
V a r i a t i o n was o b s e rv e d i n t h e
t i o n s c o l l e c t e d , an d tw o o f t h e m ost d i v e r g e n t s t r a i n s
s e le c - .
(CAN a n d ND I )
w ere s e l e c t e d f o r chrom osom e i n v e s t i g a t i o n s , s e e F i g u r e I .
E u p h o r b ia
e s u l a , a c c o r d in g t o M oore (3 lt) a n d P r i t c h a r d ( 3 9 ) h a s a s o m a tic chrom o­
some num ber o f 6 0 .
A s l i d e was o b t a i n e d w i t h a s q u a s h t e c h n i q u e t o c o n fir m t h a t t h e
ND I s e l e c t i o n h a s a 2n=6o chrom osome n u m b e r.
A ll a tte m p ts t o g e t th e
I
-25-
Figure I . Two d i f f e r e n t s t r a i n s o f l e a f y sp u r g e . The e i g h t
in c h sh o o ts above r ep re se n t th e Canadian and th e North
Dakota I s e l e c t i o n s . Below are th e l e a f shapes from th e
t o p , m id - s e c t io n and basal p o r tio n o f th e sh o o ts f o r each
str a in .
-2 b e x a c t chrom osom e num ber o f t h e C a n a d ia n s t r a i n w e re u n s u c c e s s f u l .
A
p h o to m ic r o g r a p h o f chrom osom es fro m t h e ND I s t r a i n i s shown i n F ig u r e 2
t o g e t h e r w i t h one made fro m C anada t h i s t l e
( 2n.-3b ) .
T h e se p h o to g ra p h s
show t h e r e l a t i v e s i z e o f t h e chrom osom es a n d t h e d i f f i c u l t y e n c o u n te r e d
i n m aking chrom osom e c o u n ts i n l e a f y s p u r g e b e c a u s e o f t h e i r s m a ll s iz e *
■With t h e p o s s i b l e e x c e p t i o n o f t h e
C a n a d ia n s e l e c t i o n , a l l p l a n t s
s t u d i e d a p p e a r e d t o m ee t t h e m o r p h o lo g ic a l r e q u i r e m e n ts f o r E u p h o r b ia
e s u la .
Differences in P hysiological Response to Growth Regulating Chemicals
S h o o t and R oot R esp o n ses t o
2 , L-D
I t h a s b e e n d e m o n s tr a te d t h a t v a r i a t i o n i n r e s i s t a n c e t o
a g iv e n
h e r b i c i d e e x i s t s w i t h i n some p l a n t s p e c i e s ( 8 , 26 , 5>0 ) .
To d e te r m in e i f s u c h v a r i a b l e r e s i s t a n c e was p r e s e n t i n l e a f y
■
s p u r g e t h r e e u n ifo r m p l a n t s o f a l l s e l e c t i o n s w e re t r e a t e d on May 8 ,
1 9 6 2 , w i t h 2 , U-D am ine a t a r a t e o f 0 .5 I b / a c r e .
T h e se p l a n t s w ere
v i s u a l l y e v a l u a t e d I , 3 , 8 , 13 and 30 d a y s a f t e r t r e a t m e n t .
P l a n t t o p g ro w th a p p e a r e d t o re s p o n d , s i m i l a r l y f o r t h e f i r s t t h r e e
days a f t e r tre a tm e n t.
B y t h e e i g h t h d a y some p l a n t s h a d b e g u n t o t u r n
c h l o r o t i c w h i l e o t h e r s re m a in e d g r e e n .
By t h e 1 3 th d a y , c e r t a i n s t r a i n s
a p p e a r e d t o b e m a r k e d ly m ore t o l e r a n t t o 2 , U-D t h a n o t h e r s .
S h o o ts o f
t h e s e s t r a i n s w e re sh o w in g s i g n s o f b e c o m in g n e c r o t i c w h i l e t h o s e from
o t h e r s t r a i n s w e re g r e e n a n d sh o w in g o n l y s l i g h t e p i n a s t i c e f f e c t s .
One month after treatments, the d iffe r e n tia l response of top growth
was s t i l l very noticeab le.
Many green leaves remained on strains that
-25-
4
Figure 2 . Photomicrographs o f Ciraium a rv en a e, 2 n = )4 , (above)
and Euphorbia e e u l a , 2 n = 6 0 , ( b e l o w ) ; showing r e l a t i v e s i z e s
o f chromosomes. (M a g n ifica tio n c a . 525 OX) (Canada t h i s t l e
chromosome photo c o u r te s y o f Frank Thrasher, USDA, ARS)
—
26—
a p p a r e n t l y w e re m ore r e s i s t a n t t o t h e a c t i o n o f 2 ,1 |-D .
S h o o ts o f o t h e r
s t r a i n s h a d d i e d b a c k a n d w e re d e v e lo p i n g new b u d s a n d s h o o t s , i n d i c a ­
tin g th a t l i t t l e
dam age h a d b e e n done t o t h e r o o t s .
In t h i s p re lim in a ry
t e s t to p g ro w th o f t h e s t r a i n fro m C anada was k i l l e d m o st c o m p le te ly ■
w h i l e ND I a p p e a r e d t o b e t h e m o st r e s i s t a n t .
To h e l p s u b s t a n t i a t e t h e s e r e s u l t s a d d i t i o n a l 2, Ii-D t r e a t m e n t s
w e re m ade.
A p p l i c a t i o n r a t e s r a n g e d fro m 0 .2 5 t o 1 . 0 p o u n d s p e r a c r e .
V i s u a l o b s e r v a t i o n s fro m t h e s e e a r l y 2 , Ii-D t r e a t m e n t s a r e p r e s e n t e d i n
TABLE I .
Some v a r i a b i l i t y o f p l a n t r e s p o n s e was o b s e rv e d b e tw e e n
p l a n t s o f t h e same s t r a i n i n t h e s e t e s t s a t t h e 0 .5 l b r a t e o f 2 ,Ii-D . .
H ow ever, a s t h e 2 , Ii-D r a t e was i n c r e a s e d , t o p g ro w th o f a l l p l a n t s was
i n j u r e d m ore e x t e n s i v e l y .
p la n ts
T h is made i t m ore d i f f i c u l t t o c l a s s i f y t h e
as t o t h e i r r e l a t i v e t o l e r a n c e .
"When th e a v e ra g e r a t i n g i s
t o t a l e d f o r e a c h s t r a i n f o r a l l r a t e s o f 2 , L-D, i t i s
e a s y to p ic k th o s e
p l a n t s w hose t o p g ro w th a p p e a r e d t o b e m o st s u s c e p t i b l e an d t h o s e t h a t
w ere a p p a r e n t l y t h e m o st t o l e r a n t .
I n a n a t t e m p t t o v e r i f y t h e v i s u a l m ethod o f r a t i n g 2? L-D r e a c t i o n s ,
a n e x p e r im e n t was s e t up t o o b t a i n q u a n t i t a t i v e d a t a fro m t h e s e same
l e a f y s p u rg e s t r a i n s .
T he s lo w g ro w in g p l a n t s f a i l e d t o r e s p o n d t o
2 , L-D a t a 0 .2 5 I b / a c r e r a t e an d w e re t r e a t e d a g a in two w eeks l a t e r .
E ven w i t h a d o u b le r a t e o f 2 , L-D t h e p l a n t s d i d n o t show 2 , L-D i n j u r y
t o t h e same e x t e n t a s t h o s e t h a t w ere t r e a t e d a t o t h e r t im e s o f t h e
y e a r.
F o r t y - f i v e d a y s a f t e r t h e f i r s t t r e a t m e n t t h e p l a n t s w ere h a r C
v e s te d .
G re e n w e ig h ts o f t h e to p g ro w th a r e g r a p h i c a l l y p r e s e n t e d i n
F ig u re 5 as a p e rc e n t o f th e u n tr e a te d c h e c k s.
W h ile som ew hat l e s s
-
-27-
TABLE I .
The r e l a t i v e t o l e r a n c e o f n i n e s t r a i n s o f l e a f y
s p u r g e t o 2 , L-D a s e v a l u a t e d b y v i s u a l m e a n s .
I
A ve.. Ratings""" f o r t h r e e
S tra in
S o u rc e
.
0 .2 5 lb /A
2 R eps.
■ 0 .9
'Tb/A
9 R ens.
2 , L-D r a t e s .
1 .0 T b/A
2 R ens.
Mean F i n a l
t o ta l ra tin g
S .D .
3 .0
2 .0
1 .0
6
I
M. I l l
2 .0
2. L
2 .0
6 .L
2
HD I
1 .0
2 .0
6 .0
9 .0
.3 ■
ND I I
L.o
9 .2
3 .0
12.2
L
IDA
6 .0
6 .8
L.o
,1 6 .8
. 9
COL
9 .o
7 .L
9 .o
1 7 .L
6
M. I
8 .0
L.2
8 .0
.2 0 .2
7
I CM
7 .0
8 .2
7 .0
2 2 .2
8
9 .0
6 .8
9 .0
2 L .8
9
M .I I
R a t in g s w e re I t o 9 w i t h I r e p r e s e n t i n g t h e m o st
tp le ra n t o r r e s is ta n t s tra in .
.
-28-
TOLERANCE RATING1
ND I I
IDA
STRAIN
F i g u r e 3 . The a v e r a g e i n c r e a s e 'i n w e ig h t o f to p g row th' fro m n in e
l e a f y s p u rg e s t r a i n s e x p r e s s e d a s a p e r c e n t o f t h e c h e c k h$
d a y s a f t e r t r e a t i n g w i t h 2 5h-D ."
^T op g ro w th froin' c h e c k ' p l a n t s " was H a r v e s te d and w e ig h e d a t
t h e tim e o f t r e a t m e n t . F o r t y - f i v e 'd a y s l a t e r t h e t r e a t e d
p l a n t s (6 fro m e a c h s t r a i n ) w e re " h a r v e s te d " 'a n d w e ig h e d .
C h e c k 'w e ig h ts were" s u b t r a c t e d fro m t h e ' t r e a t e d w e i g h ts a n d
t h e r e m a in d e r e x p r e s s e d as a p e r c e n t a g e . Two 0 ,2 3 l b / a c r e
r a t e s o f 2 , L-D w ere a p p l i e d on t r e a t e d m a t e r i a l ,
**F rom TABLE I .
■
'
-2 9
g ro w th was o b t a i n e d fro m t h e p l a n t s t h a t h a d p r e v i o u s l y b e e n r a t e d as
m ore s u s c e p t i b l e t o
2 , U-D a s t a t i s t i c a l a n a l y s i s d i d n o t show t h a t t h e
d i f f e r e n c e s i n t o p g ro w th w e re s i g n i f i c a n t a t t h e $% l e v e l .
' In d iv id u a l
p l a n t w e ig h ts a r e g iv e n i n APPENDIX TABLE I I .
A s t u d y o f t h e g ro w th r a t e o f s h o o ts f o r t h e f i r s t fe w d a y s a f t e r
t r e a t i n g w i t h a O.U l b / a c r e r a t e o f 2 , U-D was made on two o f t h e
s t r a i n s t h a t a p p e a r e d t o b e m ore s u s c e p t i b l e a n d tw o o f t h e s u p p o s e d ly
m ore t o l e r a n t s t r a i n s .
R e s u l t s w e re n o t c o n c l u s i v e b e c a u s e o f t h e l i m i ­
t e d num ber o f p l a n t s o b s e r v e d an d d u e t o t h e e r r a t i c b e h a v i o r o f t h e
u n tre a te d p la n ts o f th e s u s c e p tib le s t r a i n s .
F ig u re s U and 5 .
R e s u lts a re p r e s e n te d in
T h e re a p p e a r e d t o b e a s l i g h t s t i m u l a t i o n i n g ro w th
f o r t h e f i r s t 5 d a y s a f t e r t r e a t m e n t , a f t e r w h ic h t h e 2 , U-B s u s c e p t i b l e
s t r a i n s g a in e d no f u r t h e r l e n g t h .
The r e s i s t a n t s t r a i n s c o n ti n u e d t o
grow , h o w e v e r, a t a r e d u c e d r a t e .
The e f f e c t o f 2 , U-B- on l e a f y s p u r g e r o o t s was o b s e rv e d i n g l a s s
faced b o x es.
tre a tm e n t.
R o o t m e a su re m e n ts w ere made s e v e r a l d a y s b e f o r e a n d a f t e r
The r a t e o f g ro w th f o l l o w i n g t r e a t m e n t was a lm o s t c o n s t a n t
f o r f o u r d a y s a f t e r w h ic h i t d e c r e a s e d r a p i d l y u n t i l t h e t e n t h d a y when
r o o t g ro w th on t h e t r e a t e d p l a n t s w a s ' o n l y
ones.
T h e re a p p e a r e d to. b e l i t t l e
o f t h a t on t h e u n t r e a t e d
d i f f e r e n c e b e tw e e n t h e tw o s t r a i n s .
R e s u lts can be s e e n i n F ig u re 6 .
A g l a s s f a c e d b o x i s p i c t u r e d i n F i g u r e 7 , w i t h a t r e a t e d a n d an
u n tre a te d p l a n t .
■ tre a tm e n t.
The t r e a t e d p l a n t c e a s e d g ro w th tw e lv e d a y s a f t e r
-303 .0 u
/
2 .^
/
SHOOT GROWTH IN CM
/
SHOOT GROWTH IN CM
One r e p l i c a t i o n fro m e a c h o f t h e tw o m o st r e s i s t a n t s t r a i n s
(S .D . a n d M .I I I ) d e te r m in e d b y v i s u a l m ea n s.
T r e a te d
Check
10
DAYS AFTER TREATMENT
One r e p l i c a t i o n fro m e a c h o f t h e tw o s t r a i n s o f l e a f y s p u rg e
m ost s u s c e p t i b l e t o
( CAN and M .I) d e te r m in e d b y v i s u a l
m e a n s.
F i g u r e It. A bove: The a v e r a g e s h o o t g ro w th o f tw o r e l a t i v e l y r e s i s ­
t a n t s t r a i n s o f l e a f y s p u rg e a f t e r 2 , U-D t r e a t m e n t , com pared w ith
u n tre a te d ch eck s.
F i g u r e S . B elow j The a v e r a g e s h o o t g ro w th o f tw o r e l a t i v e l y s u s c e p t i ­
b l e s t r a i n s a f t e r 2 , U-D t r e a t m e n t , com pared w i t h u n t r e a t e d c h e c k s .
-31-
-------------. —S u s c e p t i b l e (2 r e p s
F i g u r e 6 . A v e ra g e r o o t g ro w th o f f o u r v i s u a l l y r a t e d s t r a i n s , two
r e l a t i v e l y s u s c e p t i b l e ( M .I I and CAN) an d two r e l a t i v e l y r e ­
s i s t a n t ( M .I I I and ND I ) , t r e a t e d w i t h 2 , U-D a t a r a t e o f
0 .5 I b / a c r e .
-
32 -
Shoot and Root Responses to G ibberellic Acid
I t w as s u g g e s t e d b y S h a f e r an d M onson (U2) t h a t g i b b e r e l l i c a c id
s h o u ld be i n v e s t i g a t e d f u r t h e r t o d e te r m in e p r a c t i c a l a s p e c t s o f t f i i s
c h e m ic a l, e s p e c i a l l y i n c o m b in a tio n w i t h h e r b i c i d e s .
The r e s p o n s e o f e a c h o f t h e n i n e l e a f y s p u rg e s t r a i n s t o g i b b e r ­
e llic
a c i d was s t u d i e d b y t r e a t i n g t h e s o i l i n e a c h p o t w i t h £ o m l o f a
100 ppm s o l u t i o n o f g i b b e r e l l i c a c i d .
The p h o to g r a p h s p r e s e n t e d i n
F i g u r e s 9 a n d 10 i n d i c a t e t h a t e a c h s t r a i n r e s p o n d e d t o t h e u s e o f t h i s
c h e m ic a l.
The tw o s t r a i n s t h a t a p p e a r e d t o b e m ost s t i m u l a t e d b y g ib ­
b e r e l l i c a c i d (COL and 'CM) w e re t h e same tw o t h a t a p p e a r e d t o b e more
s u s c e p t i b l e t o t h e k i l l i n g a c t i o n o f 2 , Ii-D ( s e e 2 , U-D r a t i n g s TABLE I ) .
The s t i m u l a t e d g ro w th o f p l a n t s from U s t r a i n s a r e com pared i n F i g u r e 10
w i t h two n o n - t r e a t e d p l a n t s .
Two s t r a i n s
(C M a n d ND I ) w h ic h w e re v i s u a l l y r a t e d a s b e in g r e l a ­
t i v e l y s u s c e p t i b l e and r e l a t i v e l y r e s i s t a n t w e re e s t a b l i s h e d i n s o i l f i l l e d p o t s a n d w ere I n d i v i d u a l l y s p r a y e d w i t h e i t h e r 5»00, 1000 o r 2000
ppm s o l u t i o n s o£ g i b b e r e l l i c a c i d a t a r a t e o f 80 g a l / a c r e .
tiv e
A ccum ula­
s h o o t m e a s u re m e n ts f o r b o t h t h e 'CAN a n d ND I s t r a i n s w e re r e c o r d e d
i n F ig u r e l l .
As i n t h e p r e v i o u s t e s t , t h o s e s t r a i n s w hose to p g ro w th
r e s p o n d e d m o st t o t h e a c t i o n o f 2 ,U -D , a l s o p r o d u c e d t h e l o n g e s t s h o o t
g r o w th .
The am ount o f g ro w th s t i m u l a t i o n fro m t h i s
f o lia g e tre a tm e n t
w as much l e s s t h a n t h a t r e s u l t i n g when t h e s o i l was t r e a t e d , b u t t h e s e
r e s u l t s a r e s i m i l a r t o t h o s e o b t a i n e d fro m s o i l t r e a t m e n t s w i t h g ib ­
b e r e l l i c a c id .
The root growth ch aracteristics were also studied in glass faced
-55-
G lass fa c e d boxes w ith w hite tap e t o show root c h a r a c t e r i s t i c s
Figure 7 • L eft i The p lan t on th e l e f t s id e o f th e box was
t r e a t e d w ith 0*5 I b /a c r e o f 2 , 4 - D . The p lan t on t h e r ig h t
i s a ch eck . (Each b la ck mark i n d i c a t e s 2 days o f growth
w ith black l i n e for date o f t r e a t m e n t . )
Figure 8 . R ig h ti The t a l l e r plant on the l e f t s id e was sprayed
w ith a 1000 ppm s o l u t i o n o f g i b b e r e l l i c a c id a t an 80 g a l /
acre r a t e . The p lan t on th e r i g h t s id e i s a check p la n t .
-54-
CHECK
CHECK
P ic t u r e s were taken one and o n e - n a if months a f t e r
t r e a t i n g tw o -in c h s h o o t s .
Figure 9- Above! Nine s t r a i n s and t h e i r r e l a t i v e growth
resp on se t o ^ > 0 ml o f a ICO ppm s o l u t i o n o f g i b b e r e l l i c
a c id a p p lie d as a s o i l tr e a t m e n t .
Figure 1 0 . Below i Two r e l a t i v e l y s u s c e p t i b l e p la n ts (COL and
CAN) and two r e l a t i v e l y r e s i s t a n t p la n ts (ND I and 3 . D . )
e x h ib it d i f f e r e n t l e v e l s o f resp on se when t r e a t e d w ith
g i b b e r e l l i c a c i d . The checks are untreated and rep re se n t
normal growth.
-35-
-----T r e a t e d (CAN)
_ - T r e a t e d (ND I )
___ U n t r e a t e d (CAN) c h e c k
___ U n t r e a t e d (ND I ) c h e c k
DAYS AFTER TREATMENT
F i g u r e 1 1 . The i n c r e a s e d s h o o t g ro w th o f tw o s t r a i n s o f l e a f y s p u rg e
when f o l i a r a p p l i c a t i o n s o f g i b b e r e l l i c a c i d w e re a p p l i e d .
(A v e ra g e o f U t r e a t e d and 2 u n t r e a t e d r e p l i c a t i o n s )
—
36boxes su b se q u e n t to g i b b e r e ll ic a c id tre a tm e n ts .
M e a su re m e n ts w ere
made on t h e r a t e o f r o o t g ro w th f o r t h e f i r s t few d a y s , a f t e r w h ich
l a t e r a l r o o t d e v e lo p m e n t becam e s o e x t e n s i v e on t h e g i b b e r e l l i c a c i d
t r e a t e d p l a n t s t h a t i t was n o t p o s s i b l e t o make a c c u r a t e q u a n t i t a t i v e
m e a s u r e m e n ts .
The r a t e o f g ro w th p e r r o o t was n o t n o t i c e a b l y a f f e c t e d
b y t h e t r e a t m e n t , b u t a s shown i n F i g u r e 8 , r o o t num bers w e re i n c r e a s e d
when g i b b e r e l l i c a c i d w as a p p l i e d .
I n one t e s t g i b b e r e l l i c a c i d was a p p l i e d 3 d a y s b e f o r e t r e a t i n g
w i t h 2 , U-D a t a r a t e o f 0 .5 I b / a c r e .
"While o n l y s i x p l a n t s w ere t r e a t e d
i n t h i s w ay, t h e r e was no i n d i c a t i o n t h a t g i b b e r e l l i c a c i d i n c r e a s e d '
t h e e f f e c t i v e n e s s o f 2 ,U -D .
D i f f e r e n c e s i n M o rp h o lo g y
l e a f V a ria tio n s
D i f f e r e n c e s w ere o b s e r v e d i n t h e s i z e and s h a p e o f t h e l e a v e s from
th e n in e s t r a i n s s tu d ie d .
The two s t r a i n s p i c t u r e d i n F i g u r e I i n d i ­
c a t e some o f t h e s e d i f f e r e n c e s .
M ic r o s c o p ic d i f f e r e n c e s , s u c h a s th e
n a t u r e a n d t h i c k n e s s o f t h e c u t i c l e and t h e num ber o f s to m a ta h a v e b e e n
c o n s id e re d t o b e im p o rta n t i n th e s e l e c t i v e a c tio n o f h e r b i c id e s .
C ro ss s e c t i o n s w e re t a k e n fro m l e a f y s p u r g e l e a v e s and when m ounted
i n t h e m an n er d e s c r i b e d b y J o h a n s e n (2 9 ) r e v e a l e d a c u t i c l e t h a t was so
t h i n an d u n e v e n t h a t m e a su re m e n ts w ere h o t p o s s i b l e .
The x y le n e u s e d
i n c l e a r i n g t h e p a ro w a x fro m t h e l e a f t i s s u e a t t h e t im e o f s t a i n i n g
was s u s p e c t e d a s b e i n g r e s p o n s i b l e f o r re m o v in g some o f t h e c u t i c l e .
An a l t e r n a t e m eth o d o f h a n d s l i c i n g t h i n l e a f s e c t i o n s w i t h a r a z o r
-37b l a d e was m ore s a t i s f a c t o r y .
shown i n F i g u r e 1 2 .
A p h o to m ic r o g r a p h o f one s u c h s e c t i o n i s
The c u t i c l e t h i c k n e s s on many l e a f s u r f a c e s was
o n l y 2 -3 m ic r o n s , and some d i f f i c u l t y was e n c o u n te r e d i n g e t t i n g e x a c t
m e a s u re m e n ts .
M e asu re m e n ts o f t h e c u t i c l e t h i c k n e s s w e re made on r e p ­
r e s e n t a t i v e l e a v e s fro m e a c h s t r a i n .
The r e s u l t s a r e p r e s e n t e d i n
TABLE I I .
The n a t u r e an d t h i c k n e s s o f t h e c u t i c l e on a l l s t r a i n s was s i m i l a r
on t h e u p p e r e p i d e r m i s .
t h i c k n e s s was n o t e d .
On t h e lo w e r e p id e r m is some v a r i a b i l i t y i n
T h e re a p p e a r s t o b e l i t t l e
d iffe re n c e i n c u tic le
t h i c k n e s s on t h e n i n e s t r a i n s i n v e s t i g a t e d .
S to m a ta c o u n ts w e re made on s e v e r a l l e a v e s fro m e a c h o f t h e n in e
s tr a in s o f le a f y sp u rg e .
•
I n d i v i d u a l r e a d i n g s a r e g iv e n i n APPENDIX
TABLE I I I , w h i l e a v e r a g e r e s u l t s a r e p r e s e n t e d i n TABLE I I I .
The low ­
e s t a v e r a g e num ber o f s to m a ta w as fo u n d on t h e s t r a i n fro m C o lo ra d o ,
w h i l e t h e h i g h e s t num ber w as r e c o r d e d f o r MD I I .
D i f f e r e n c e s b e tw e e n
s t r a i n s w ere fo u n d t o b e s i g n i f i c a n t a t t h e 1% l e v e l o f p r o b a b i l i t y .
A bout o n e - t h i r d m ore s to m a ta w e re fo u n d on t h e lo w e r s u r f a c e t h a n
on t h e u p p e r .
T h e re w e re s i g n i f i c a n t l y f e w e r s to m a ta f o u n d on t h e b a s e
o f t h e l e a f t h a n a t e i t h e r o f t h e o t h e r l o c a t i o n s e x a m in e d , b u t t h i s
d i f f e r e n c e w as n o t c o n s t a n t f o r a l l s t r a i n s .
I f s to m a ta w ere s e r v i n g a s t h e p r i n c i p a l a v e n u e s f o r e n t r y o f 2,Ll-D
i n t o t h e l e a f y s p u rg e l e a v e s , t h e n t h e s t r a i n w i t h t h e l a r g e s t num ber
o f s to m a ta on t h e u p p e r s u r f a c e s h o u ld h a v e b e e n i n j u r e d m o st e x t e n s i v e ­
l y b y 2 , H-D.
A c t u a l l y no t r e n d c o u ld be d i s c o v e r e d r e l a t i n g t h e num ber
o f s to m a ta on e i t h e r s u r f a c e o r t o t h e t o t a l num ber o f s to m a ta on b o t h
-38-
table
II.
C u t i c l e t h i c k n e s s m e a s u re d i n m ic ro n s on l e a f s u r ­
f a c e s o f n i n e s t r a i n s o f l e a f y s p u r g e .*
^
L eaf su rfa c e
»
•
" 'U p p e r
e p id e r m i s
"" Low er'
e p id e r m is
S .D .
3
3
£
M .I I I
2
3
5
ND I
2
2
h
ND I I
3
3
5
IDA
2
2
OOL
2
h
5
M .I
3
3
Ii
CAN
2
3
6
M .II
2
2
U
S tra in
so u rc e
U n d e r s id e o f
l e a f m id -rib
U
.
A v e ra g e o f t h r e e r e p l i c a t i o n s on th r e e - m o n th o l d p l a n t s .
I
-39-
Figure 1 2 . A c r o s s s e c t i o n o f a l e a f y spurge l e a f , n ote th e
t h ic k e r c u t i c l e on th e underside o f th e l e a f m id - r i b .
(M a g n ific a tio n c a . 180X)
Figure I ) . The root system s o f t h r e e d i f f e r e n t s t r a i n s o f
l e a f y spurge which were taken from 18 in ch deep green­
house cans and washed.
TABLE I I I - .
A v e ra g e n u m b er' o f s to m a ta c o u n ted " on t h e u p p e r and lo w e r
l e a f s u r f a c e s o f n i n e l e a f y s p u rg e s t r a i n s . ^
A v e ra g e num ber o f s to m a ta on t h e s u r f a c e s o f e a c h s t r a i n .
M .I I I M .I I
CAN
ND.' I I
UPPER
B a se
M .I
IDA
1 3 .0
1 5 .3
1 3 .0
1 2 .0
1 2 .3
M id d le'
1 6 .6
1 L.6
Ilu O
1 7 .3
T ip
1 2 .0
13 o3 ■1 5 .0
A ve.
llw 9
1U.U
B a se
2 2 .3
M id d le
S .D .
ND I
COL
A ve.
1 1 ,3
8 .3
1 3 .6
9 .6
1 2 .0
l i t .3
1 3 .6
1 3 .0
1 6 .0
1 1 .6
lit.6
1 8 .0
lit. 6
1 8 .0
1 1 .6
1 1 .3 . r u o
.lit. 2
Ilu O
1 5 .8
1 3 .7
lit.3
1 1 .0
1 3 .6
1 0 .7
1 3 .6
1 6 .0
1 8 .6
2 5 .6
1 3 .6
1 5 .3
2 0 .3
2 1 .6
1 3 .3
1 8 .8
2 0 .0
1 9 .0
2 0 ,0
2 3 .3
lit.6
1 9 .0
2 2 .6
2 1 .6
lit.6
1 9 .lt
T ip
1 9 .3
1 7 .6
1 9 .3
2 5 .0
Ilu O . 2 IuO
2 7 .3
2 3 .7
1 6 .3
2 0 .7
Ave.-
2 1 .5
1 7 .5
1 9 .3
2 1 .6
lit. I
2 3 , It
2 2 .3
ItU 7
1 9 i6
1 5 .9
1 6 .6
2 0 .2 , 1 3 .9
1 6 .8 . 1 7 .2
1 7 ,9
1 2 .7
1 6 .6
LOWER
19 oIt
UPPER-LOWER
A ve.
1 8 .2
** S to m a ta c o u n ts w ere made from an a r e a .1 1
th re e d if f e r e n t p la n ts o f each s tr a in .
Itirn^
, -
on e a c h l e a f s u r f a c e o f
-la s u r f a c e s t o 2 , Ii-D i n j u r y .
The num ber o f s to m a ta p e r s q u a r e m i l l i m e t e r on b o t h l e a f s u r f a c e 's
a re p r e s e n te d g r a p h ic a lly i n F ig u re l l i .
R oot C h a r a c te r is tic s
,
.
The r o o t s y s te m s bin t h e v a r i o u s s t r a i n s o f l e a f y s p u r g e w ere ob­
s e r v e d when t h e y w e re b e i n g p r e p a r e d f o r p r o p a g a t i n g new p l a n t s .
f e r e n c e s i n l e n g t h and t e x t u r e o f t h e r o o t s y s te m s w ere n o t e d .
D if­
The
m o st n o t i c e a b l e d i f f e r e n c e o b s e rv e d was i n t h e 'COL s t r a i n w h ic h h a d a r e l a t i v e l y s h a ll o w r o o t s y s te m w i t h many l a t e r a l r o o t s .
T h is l a t e r a l
r o o t d e v e lo p m e n t was e s p e c i a l l y n o t i c e a b l e when o b s e r v i n g r o o t c h a r ­
a c t e r i s t i c s w h ile p l a n t s w ere g ro w in g i n g l a s s - s i d e d b o x e s .
M ost
s t r a i n s e x h i b i t e d a r e l a t i v e l y d e e p r o o t s y s te m i n c o m p a ris o n t o t h e
COL s t r a i n ,
t h e ND I I s t r a i n d e v e lo p e d lo n g r o o t s w ith m o st o f them
b e in g q u ite c o a rs e .
Some o f t h e s e d i f f e r e n c e s a r e i l l u s t r a t e d i n F i g ­
u re 13.
D orm ancy
A l l l e a f y s p u r g e s t r a i n s s t u d i e d e x h i b i t e d a s e m i-d o rm a n c y d u r in g
th e . f a l l a n d e a r l y w i n t e r m o n th s ^
Two m eth o d s w ere u s e d t o overcom e
t h i s s lo w t y p e o f g ro w th s o e x p e r i m e n t a l w o rk c o u ld b e c o n d u c te d
th r o u g h o u t t h e y e a r .
By i n c r e a s i n g t h e l i g h t p e r i o d t o l l i h o u r s some i n c r e a s e d g ro w th
was o b s e r v e d .
H ow ever5 g ro w th was s t i l l l e s s t h a n t h a t d u r i n g s p r i n g
and summer m o n th s .
Some i n c r e a s e d g ro w th r e s u l t e d fro m s t o r i n g d o rm an t r o o t s i n t h e
-142-
T o le r a n c e
ra tin g "
S tra in
The num ber o f s to m a ta p e r mm'
ND I
ND I I
3
U pper
ZZl
Lower
F ig u re l b .
A verage num ber o f s to m a ta on t h e u p p e r and lo w e r l e a f s u r ­
f a c e s o f n in e s t r a i n s o f l e a f y s p u rg e .
*F rom TABLE I .
* * C oun ts w ere t a k e n fro m t h e t i p , m i d - s e c t i o n and b a s a l p o r t i o n s
o f m a tu re l e a v e s .
At l e a s t t h r e e d i f f e r e n t p l a n t s fro m e a c h
s t r a i n w e re i n v e s t i g a t e d f o r f i n a l d e t e r m i n a t i o n s .
-h3r e f r i g e r a t o r f o r fro m I t o 3 m onths p r i o r t o p l a n t i n g i n p o t s i n t h e
g reen h o u se.
H ow ever, r e s u l t s fro m t h i s m eth o d w ere e r r a t i c .
I
DISCUSSION
Some i n v e s t i g a t o r s h a v e s h o w t h a t v a r i a b i l i t y e x i s t s w i t h i n some
w eedy s p e c i e s ( 8 , 2 6 , 5>0),
D i f f e r e n c e s w i t h i n a g iv e n s p e c i e s c o u ld
e x p l a i n why e r r a t i c r e s u l t s h a v e b e e n r e p o r t e d i n c o n t r o l l i n g d i f f i c u l t
w eeds.
I n t h i s s t u d y l e a f y s p u rg e r o o t s w ere c o l l e c t e d fro m e i g h t l o c a ­
t i o n s i n t h e U n ite d S t a t e s and one i n
C anada.
P l a n t s w ere v e g e t a t i v e I y
re p ro d u c e d i n th e g ree n h o u se f o r a l l s t u d i e s .
The p l a n t s fro m e a c h l o ­
c a tio n a re r e f e r r e d to as s t r a i n s .
I n s t u d y i n g t h e g ro w th c h a r a c t e r i s t i c s o f t h e v a r i o u s s t r a i n s ,
d i f f e r e n c e s w e re n o t e d i n t h e s i z e a n d s h a p e s o f l e a v e s .
The s t r a i n s
c o l l e c t e d a p p e a r t o f i t t h e b o t a n i c a l d e s c r i p t i o n f o r E u p h o r b ia e s u l a ,
w i t h t h e p o s s i b l e e x c e p t i o n o f t h e C a n a d ia n c o l l e c t i o n .
The l e a v e s on
t h e C a n a d ia n s t r a i n a r e o f a l i n e a r n a t u r e , t h e p l a n t t e n d s t o b e s h o r t ­
e r a t m a t u r i t y and i t p r o d u c e s f lo w e r s m ore f r e q u e n t l y a n d o v e r l o n g e r
p e rio d s th a n o th e r s t r a i n s .
T h e se f e a t u r e s s u g g e s t t h a t i t m ig h t b e an E . e s u l a an d E . ■c y p a r i s s ia s
c ro ss.
M oore an d L in d s a y ( 35) l i s t e d t h e s e c h a r a c t e r i s t i c s i n t h e
i d e n t i f i c a t i o n o f a c r o s s b e tw e e n t h e s e tw o s p e c i e s .
W ith o u t c y t o l o g i c a l e v id e n c e a s . t o t h e num ber o f chrom osom es, i t
w o u ld b e h a r d t o g iv e a d e f i n i t e a n s w e r r e g a r d i n g t h e c o r r e c t s p e c i e s
name o f t h e s t r a i n fro m C a n a d a .
M oore (3U) s t u d i e d IU d i f f e r e n t c o l l e c ­
t i o n s fro m O n t a r i o a n d S a s k a tc h e w a n an d r e p o r t e d them a l l t o h a v e 2n=60
chrom osom e n u m b e rs .
E u p h o r b ia c y p a r i s s i a s i s r e p o r t e d ( 35 ) t o h a v e UO
chrom osom es i n t h e t e t r a p l o i d c o n d i t i o n .
H y b r id s b e tw e e n t h e two s p e c i e s
w o u ld h a v e a 2n=5>0 chrom osom e n u m b er.
The h e r b i c i d e 2 ,^ -D was u s e d t o d e te r m in e w h e th e r d i f f e r e n t s t r a i n s
o f l e a f y sp u rg e w i l l e x h ib i t d i f f e r e n t l e v e l s o f to le r a n c e t o t h i s
c h e m ic a l.
P l a n t s fro m a l l s t r a i n s w e re s e l e c t e d f o r u n i f o r m i t y and
s p r a y e d w i t h 0 . 25 , 0 .5 a n d 1 . 0 pound p e r a c r e r a t e s . . .
D if f e r e n t s t r a i n s e x h ib ite d v a ry in g le v e ls o f to le r a n c e t o th e
h e r b i c i d e a s m e a s u re d b y t o p g ro w th c o n t r o l .
D i f f e r e n c e s w gre n o t as
p ro n o u n c e d when t h e r a t e s o f 2 , U-D w e re i n c r e a s e d , s u g g e s t i n g t h a t t h e
s t r a i n s h a v e a n a rr o w r a n g e o f d i f f e r e n t i a l t o l e r a n c e t o 2 ,U -D .
B o th v i s u a l an d w e ig h t m e a s u re m e n ts w ere u s e d t o d e te r m in e r e l a ­
tiv e to le ra n c e o f each s t r a i n .
"When t h e d a t a fro m w e ig h t'm e a s u r e m e n ts
was s t a t i s t i c a l l y a n a l y z e d , t h e s t r a i n s w ere n o t fo u n d t o b e s i g n i f i ­
c a n tly d if f e r e n t.
The r a t e o f 2 , U-D was n o t h i g h eno u g h t o k i l l a p y
p l a n t s , so i t i s f e l t t h a t o t h e r t e s t s
s h o u ld b e c o n d u c te d a t h i g h e r
r a t e s o r a t a tim e o f t h e y e a r when g ro w th i s m ore r a p i d a n d t h e h e r b i ­
c id e c a n b e m ore e f f e c t i v e .
Some k i l l i n g a c t i o n s h o u ld b e e x p r e s s e d
b e f o r e an a c c u r a t e m e a s u re o f a n y d i f f e r e n t i a l k i l l c a n b e e v a l u a t e d .
Some v a r i a b i l i t y was a l s o n o te d w i t h i n s t r a i n s .
T h is c o u ld h a v e
r e s u l t e d fro m v a r i a b i l i t y i n t h e o r i g i n a l r o o t s c o l l e c t e d .
m ethod o f c o l l e c t i n g t h e r o o t s i s n o t know n, b u t i t i s
The e x a c t
assum ed t h a t t h e y
w e re a l l g a t h e r e d fro m one s m a l l a r e a a n d w o u ld m ost l i k e l y h a v e r e ­
s u l t e d fro m an o r i g i n a l i n f e s t a t i o n fro m one s e e d .
V a r i a b i l i t y w ith in
c lo n e s was a l s o n o t e d b y B u c h h o ltz ( 8 ) when q u a c k g r a s s was t r e a t e d w i t h
d a la p o n .
I t was' s u g g e s t e d b y A sh to n ( I ) t h a t g i b b e r e I l i c a c i d may b e u s e f u l
!
i n s tim u la tin g h e r b ic id e t r a n s lo c a ti o n w ith in th e p l a n t ,
In t h i s s tu d y
when g i b b e r e l l i c a c i d was a p p l i e d b o t h t o t h e f o l i a g e a n d a s a s o i l
t r e a t m e n t 5 .p l a n t s o f a l l s t r a i n s r e s p o n d e d w i t h i n c r e a s e d s h o o t g ro w th .
The p l a n t s h o o ts w h ic h a p p e a r e d t o b e m ost s u s c e p t i b l e t o t h e k i l l i n g
a c t i o n o f 2 , L-D w e re t h e m ost s t i m u l a t e d w i t h g i b b e r e l l i c a c i d .
T h is
w o u ld seem t o i n d i c a t e t h a t o t h e r p l a n t g ro w th r e g u l a t o r s may, c a u s e
d i f f e r e n t r e s p o n s e s on t h e s e s t r a i n s .
R o o t g ro w th was a l s o a f f e c t e d b y g i b b e r e l l i c a c i d .
When i t was
'
a p p l i e d as a 1000 ppm s o l u t i o n a t a r a t e o f 80 g a l / a c r e , m ore l a t e r a l
r o o t d e v e lo p m e n t was n o t e d .
In v e s tig a to rs
( 2 5 s h2) h a v e p r e v i o u s l y r e ­
p o r t e d t h a t g i b b e r e l l i c a c i d w i l l s t i m u l a t e t h e d e v e lo p m e n t o f more
b u d s and s h o o t s .
I t h a s b e e n s u g g e s t e d ( 1 6 / 17«, 28) t h a t d i f f e r e n c e s i n l e a f mor­
p h o lo g y m ig h t a c c o u n t f o r v a r i a t i o n s i n t h e am ount o f h e r b i c i d e t h a t
w o u ld p e n e t r a t e o r b e a b s o r b e d b y a t r e a t e d p l a n t .
S to m a ta and c u t i c l e
h a v e b e e n show n ( 1 6 ) t o a f f e c t t h e e n t r y o f c h e m ic a ls i n t o p l a n t l e a v e s .
B o th w e re e x a m in ed t o s e e i f t h e y m ig h t e x p l a i n t h e v i s u a l d i f f e r e n t i a l
r e s p o n s e o b t a i n e d w i t h 2 , L-D on t h e s e l e a f y s p u rg e s t r a i n s .
Some d i f f i ­
c u l t y was e n c o u n te r e d i n m e a s u r in g c u t i c l e t h i c k n e s s j h o w e v e rs t h e r e was
little
d i f f e r e n c e o b s e r v e d b e tw e e n s t r a i n s ^ e i t h e r i n n a t u r e o r amount
o f c u t i c l e on t h e u p p e r e p i d e r m i s .
W h ile c u t i c l e t h i c k n e s s i s
u n d o u b t­
e d l y a f f e c t e d b y c l i m a t i c f a c t o r s and a g r e a t e r c u t i n d e p o s i t w ould
p r o b a b l y h a v e b e e n fo u n d i f p l a n t s h a d b e e n ex am in ed t h a t w e re g ro w in g
o u t s i d e t h e g r e e n h o u s e , i t i s u n l i k e l y t h a l t h e s t r a i n s w o u ld h a v e shown
-k l-
any g r e a te r v a r i a b i l i t y i n t h i s c h a r a c te r is t ic .
T h e re a p p e a r e d t o b e no r e l a t i o n s h i p b e tw e e n e i t h e r t h e num ber o f
s to m a ta on thej l e a f s u r f a c e s o f l e a f y s p u rg e o r t h e am ount o f c u t i c l e
a n d t h e 2 , It-D- r e s p o n s e o b t a i n e d .
■ SUMMARY
1.
L e a f y s p u r g e r o o t s e c t i o n s w ere c o l l e c t e d fro m s e v e r a l s t a t e s and
one p r o v in c e i n C an ad a.
a s tra in .
E ach c o l l e c t i o n s o u r c e was d e s i g n a t e d a s
P l a n t s w e re v e g e t a t i v e I y p r o p a g a t e d f o r a l l - t e s t s .
2.
S t r a i n s d i f f e r e d i n l e a f an d s h o o t m o rp h o lo g y .
■3*
A l l s t r a i n s e x c e p t one w e re c o n s i d e r e d t o b e lo n g t o t h e sam e s p e c ie s ^
U.'
V is u a l r a t i n g o f t o p - k i l l i n d ic a te d d i f f e r e n t i a l - to le r a n c e o f
s t r a i n s t o 2>U-D t r e a t m e n t s .
3«
B o th f o l i a g e a n d s o i l t r e a t m e n t s o f g i b b e r e l l i c a c i d c a u s e d i n ­
c r e a s e d s h o o t g ro w th .
6.
P l a n t s w h ic h a p p e a r e d t o b e m ore s u s c e p t i b l e to - t h e k i l l i n g a c t i o n
o f 2 , Ij-D u s u a l l y show ed g r e a t e s t r e s p o n s e t o g i b b e r e l l i c a c i d .
7.
Vihen g i b b e r e l l i c ' a c i d was u s e d a s a p r e t r e a t m e n t f o r 2 , U-D a p p l i c a ­
t i o n s , no a p p a r e n t a d v a n ta g e was r e a l i z e d .
8.
No d i f f e r e n c e i n t h e am ount o f l e a f c u t i c l e was f o u n d b e tw e e n
■ s tra in s »
9.
S to m a ta num bers on d i f f e r e n t s t r a i n s w ere fo u n d t o f l u c t u a t e ' b o th
w i t h i n and b e tw e e n s p e c i e s .
10.
N e i t h e r t h e c u t i c l e t h i c k n e s s n o r t h e num ber o f s to m a ta on l e a f
s u r f a c e s a p p e a r e d t o b e i m p o r ta n t i n d e te r m i n in g t h e r e s p o n s e o f
s tr a in s to
2,U -D .
11.
One s t r a i n
(COL) show ed a d i f f e r e n t t y p e o f r o o t s y s te m . .
12.
V i n t e r d o rm a n c y i s
te m p e ra tu re .
c o n t r o l l e d b y l e n g t h o f t h e l i g h t p e r i o d and b y
APPENDIX
APPENDIX TABLE I .
S tra in so u rc e
I r i 3 i v i d u a l r a t i n g s oh n i n e s t r a i n s o f l e a f y s p u rg e
t r e a t e d w i t h t h r e e r a t e s o f 2 ,^ - D .
R a te o f 2 . -i-D and r a t i n e * f o r e a c h r e p l i c a t i o n
■
■ '0 .5 'lb /A
0 .2 5 I b /A
1 .0 Ib /A
-Re OS.
R e p lic a tio n s
R eps.
S .D ,
3
M .I I I
3
2
2
2
3
I
I
I
2
2
3
3
3
I
2
2
2
ND I
I
I
I
I
I
h
.3
6
6
ND I I
Ir
U
k
Ir
h
.6
8
3 .
3
IDA
6
6
8
8
. 8
5
5
U
U
OOL
5
5
7
7
7
7
9
5
'5
■ M .I
8
8
.5
, 5
5
h
8
8
'CAN
7
7 :
9
9
9
8
6
7
7
M .I I
9
9
6
6
6
9
7'
9
9
,
: , 2-
T r e a t e d p l a n t s ' I n e a c h r e p l i c a t i o n '’a r e r a t e d fro m I t o 9 w i t h I
r e p r e s e n t i n g t h e m o st t o l e r a n t o r r e s i s t a n t s t r a i n .
APPENDIX TABLE T I .
S o u rc e
T lie 'w e ig h t' b e f o r e a n d " a f t e r t r e a t m e n t "an d t h e
■ p e r c e n t a g e c h a n g e ' i n ' w eig h t" o f l e a f y " sp u rg e s h o o ts
t r e a t e d w i t h two 0 e2£ l b / a c r e f a t e s o f 2 ^U-D6
R e p lic a tio n # 1
In itia l*
F i n a i ti'" %
R e p l i c a t i o n #2
I n i t i a l F in a l
■%
R e p l i c a t i o n §3
I n i t i a l F in a l %
M .I I I
390
821
2 1 0 .5
689
1236
1 7 9 .U
52U
828
158.0
COL
205
559
272.7,
555
975
1 7 5 .7
650 667
102.6
IDA
265
• U51
170,2
261
393
150.6
530
868
1 6 3 ,8
CAN
U5i
626
1 3 8 .8
U22
625
1U8.1
590
607
102.9
M6I
353
'651
l8U.il-
U23
66U
157.0.
U5i 677
150.1
ND I
325
558
171.7
371
77U
2 0 8 .6
U03 85U
211.9.
ND I I
328
U80
1U 6.3
3Uo
537
157.9
393
523
133.1
M6I I
228
■U81
2 Ilo O
36U
6 07
166.8
369
256
S 6D 6
305
' 367
120.3
266
570
21U.3
357 721 .
69. U
202.0
^ T h e 'w e ig h t i n m i l l i g r a m s o f a s i n g l e s h o o t h a r v e s t e d t h e d a y o f
t r e a tm e n t'.' "
'
'
"
'“""A verage w e ig h t i n m il li g r a m s o f tw o s h o o ts U5 d a y s a f t e r t r e a t m e n t .
-52-
AFPENDIX TABLE I I I .
The ra w d a t a f o r u p p e r and lo w e r s to m a ta c o u n ts
on l e a f y s p u rg e s t r a i n s .
UPPER LEAF SURFACE COUNTS'
S tra in
B a se
A ve„ .
M id d le
A ve.-
T ip
A ve,
M .I I I
Ih 13 12*
1 3 .0
16 18 16
1 6 ,6
15 18 12
1 5 .0
MeI I
16 18 12
1 5 .3
12 18 I li
U i e6
10 U i 16
1 3 ,3
CAN
10 18 11
1 3 .0
16 12 IL
lll.O
U i 16 15
1 5 .0
ND I I
12 I li 10
1 2 .0
18 22 12
1 7 .3
18 16 20
1 8 .0
•M»I
10 15 12
1 2 .3
15 16 12
H i. 3
12 18 I li
111. 6
IDA-
111 12
8
1 1 .3
10 16 15
1 3 .6
20 20 111
1 8 .0
S eDe
8 10
7
8 .3
U i i o 15
1 3 .0
9 16
1 1 .6
ND I
12 i l l 15
1 3 .6
18 Ui 16
1 6 .0
8 16 10
1 1 .3
COL
8 10 11
9 .6
13 12 10
1 1 .6
11 12 10
1 1 .0
LOWER LEAF SURFA7CE COUNTS
S tra in
B ase
Ave.
•
‘10
-
M id d le
Ave e
T ip
Ave o
M .II I
28 26 22
2 5 .3
22 20 18
2 0 .0
22 19 17
1 9 .3
M .I I
16 18 I li
1 6 .0
111 19 2l|
1 9 .0
111 2 l| 15
1 7 .6
CAN
H i 18 2 Ii
1 8 .6
18 16 26
2 0 .0
18 18 22
ND I I
26 26 25
2 5 .6
2li 20 26
2 3 .3
26 25 2li
2 5 .0
MeI
12 12 17
1 3 .6
15 13 16
lli.6
16 12 I li
lll.O
IDA
111 16 16
1 5 .3
15 18 2li
1 9 .0
16 30 26
2 l|.0
S .D .
17 28 16
2 0 .3
16 28 2 l|
2 2 .6
23 32 27
2 7 .3
ND I
18 25 22
2 1 .6
25 22 18
2 1 .6
25 16 30
2 3 .7
COL
12 '13 15
1 3 .3
10 18 16
1 1 1 .6
13 16 20
1 6 .3
* Num bers r e p r e s e n t i n d i v i d u a l r e a d i n g s from a n a r e a .1 1
'
1 9 .3
.
APPENDIX TABLE IV .
S o u rce o f v a r i a t i o n
A n a l y s i s o f v a r i a n c e f o r s to m a ta d i s t r i b u t i o n on
l e a f s u rf a c e s o f n in e s t r a i n s o f l e a f y sp u rg e .
D .E .
S .S .
M .S .
• F - v a lu e
I
1 A 8 8 .1 6
' ljli.8 8 .1 6
■8
7 2 3 .2 6
9 0 . Ul
3 7 .1 0 * *
R e a d in g s
2
1 7 2 .7 9
8 6 .3 9
32. U f
L o c a ti o n s on l e a f
2
1 1 8 .3 8
2 9 .1 9
2 U .29*
S u rfa c e X S tr a in
8 '
1 6 3 .8 0
2 7 .9 7
2 3 .7 9 * *
S u r f a c e X L o c a ti o n
2
3 0 .2 3
1 2 .1 2
6 .2 0
L o c a ti o n X S t r a i n
16
2 2 0 .1 9
1 3 .7 6
2 .6 2 * *
L X S X S
16
8 9 7 .1 9
2 6 .0 7
2 3 . O lii^
E rro r
106
2 2 8 .3 3
T o ta l
l6 l
W 3 7 2 .3 3
S u rfa c e s
S tra in s
^ S i g n i f i c a n t a t E> p e r c e n t l e v e l
^ 'S i g n i f i c a n t a t I p e r c e n t l e v e l
;
2.U 37
6 1 0 .6 2 ^
LITERATURE CITED
1«
A s h to n , Fe Mo E f f e c t o f g i b b e r e l l i c a c i d oh a b s o r p t i o n , ' t r a n s l o ­
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7sU 36-U U l. 1 9 5 9 .
2,
B a k e r , L . 0 . E f f e c t o f c e r t a i n c l i m a t i c a n d s o i l f a c t o r s ir}
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1 9 6 1 . - (M im e o g ra p h e d ).
3.
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Ue
B a th o ," G .
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5.
B e l l u e , M. Ke
6.
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7.
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8.
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9.
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1936,
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J o u r . N, I . B o t ,
10.
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~
55
>
“
liu
C r a f t s , Ao S . H e r b i c i d e s , t h e i r a b s o r p t i o n and t r a n s I o c a t i o n e
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I^ .
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17•
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;
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1920.
U5e
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U6.
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U8.
W e a v e r,* R . J . ’ a n d D eR dse, H .vR l A b s o r p tio n a n d 't r a n s l o c a t i o n o f
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h9>
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