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A STUDY OF THE EFFECTS OF WATER  AND CUTTING ON 
SEED PRODUCTION OF VERANO STYLO 
( S t y l o san t h e s  hama t a ) AND S IRATRO 
(Macrop t i l i um a tropurpureum )  
a thesis  presented in  partial fulfilment of  
the requirements for  the d egree of  Doctor 
o f  Philosophy at Mas sey University , 
Palmerston North , New Z ealand . 
PHANNA WAIKAKUL 
. 1983 
DEDICATED TO MY FATHER 
i 
ABSTRACT 
Tropical  pasture legume seed production in the North-east  
of  Thai land first  began in the early 1 9 7 0 ' s .  StyZosanthes hamata 
cv . Verano and MacroptiZiwn atropurpurewn cv . S i�atro were two 
o f  the forage l egumes proposed to fill  the requirement for 
improved pastures in thi s  region of Thailand . Thi s  s tudy 
was initiated to provide information on the effects of  water 
s tres s, s tage of plant development at the time of cutting 
and cutting intensi ty on seed production of these  two 
tropical  forage legumes , in the field at Khon Kaen , Tha i land . 
A second and more  intens ive s tudy on the reaction of  
Verano s tylo  to water s tress , and stage and intens ity of  
cutting was carried out to  provide a better understanding of  
pos s ible  p lant adaptation and the contribution o f  p lant 
components to seed yield of  thi s  s pecies  under control led 
environment conditions at the D.S . I.R . , Pa lmers ton North , 
New Z ealand . 
Initia l ly , fie ld experiments  were carried out in  two 
different s easons , ( dry season and wet season ) . The dry 
s eason experiment s tudied the e ffects of  irrigation , non­
irrigation , and cutting on s eed yield . In the wet season 
field experiment only the effect o f  cutting was s tudied ip 
both Verano sty lo and S iratro . The results from the dry 
season s tudy showed that species  are respons ive to irrigation . 
Irrigated plants produced about 2 5 %  more seed yield than non­
i rrigated plants in Verano stylo  but only about 1 0 %  more  in  
S iratro . The  response  of  the plants  to  cutting was  variable  
depending on the s tage and intens ity of  cutting . Light 
cutting at  either the vegetative or floral initiation s tages 
gave higher  seed yields than uncut plants in  Verano s ty lo ,  
while  in S iratro all  cut plants gave higher seed y ields  than 
uncut plants . Planting Verano sty lo or Siratro in  the wet 
s eason resulted in plants taking  longer to reach the repro­
ductive s tage than in the dry s eason . This  protracted 
vegetative s tage resulted in bigger plants and more s i tes  
for  s eedheads . I n  stylo  both cut and uncut plants gave 
h igher seed yields than those  obtained in the dry s eason 
ii  
planting , whi le in  Siratro plants  heavily cut at  the 
vegetative s tage gave the highest  seed yield . S i ratro plants 
grown in the wet s eason tended to produce strong vegetative 
growth and good inflorescence development . However , seed 
yield was l ower because of  poor pod development and low 
numbers o f  s eeds per pod . 
The s econd experiment on Verano s tylo was carried out 
under controlled environment conditions des igned to s imulate 
as closely  as  pos s ible  the d i fferent growing seasons  
previous ly used in the field . The results confirmed that 
water plays an important role in increasing s eed y ield in 
both cut and uncut plants , and e specially in cut plants  
provided they received high water levels  throughout the 
growing period . Water stress  appeared to change plant 
s tructure , both vegetative and reproductive growth being 
greatly reduced during the s tress  period . Water also  had 
an effect on the number of  s i te s  for seedhead formation and 
the contribution to seed yield . In plants which were  water 
s tressed from about 30 days a fter sowing (vegetative s tage ) 
both cut and uncut plants remained smal l  resulting in  low 
branch numbers , shorter branches  and fewer s ites  for seed­
head development . Water s tres s  applied following peak 
f lowering ( 5 5  days after sowing)  also  reduced seed yield , 
compared with the yield from plants receiving water throughout 
the period of seed development . The maximum yield  obtained 
varied from 1 . 2- 9 . 3  grams per plant between the three water 
treatments . 
Studies  on the contribution to  seed yield from each 
branch order and s eedhead position indicated that  in  both 
cut and uncut plants most  of the seed yield came from 
secondary branches  ( 6 0- 7 5 % )  . The contribution to  s eed 
y ield , however ,  was different between water treatments . 
I n  early s tressed plants s eed yield was apportioned almost  
equally between primary and s econdary branches . However in 
p lants which had been placed under water s tres s  at  peak 
f lowering , the seed y ield obtained from primary branches 
was  only half  that produced from secondary branches . In 
non-stres sed plants 7 0 %  of total seed yield came from 
I iii  
seedheads produced on  secondary branches and only  2 0 %  from 
primary branches . The posi tion of  s eedhead formation on 
e ach branch was also  important . The results showed that 
about 7 5-9 0 %  of  total  seed y ield  came from seedheads formed 
at  nodal  s ites. The number o f  s eedheads formed at  terminal 
s ites was low . In  later s tressed  plants and in  wel l  watered 
plants the contribution of nodal  s ites to seed yield was 
higher than in early s tressed plants . 
The results o f  the field  s tudy on Verano s tylo  and 
S iratro , and the second experiment on s tylo grown under 
controlled  environment conditions were incorporated into 
practica l  recommendations  which lead to conclusions on the 
most  economically , social ly and agriculturally acceptable  
managemen t  system for the seed production of  Verano s tyle  
and Siratro by Thai  farmers . 
iv 
ACKNOWLEDGEMENTS 
I wi sh  to express  my s i�cere appreciation to 
Dr M . J .  H i l l  and Professor B . R . Watkin , my supervisors , 
for their valuable  encouragement , patience in reading 
the manuscript and correcting my English, and their 
constructive criticisms in preparing this the s i s . 
Grateful acknowledgement i s  made to Mr I . J .  Warrington 
for his  helpful guidance , support and generosity during my 
s tay in New Zealand . 
I am also grateful for the use of  Control led Climate 
facilities  at  the P lant Phys iology Division, D . S . I . R . , 
Palmerston North , and would l ike to thank Mr L .  Ford and 
Mis s  H . L .  Turnbull  and other members of the climate room 
support group for their help and interest . 
Appreciation is  also  expressed to : 
Dr I . L .  Gordon , Mr G . C .  Arnold and Mr R . C .  Seddon 
for the ir s tatistical help . 
Staff  of  the Central Photographic Unit, Mas s ey 
Univers ity, for their  excel lent work . 
Staff  and s tudents of  Seed Technology Centre for their 
help ,  encouragement and friendship during my four years in 
New Zealand . 
Dr Sa l ly Newton for her kindnes s, encouragement , and 
companionship while  I was staying here . 
Erin Temperton for her care and patience in  typing 
this  thes i s . 
I a lso  wish to expres s  my s incere appreciation to 
Garth and Mary Anne Eyles , my New Z ealand brother and 
s ister , for their helpful encouragement and guidance 
while  I was studying here . 
V 
Finally, my grateful thanks to my mother, brothers  and 
s i sters  for their  moral  support and looking a fter  my chi ldren, 
and also  to Yongyoot, Anud and Jirud for their  valuable 
encouragement, understanding and patience . My heartfe lt  
apologies  also for neglecting them for so  long . 
The New Zealand Government for the opportunity to 
undertake this  study and Khon Kaen University for allowing 
me to carry on with this  s tudy are grateful ly acknowledged . 
vi 
TABLE OF CONTENTS 
ABSTRACT i 
ACKNOWLEDGEMENTS iv 
List  of  Tab les  vi  
List  of  Figures xvii 
List  of  Plates xvi i i  
Lis t  of  Appendices  xxi  
INTRODUCTION 1 
CHAPTER 1 
CHAPTER 2 
LITERATURE REVIEW 
1 .  Background Information 
2 .  Defoliation 
3. Water 
4. Seed Crop Development 
5 .  Crop Husbandry for Seed Production 
FIELD TRIAL 
5 
10  
1 8  
2 7  
3 2  
MATERIALS AND METHODS 3 8  
RESULTS 4 9  
PART A .  DRY SEASON PLANTING 51  
1 .  Effect of  Irrigation and Cutting 51  
on  Vegetative and Reproductive 
Development of  Sty losanthes hamata 
cv Verano 
2 .  E ffect o f  Irrigation and Cutting on  7 3  
Vegetative and Reproductive Deve lop-
ment of  Macropti liwn atropurpurewn cv 
Siratro 
DISCUSSION 9 2  
PART B .  WET SEASON PLANTING 9 4 
1 .  Effect o f  Cutting on Vegetative 9 4 
and Reproductive Development of  
Stylosanthes hamata cv Verano 
2 .  Effect of Cutting on Vegetative 1 0 3  
and Reproductive Development of  
Macroptiliwn atropurpureum cv S iratro 
PART C .  SEED QUALITY 111  
1. Sty losanthes hamata cv Verano 111  
2.  Macropti liwn atropurpurev.m cv  S iratro 1 1 5  
DISCUSSION 1 1 8  
CHAPTER 3 
CHAPTER 4 
vii  
CONTROLLED ENVIRONMENT CONDITIONS STUDY 
EFFECT OF WATER AND CUTTING ON STYLOSANTHES 
HAMATA CV VERANO UNDER CONTROLLED ENVIRON-
MENT CONDITIONS 
1 21  
INTRODUCTION 1 21  
MATERIALS AND METHODS 1 2 2  
RESULTS 1 3 0  
PART A .  The Effect of  Water and Cutting on 1 3 1  
Vegetative and Reproductive Growth 
and Yield per Plant 
PART B .  Ef fect of Water and Cutting on 1 5 7  
the Development and Seed Yield 
Contribution of Different Branch 
Orders 
PART C .  Effect of  Water and Cutting on 1 7 4  ·the Contribution to Seed Yie ld 
made by the Pos ition of  the 
Seedhead 
DISCUSSION 1 9 3  
GENERAL DISCUSS ION 1 9 7  
BIBLIOGRAPHY 
APPENDICES 
viii 
L I ST OF TABLES 
Table 
FIELD TRIAL 
A . l 
A .  2 
A .  3 
A .  4 
Dry matter yie ld per plant from non-irrigated (Wl )  
and irrigated (W2 )  plants at successive harvests  
in  Verano stylo in the dry  season planting ( g/pl )  
Total branch numbers per plant from non-irrigated 
(Wl ) and irrigated (W2 ) plants at successive 
harvests in Verano stylo in the dry season planting 
Total leaf  numbers per plant from non-irrigated 
(Wl ) and irrigated (W2 ) plants at succe s s ive 
harvests  in Verano s ty lo in  the dry season 
planting 
Total leaf area per plant from non-irrigated (Wl )  
and irrigated (W2 ) plants at  successive harvests  
in  Verano stylo in the  dry  season planting ( cm2/pl )  
5 2  
5 3  
5 3  
5 4  
A . S  Total seedhead numbers  per plant from non-irrigated 5 6  
(Wl ) and irrigated (W2 ) plants at successive 
A . 6 
A .  7 
A .  8 
A .  9 
harvests  in Verano s tylo  in  the dry season planting 
Total  seed yield per p lant from non-irrigated (Wl ) 
and irrigated (W2 ) plants at successive harvests  
in  Verano stylo in  the  dry season planting ( g/p l )  
P lant dry matter yie ld i n  cut and uncut plants at 
successive harvests  in  Verano s tylo in  the dry 
season planting ( g/pl )  
Total branch numbers per plant i n  cut and uncut 
plants at  successive harvests  in Verano s tylo  in 
the dry season planting  
Total  l eaf  numbers per plant in cut  and uncut 
plants at  succes s ive  harvests in Verano s tylo  
in  the dry season planting 
A . l O  Total leaf  area in cut and uncut plants at 
successive harvests  in  Verano s tylo  in the 
dry season planting ( cm2/pl )  
5 7  
5 9  
6 0  
6 1  
6 2  
ix 
Table Page 
A . ll Total seedhead numbe r s  per plant in cut and uncut 6 5  
p lants a t  succe s s ive harve s t s  in Verano s tylo in 
the dry season 
A.l2 Total s eed yield per plant in cut and uncut 1. 
p lants a t  succe s s ive harve s t s  in Verano s ty lo 
in the dry season ( g/pl )  
6 4  
A . l 3  Interaction between irrigation and cutting on 6 6  
dry matter yield per plant a t  success ive harve s t s  
in Verano s ty l e  in the dry s eason plant ing ( g/pl ) 
A . l4 I nteraction be tween i rrigation and cutting on 
total branch numbers  per p l ant at suc c e s s ive 
h arve s t s  in Verano s ty l e  in the dry season 
p lanting 
A . l5 
A . l6 
Interact ion between irrigation and c ut ting on 
total l eaf  number s  p e r  plant at success ive 
harves t s  in Verano s ty l e  in the dry season 
Interac tion be tween irrigation and cutting on 
total leaf area per plant at success ive harve s t s  
i n  Verano stylo  in the dry season ( cm2/pl ) . 
A . l 7  Interaction be tween irrigation and c utting on 
total  seedhead numbers per p lant at s ucces s ive 
harve sts  in Verano s tylo  in the dry season 
6 7  
6 9  
7 0  
7 1  
A . l8 Interaction be tween irrigation and cutting on 7 2  
total s eed yie l d  per pl ant a t  suc ce s s ive harve s t s  
in Verano s tylo i n  the dry season ( g/p l ) 
A . l9 Dry matter yie ld per plant at succe s s ive harve s t s  7 3  
in S iratro from non-irrigated (Wl ) and irri gated 
(W2 ) plots in the dry season planting ( g/pl ) 
A . 2 0 Total branch numbe r s  per plant a t  succe s s ive 
harve s t s  in S ir a tro from non-irr igated (Wl ) 
and irr igated ( W2 )  plots in the dry season 
plan ting 
A . 2 1  Total leaf numbe r s  per p lant at succe s s ive 
harvests  in S i ratro from non- irr igated (Wl)  
and irrigated (W2 ) plots i n  the dry season 
planting 
7 4  
7 5  
X 
Tab l e  
A . 2 2  Total leaf  area per plant a t  succe s s ive h arve s ts 7 5  
in S i ra tro from non- irr igated (Wl ) and irr igated 
(W2 )  plots in the dry season plant ing ( cm2/pl) .  
A . 2 3  Total  pod number s  per plant at suc ces s ive h arvests  7 6  
i n  S iratro from non- irr igated (Wl ) and irr igated 
(W2 ) plots in the dry s eason planting 
A . 2 4  Tota l  s eed yield per plant at succe s s ive harve s t s  7 8  
in S ira tro .from non-irr igated (Wl ) and i rr i gated 
(W2 ) pl ots in the dry season plant ing ( g/pl ) 
A . 2 5  Dry matter yield per p l ant on cut and unc ut plants 7 9  
at succe ssive harve sts in Siratro in the dry sea son 
( g/p l ) 
A . 2 6 Total branch numbe r s  per plant on cut and uncut 8 0  
plants at success ive harve s ts in S i ratro in the 
.dry season 
A . 2 7 Total  leaf numbe r s  per plant on cut and uncut 
plants at suc c e s s i ve harvests  in Siratro in 
the dry season 
8 1  
A . 2 8 Total  leaf area per plant on cut and uncut plants 8 1  
at suc cessive harve s ts in S i ratro in the dry 
season (err? /pl ) . 
A . 2 9  Total  pod numbers  per p lant on cut and uncut plants 8 2  
a t  successive harve s ts in S iratro in the dry s eason 
A . 3 0 Total seed yie ld per p lant on cut and uncut plants 8 3  
a t  succe ssive harve s ts in Siratro in the dry s eason 
(g/pl ) 
A . 3 1  Interaction be tween irriga tion and cutting on dry 8 5  
matter yield per p lant at success ive harve sts in 
S i ratro ( g/pl ) 
A . 3 2  Interaction be tween irr igation and cutting on 8 6  
total  branch numbers per p lant a t  succes s ive 
harve sts in S i ratro 
A.3 3 Interaction between irr iga tion and cutting on 
total leaf numbe r s  per plant at success ive 
harve sts  in S iratro 
8 7  
• 
xi 
T able 
A . 3 4  Interaction be tween irr i g ation and cutt ing on 
total leaf area per plant at success ive harve s t s  
i n  S iratro ( cm 2/pl ) . 
A . 3 5  Interaction be tween irrigation and cutting on 
to ta l pod numbe r s  per plant at suc ce s s ive 
harve s t s  in S i r atro 
A.3 6 Interac tion between irriga tion an d cutting on 
total seed. yie l d  per p l ant a t  succe s s ive harve sts 
in Siratro in the dry s eason planting ( g/pl ) 
B . l  
B . 2 
B . 3 
B . 4  
B . S  
Plant dry matter yield on cut and uncut plants 
of  Ver ano sty l o  in the wet season ( g/pl ) 
Tot al branch numbers  per plant on cut and uncut 
plants at success ive harve s ts of Verano s ty lo 
in the wet sea son 
Total leaf numbers per plant on cut and uncu t  
plants at succ e s s ive h arves ts o f  Ver ano stylo  
in the wet season 
Tot al leaf area per plant on cut and uncut p lants 
at successive h arvests of Verano stylo in the we t 
s e ason ( cm2 /pl ) . 
To tal seedhea d  numbers per plant on cut and uncut 
plants at success ive h arve sts o f  Verano stylo in 
the we t season 
8 8  
8 9  
9 1  
9 6  
9 7  
9 7  
9 8  
9 9  
B . 6  Tot al seed y i e l d  per p l ant on cut  and uncut plants 1 0 2  
at successive h arvests  o f  Verano s ty lo i n  the wet 
s e ason ( g/pl)  
B .  7 
B .  8 
Dry matter y i e ld per p l ant a t  success ive harves t s  
o n  .cut and uncut plants of S i r atro i n  the we t 
season ( g/p l ) 
Tot al branch numbers per plant a t  succes s ive 
h arve sts on cut and uncut plants of S i r atro in 
the wet seas on 
. .  : 
:.1. 
1 0 4  
1 0 5  
Table 
B . 9  
xii 
Total leaf numbers  per plant at s uccess ive 
harve s t s  on cut and uncut plants of  S i ra tro 
in the  wet s ea s on 
B . l O Total l eaf  area per p lants a t  succe s s ive 
harve sts on cut and uncut p lants o f  Siratro 
in the wet s eason ( cm2/pl ) 
B . l l Total pod numbers per plant on cut and uncut 
plants at succes s ive harvests  of Siratro in 
the we t sea son 
B. l 2  Tota l seed y i e l d  per p lant at s ucce s s ive 
harve s ts on cut and uncut plants of S i ra tro 
in the  wet season ( g/p l ) 
C l  
C . 2  
C . 3  
C . 4  
c.s 
C . 6  
C . 7  
Seed moisture content percentage at succe s s ive 
harvests  in dry s eason non-irrigated (Wl ) 1 
i rr igated (W2 ) and wet season ( W3 ) planting 
o f  Verano s ty l o  
S e e d  moisture content percentage a t  suc ces s ive 
h arve s ts in cut and uncut plants of Verano s tylo  
Hard seed c ontent percentage a t  success ive 
harve s ts in dry season non-irrigated (Wl ) 1 
irrigated (W2 ) and wet s eason (W3 ) plan tings 
o f  Verano s tylo  
Hard seed content percentage a t  success ive 
harve s ts in c ut and uncut plants of Verano 
s tylo  
Seed moi s ture content percentage at succes s ive 
harvests  in dry season non- irr igated (Wl ) 1 
irr igated ( W2 )  and wet season ( W3 ) plantings 
of S iratro 
' 
Seed moisture c ontent percentage at suc ce s s ive 
harve s ts on c ut and uncut plants of S i ra tro 
Germination percentage at successive harve sts 
in dry season non-irrigated (Wl ) 1 irriga ted 
(W2 ) and wet season ( W3 ) plantings of  S i ra tro 
Page 
1 0 6  
1 0 6  
1 0 7  
1 1 0  
1 1 2  
1 1 3  
1 1 4  
1 15 
1 1 6  
1 1 6  
1 1 7  
Table  
c. 8 
xiii  
Germination percentage at  succes s ive harvests  
on cut and uncut plants of  S iratro 
CONTROLLED ENVIRONMENT CONDITIONS STUDY 
A . 3 . 1  
A . 3 . 2  
A . 3 . 3  
A . 3 . 4  
A .  3 .  5 
A . 3 . 6  
A .  3 .  7 
A .  3 .  8 
A .  3 .  9 
A . 3 . 1 0 
Watering schedule  
Effect of  water  on  plant dry matter y ield 
at success ive harvests  of Verano style  
under controlled  environment conditions 
( g/p l )  
Ef fect of  water on total branch numbers per 
plant at succes sive harvests of Verano sty le 
under control led environment conditions 
Effect of  water on total leaf  numbers per plant 
at succes s ive harve sts  of Verano s ty lo under 
controlled environment conditions 
Effect of water on total leaf  area per plant 
at  succes sive harvests  of Verano s tylo  under 
controlled environment conditions ( cm2jpl ) . 
Summary o f  duration of  each s tage of  plant 
development  in  Verano stylo  from each water 
treatment under controlled environment 
conditions 
E ffect of water on total seedhead numbers per 
plant at  successive harvests  of  Verano s tylo  
under control led environment conditions 
Effect of water on total seed yield per plant 
at succes sive harves ts of Verano s tyle  under 
control led environment conditions ( g/pl ) 
P lant dry matter yield on cut and uncut plants  
at succe s sive harvests of  Verano s tyle  under 
control l ed environment conditions· ( g/pl ) . 
Total branch number per plant  on cut and uncut 
plants at  success ive harvests of  Verano sty lo 
under control led environment conditions 
Page 
1 1 8  
1 2 7  
1 3 1  
1 3 3  
1 3 4  
1 3 5  
1 3 6  
1 3 7  
1 3 8  
1 3 9  
1 4 0 
Tab l e  
A .  3 .  1 1  
A .  3 . 1 2 
A . 3 . 1 3 
A . 3 . 1 4 
A . 3 . 1 5 
A . 3 . 1 6 
A . 3 . 1 7 
A . 3 . 1 8 
A . 3 . 1 9 
A . 3 . 2 0 
xiv 
Total leaf numbers per plant on cut and uncut 
p l ants a t  success ive harvests  of Verano s tylo  
unde r  control l ed environment condi tions 
Total  l e a f  area per plant on cut and unc u t  
plants a t  success ive harvests  o f  Verano 
s tylo under control led environment conditions 
(cm2 jpl )  . 
Seedhead numbers per plant on cut and uncut 
p l ants a t  successive h arve s t s  of Verano 
s tylo under contro l led environment conditions 
Seed yield  per plant on cut and uncut p l ants 
at succ e s s ive harvests  of Verano stylo  under 
con trol led environment cond i t i ons ( g/pl ) 
Ef fect of  water and cutting on dry ma tter 
y i e ld per p l ant a t  success ive harvests  of 
Verano s tylo  under contro l l ed environment 
conditions ( g/pl )  
Ef fect o f  water and cutting on total branch 
numbers per plant at succe s s ive harve s t s  o f  
Verano s ty lo under control led environment 
conditions 
Ef fect of  water and cutting on total l e a f  
numbers p e r  plant at succes s ive harve s t s  
of  Verano s tylo under contro l l ed envi ronment 
condit ions 
Effect of water and cutting on total l e a f  area 
per plant at success ive harve s ts of  Verano 
s ty lo under contro l l ed environment cond i tions 
(cm2/pl ) . 
Ef fect o f  water and cutting on seedhead numb e r s  
p e r  plant a t  succe s s ive harve s ts of  Verano 
s ty lo under control led environment cond i tions 
Ef fect o f  water and cutting on seed yield  per 
plant a t  s ucces s ive harve s ts of Verano s tylo 
under control led environment conditions ( g/p l ) 
1 4 1  
1 4 2 
1 4 3 
1 4 4 
1 4 6  
1 4 8 
1 5 3  
1 5 4  
1 5 5  
1 5 6  
Table 
B . 3 . 1  
B . 3 . 2  
B . 3 . 3  
B . 3 . 4 
B . 3 . 5  
B . 3 . 6  
B . 3 . 7  
XV 
Ef fect of  water on the numbe r  o f  primary , 
s econdary , ter tiary and quaternary branche s 
per plant a t  s ucces s ive harve s ts of Verano 
s tylo under contro l led environment condi tions 
Ef fect of  water on the seedhead numbers formed 
on primary , secondary and tertiary branches 
at succ e s s ive harve sts of Verano stylo under 
control led envi ronmen t  cond i t i on s  
Ef fect o f  water on the numbe r  of  seeds per 
s eedhead formed on primary , secondary and 
tertiary branches at succe s s ive harve sts  
of  Verano s ty lo under contro l l ed environmen t  
conditions 
Ef fect of  water on seed yield  per p l an t  formed 
on pr imary , s econdary and ter ti ary branches a t  
success ive harvests  of Verano s tylo unde r  
control l ed environment cond i tions ( g/p l )  
Ef fect o f  cutting on the numbe r  of pr imary , 
secondary , tertiary and quaternary branches 
per plant a t  success ive harve s t s  of Verano 
s tylo under control l ed environment cond i tions 
Ef fect of cutting on the s eedhead numbers 
formed on  pr imary , secondary and tertiary 
branches a t  suc c e s s ive harve s t s  of Verano 
s tylo under control l ed environment conditions 
Ef fect of cutting on s eed y i e ld per plant 
formed on pr imary , s econdary and tertiary 
branches at succe s s ive harves t s  of  Verano 
s tylo under contro l led environment condi tions 
(g/pl ) 
Page 
1 5 8  
1 6 0  
1 6 2  
1 6 3  
1 6 5  
1 6 7  
1 6 8  
Tabl e  
C.3 . 1  
C . 3 . 2  
C . 3 . 3  
C . 3 . 4  
C . 3 . 5  
C . 3 . 6  
C . 3 . 7  
xvi 
Number of seeds per s eedhead at nodal and 
termina l pos i tions formed on primary , 
secondary and ter tiary branches at 
success ive harve s ts in Verano s ty le under 
contro l l ed envi ronment condi t ions 
Ef fect o f  water on s eedhead numbers a t  nodal 
and terminal pos i tions formed on pr imary , 
s econdary and terti ary branches at succe s s ive 
harvests in Verano s ty l e  under c ontrolled 
environment conditions 
·Ef fect of water on s eed yie ld at  nodal  and 
termina l pos i tions on pr imary , s econdary 
and tert iary branches at  succes s i ve harve s ts 
in Verano s ty l e  under contro lled environment 
condi tions ( g/pl )  
Ef fect o f  water on s eed yie ld  formed at nodal 
and terminal pos i tions at s uccessive harvests 
in Verano s ty l e  unde r  c ontro l led environment 
condit ions ( g/pl )  
Ef fect of  cutting on seedhead numbers  a t  nodal 
and termina l pos i tions on pr imary, secondary 
and tertiary branches at  succe s s ive harves ts 
in Verano s ty l e  under contro l led environment 
condi tions 
Ef fect of  cutting on seed yie ld at nod a l  
and terminal pos i t ions on pr imary , secondary 
and tertiary branches at succe s s ive h arve s ts 
in Verano s ty l e  under control led  environment 
conditions ( g/pl )  
Summary o f  the percentage o f  the contribution 
of the seed yield formed on e ac h  branch order 
and pos i t ion at 25 days a fter peak f lowe ring 
in Verano style under contro l led environment 
conditions 
Page 
1 7 5  
1 7 3  
1 7 9 
1 8 1  
1 8 3  
1 8 5  
1 9 1  
xvi i  
LIST OF F IGURES 
Fi gure 
F I ELD TRIAL 
1 
2 
3 
4 . 
5 
6 
Experimental layout for cutting and irrigation 
of  the fie ld trial in the d ry se ason 
Time o f  sowing , cutting treatments , irrigation 
period ,  f loral initia tion , peak flowering 
schedu le and rain fa l l  of the f i e ld tria l s  
F lowering curves of  Verano s ty l o  from non­
irr igated (Wl ) and irr igated (W2 ) plants in 
the dry season planting 
Flowering curve s of Siratro from non-irr igated 
(Wl ) , irrigated (W2 ) plants in the dry se ason 
planting 
Flower ing c urve of Verano s ty l o  plants in the 
wet season 
Flowering curve of  Siratro p l ants in the 
we t season planting 
CONTROLLED ENV I RONMENT CONDITIONS STUDY 
3 . 1  
3 . 2  
3 . 3  
3 . 4  
Ef fect of  water and cutting on the numbers 
of  branch order at succ e s s ive harvests of  
Verano s ty l o  und er contro l l ed envi ronment 
conditions 
Ef fect of water and cutting on the numbers o f  
seedhead formed o n  each branch order a t  
succe s s ive harve s ts of  Verano stylo under 
contro l l ed environment cond i t ions 
Ef fec t  o f  water and cutting on the seed yield  
formed on  each branch order a t  success ive 
harve s t s  o f  Verano s tylo  under control led 
environment cond i t ions ( g/pl ) 
Ef fec t o f  water and cutting on  seed yield 
formed on each branch order and pos i t ions 
at  succ e s s ive harve s ts of Verano s ty lo 
under controlled environmen t  conditions 
(g/pl ) 
4 0  
5 0  
5 5  
7 7  
1 0 1  
1 0 8  
1 7 0  
1 7 2  
1 7 3  
1 8 9 
xviii 
LIST OF PLATES 
Plate 
F IELD TRIAL 
1 
2 
3 a  
3 b  
4 a  
4b 
5 
6 
7 
8 
Wel l  prepared seedb ed 
Sowing the seeds 
Cutting treatments at vege ta tive growth 
stage o f  Verano S ty lo 
Cutting treatment at floral initiation 
growth s tage of Verano s ty lo 
Cutting treatment at veg e ta tive growth 
s tage o f  S iratro 
Cutting treatment at floral initiation 
growth s tage of Siratro 
Wel l  grown Verano stylo p lants in 
the we t s eason 
We l l  grown Siratro plants in the we t season 
C l ose up view of  Verano s ty l o  plants 
at peak f lower ing s tage 
Close up view o f  S iratro p l ants a t  
peak f lowering s tage 
CONTROLLED ENVI RONMENT C ON DITIONS STUDY 
3 . 1  
3 . 2 a 
3 . 2b 
3 . 2 c 
3 . 2 d 
Stylosanthes hamata cv Verano s eedlings 
10 days a f ter sowing 
Uncu t  ( Co)  and cut plants at vege ta tive growth 
s tage ( �VG and �VG )  3 0  days after sowing 
Uncut ( C o )  and cut plants at floral initi a tion 
growth s tage ( �F I  and �F I )  o f  W2 and W3 
tre a tments 4 0  days after sowing 
Unc ut ( Co )  and � of plan t  c anopy removed a t  
floral initiation growth s tage ( �F I ) o f  Wl 
trea tment 
Uncut ( Co )  and � of  plant c anopy removed at 
floral ini tiati on growth s tage ( �F I )  of 
Wl treatment 
3 9  
4 2  
4 5  
4 5  
4 6  
4 6  
9 5  
9 5  
l OO 
1 0 9  
1 2 3  
1 2 5  
1 2 5  
1 2 6  
1 2 6  
P l ate 
3. 3 a  
3 . 3b 
3 . 3c 
3 . 4  
3 . 5  
3 . 6  
3 . 7  
3 . 8  
xix  
Plants rece iving 'Low ' watering at vegetat ive 
growth s tage (Wl ) 
P lants receiving 'Low' watering at peak 
f lower ing s tage (W2 ) 
Plants rece iving 'High' watering throughout 
the g rowing period (W3 ) 
Uncut and e arly l ight cut plants of Verano 
s tylo which had been stre s s ed early in the i r  
vegetative growth ( Wl ) . Photo taken a t  
f inal harve s t  3 0  days a f te r  peak flowering 
Uncut and e arly li gh t cut p l ants of  Verano 
s tylo wh ich had been stre s sed from peak 
f lowe r ing (W2 ) . Photo taken a t  final 
harve s t  30 days a fter peak f l owering 
Uncut and e ar ly light cut p l ants of Verano 
s tylo  which had rece ived adequate wa ter 
throughout the e xper iment ( W3 ) . Photo t aken 
at final  harve s t  30 days a f te r  peak f lower ing 
Showing the relative s i ze of inflores cenc es 
a t  nodal and termina l  pos i t ions in Verano stylo 
Diagrams s howing nodal and termina l pos ition 
seedheads on each branch order of Verano 
s tylo p l ants from al l water and cutting 
treatments 2 5  days after peak f lowering 
GENERAL D I SCUS S I ON 
4 . 1  
4 . 2  
4 . 3 
Siratro plant showing extreme primary branch 
length but comparatively few highe r  order 
branches 
Verano s tylo p lant showing the capacity to 
increase the number of  h igher order branches 
Siratro sward showing profuse  pods product ion 
fol lowing alte rna ting wet and dry conditions 
1 3 2  
1 3 2  
1 3 2  
1 4 9  
1 5 0  
1 5 1  
1 7 6  
1 8 6  
2 0 0  
2 0 0  
2 0 1  
P late 
4 . 4  
4 . 5  
4 . 6 a 
4 . 6b 
4 . 6 c  
4 . 7 
4 . 8  
4 . 9  
4 . 1 0 
APPEND I X  
3.9 a 
3. 9b 
3. 9 c  
XX 
S i ra tro swar d  in the wet season showing 
.profuse vegetati ve growth and re lati ve ly 
f ew seedpods 
General vi ew of  Verano s tylo  in the we t 
season at peak f lower ing s tage 
F i e l d  grown uncut p lant with no irri ga tion 
in the dry s eason at 15 day s  a f ter peak 
f l owering 
F i e l d  grown cut plant ( �F I )  wi th no irriga tion 
in the dry s eason at 15 days a f ter peak 
f l ower ing 
P l ants grown in the control led environment 
c ondit ions at 15 days after peak f l owering 
Verano s ty l o  p l ants .in the f i e l d  in the dry 
season showing s evere leaf she dding 
Verano sty lo plants under severe water 
stress  showing more vertical  or ientation 
of leaves ( lea f-clos ing ) 
General view o f  dry season p lanting of  
Verano s ty lo ,  showing the effect  o f  90  day s  
wi thout rain fal l or irrigation 
General vi ew o f  the dry season planting o f  
S i ratro , s howi ng th e abi l ity o f  Siratro in 
tol erating the dryne s s  of  9 0  days without 
rain fal l or irrigation 
Ear ly an d heavy cut at vegetative growth s tage 
of Verano s tylo  from a l l  water treatments a t  
f inal harve s t  3 0  days after peak flowering 
Late and l ight cut a t  f loral initiation growth 
s tage of Vera no s ty lo from a l l  water treatments 
a t  fina l harve s t  30  days a f te r  peak f lowering 
Late and h e�vy cut a t  f loral initiation s tage 
of  Verano s ty l o  from a l l  water treatments a t  
f inal harve s t  3 0  days a fter peak flowering 
Page 
2 0 1  
2 0 2  
2 0 4  
2 0 4  
2 0 4  
2 0 7  
2 0 7  
2 0 9  
2 0 9  
xxi 
LIST  OF APPENDICES  
APPENDIX 
l . a Number o f  seeds per s eed head of  cut and uncut 
plants  from non-irrigated (Wl) , irrigated (W2 ) 
in the dry season and wet s eason (W3 ) p lanting 
at succes sive harves ts  o f  Verano s tylo . 
l . b  One hundred s eed  weight o f  cut and uncut p lants  
from non-irrigated (Wl ) ,  irrigated (W2 ) in the 
dry seas on and wet seas on (W3 ) p lants  at 
succes sive harvests  o f  Verano s tylo . 
2 . a  Number o f  seeds per pod  of  cut and uncut p lants  
from non-irrigated (Wl)  , irrigated (W2)  in the 
dry s eas on and wet s eason (W3 ) p lanting at  
successive harves ts of  Siratro . 
2 . b  One hundred seed weight of cut and uncut p lants  
from non-irrigated (Wl) , irrigated (W2) in the 
dry s eas on and we t seas on (W3) p lanting at  
succes sive harvests  o f  Siratro . 
3 . 1 Treatment conditions  in each CE room . 
3 . 2  Climate Lab - N . C . S . U .  Phytotron Nutrient 
3 . 3  E ffec t  of  water and cutting on the numbers  of  
branch ord e r  per p lant at  successive harves ts  
of  Verano s tylo under controlled  conditions . 
3 . 4  Effect  of  water and cutting on leaf number per  
plant  on  each branch order at  successive harve s ts 
o f  Verano s tylo under control led  conditions . 
3 . 5 Effect  o f  water and cutting on leaf area on each 
branch order at succe s sive harvests  o f  Verano 
s tylo under controlled  conditions ( cm2/ p l ) . 
3 . 6 E ffect  of  water and cut ting on seed head numbers 
formed on each branch order at  succes sive 
harves ts  o f  Verano s tylo under contro lled 
environment conditions . 
xxii 
APPENDIX 
3 . 7  Effect  of  water and cutting on seed yield  formed 
on each branch order at succes sive harves ts of  
Verano s tylo under controlled  environment 
conditions (g/p l ) . 
3 . 8  Effect  of  water and cutting on seed head numbers  
on each branch order and positions at succes sive 
harves ts  of  Verano s tylo under the controlled  
environment conditions . 
3 . 9 E ffe ct  of  water and cutting on seed yield  formed 
on each branch order and positions a t  succes sive 
harve s ts o f  Verano s tylo under the con trolled 
conditions ( g/pl ) . 
3 . 10 a  Early and heavy cut at vegetative growth s tage 
o f  Verano s tylo from all  water treatment s  at 
final harves t 3 0  days after peak flowering . 
3 . 10b Late and light cut at  floral  initiation growth 
s tage of  Verano s tylo from all  water treatments  
at  final  harves t 30  days after peak f lowering . 
3 . 10 c  Late and heavy cut at floral initiation s t age 
3.11 
3 . 12 
3:i3 
of Verano s tylo  from all  water treatments at 
final  harves t 30 days after peak flowering . 
Effect of water and cutting on seed mois ture 
content  percentage at suc ces sive harves ts of  
Verano s tylo under the controlled environment 
conditions . 
Effe ct  of water and cutting on 100  s eed weight 
at successive harves t of  Verano s tylo  under the 
controlled environment conditions . 
Effect  of  water and cutting on seed mois ture 
content  percentage at succes sive harve s ts of  
Verano s tylo under the controlled environment 
conditions.