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A STUDY OF THE VEGETATIVE AND REPRODUCTIVE MORPHOLOGY OF 
GRASSLANDS HUlA WHITE CLOVER (7�itofium �epen� L.) WITH 
EMPHASIS ON THE EFFECTS OF DEFOLIATION AND PARAQUAT 
ON SEED YIELD AND QUALITY 
CARLOS EDUARDO ROMERO MALDONADO 
1985 
Depicting vegetative and floral parts of white 
clover plant. 
Inflorescence 
Seed Pod Single Seed 
ABSTRACT  
The pre sent s tudy examined the  effect of management syst ems , par t icularly  
closing date and paraquat app lication, on the  vegetative and reproducti ve 
morphology of'Grasslands Hui a' whi te  clover (Tri folium repens L. ) over  
two succes s i ve years  i n  a fi eld mi xed  (grass  and clover ) sward s i tuation. 
More detai l e d  s tudi es  involving two di fferent genotypes  of 'Grasslands 
Hui a' whi t e  clover grown in  monoculture were al so carri ed out to examine 
the effect s of cut t ing and paraquat app l icati on. 
The mi xed  sward studi es  cl early  showed  that November closing dat e s  
resul ted  i n  highest  seed  yi elds. In  grass/clover swards the closing 
of crQps in  November accompani ed by paraquat spraying to remove grass  
compe t i tion ei ther  i n  mi d October or at closing ,  enhanced seed yi e ld. 
Later  grazi ng and spraying was deleterious to  seed  yield  unles s  climatic  
condi t ions al lowed continued vegetat i ve growth  into December. I n  thi s 
lat ter  case  spraying in  November and closi ng in  December gave high seed  
yi elds.  Treatment s i nvolving closing in  Sept ember and October and 
spraying 30 day s  before , at closing or 30 day s  after closing ,  always 
gave l e s s  seed  y ield  than November treatment s sprayed  30 days before or 
at closing time. 
Closing time  and spraying time had a marked  e ffect on seed y i e ld  component s. 
The mos t consi s t ent and major effect of closing and spraying treatment s 
in  the  two mixed  sward experiment s was on inflorescence numbers. Other  
component s such as  seed  set,  seed weight,  and floret  numbers were not 
consistent ly  i nfluenced by management but di d vary according to envi ron­
mental condi tions. 
Studi e s  on the e ffect s of cut tings and paraquat applicat ion on p lant 
s tructure and on seeding potential and yi e ld  of 'Grasslands Hui a' whi t e  
clover  cl early  showed that there i s  a parti t ioning between vege tative  
growth  and reproducti ve development. The vegetative  process  was  charac­
teri sed  by a h igh percentage of the  nodes  on main  s tolons forming l at eral 
s tolons in  the  winter  and early  spring. Reproducti ve development i n  late  
spring and summer showed that  approximately  80% of  inflorescences were 
formed  on main stolons . Highest  inflorescence numbers  were produced 
from nodes formed  in  October and November , a l though floral ini ti at i on 
s tarted  during late  winter  (August ) .  The two genotypes  used i n  thi s 
study showed  consi derable variation i n  relat ion to  reproducti ve develop­
ment . Di f ferences of 47% in  inflorescence numbers , 25% in seeds  per 
floret  and 13% in  seed  weight  were observed between genotype s. 
The effect s of defoli ation by cut t ing involved a reducti on in  stolon 
elongati on and a general  increase  i n  l ateral s tolon production ,  
particularly  when t ermi nal buds were also removed. Both l ight  and 
heavy cut t ing treatment s result e d  i n  seed  yi e l d s  which were 70 to 90 
kg/ha l e s s  t han the 657 kg/ha produced by uncut p lant s. The effect of 
paraquat app l ication was al so detrimental to seed  yi e l d , mainly through 
a di rect e ffect on whi t e  clover morphology. A lthough paraquat reduced  
the  amount of  l at eral branching on the  main s tolon the  de struction of 
s tolon t i s sue by the  herbicide reduced plant recovery and resulted  i n  
a seed  yi e l d  of  only  392 kg/ha compared  wi th  657 kg/ha from unsprayed  
plant s. Thi s  effect was most  pronounced in pure swards  of whi te  clover 
and was l e s s  obvious when the grass  component of a mi xed  sward provi ded  
some prot ection for the  whi te  clover by reducing the  extent of  di rect 
contact wi th  the  herbici de. 
Some pot ent i al areas for future r e search and the  potenti al for whi t e  
clover s e ed  producti on in  Colombi a are also di scussed. 
ii 
ACKNOWLEDGEMENTS 
There are many people I wish to thank for their  understanding and 
support during my studies in New Zealand. 
but I thank them al l .  
I can mention only a few 
Those principally  involved were : 
Dr Murray H i l l ,  Director 
beginning of my research 
read and corrected the 
constructive criticism .  
of  the Seed Technology Centre who since the 
has been a source of he lp and support .  He 
manuscript improving my english and making 
Professor B . R .  Watkin ,  Head of the Department of Agronomy who guided 
and instructed me during the first part of the research work .  
Dr M . P .  Rolston , of the Grasslands Division , DSIR ,  who provided guidance 
and help during the programme . 
Professor R . G .  Thomas for hi s invaluable and constant help during the 
preparation of this thesis . His  support is very much appreciated . 
I a l so thank Mrs D .  Meech , Mrs K .  Johnstone , Mrs R .  Ca lton, 
Johnstone and Mr G .  Walter for their technical a ssistance 
laboratory work and in the scanning electron micrographs . 
Mr R . C .  Seddon for his  help in computing the data . 
Mr C . R .  
in  the 
Sta f f  and students of Seed Technology Centre and the technicians of 
the Agronomy Department , especially  Mr T . J .  Lynch,  Mr M. C .  Thomson 
and Mr R . F .  Battersby for their  support and the use of their technical 
faci lities . 
Mrs Anne Davies for her patience and care in typing the draft of 
the manuscript . 
Mrs Veronica Fi.eldsend for her care in the f inal typing of the manuscript . 
i i i  
My gratitude is  a lso expressed to the New Zealand and Colombian  
Governments who al lowed me to  complete my  study programme . 
Final ly ,  my warmest  thanks to Maria Isabel , Carlos and Cami lo for their  
patience , support and understanding . 
iv 
CONTENTS 
PAGE 
Abstract 
Acknowledgements i i  
List of Tables vi i i  
List of Figures xii 
List of Plates xiv 
List of Appendices XV 
INTRODUCTION �· 
CHAPTER I - REVIEW OF LITERATURE 4 
A - General Description of White Clover 4 
B - Vegetative Morphology and Growth · 6 
1 - Stolen Structure and Growth 6 
2 - Branching 9 
3 - Leaf and Petiole Growth 10 
4 - Root Growth 11 
C - Reproductive Morphology and Growth 12 
1 - Inflorescence Structure and Growth 12 
2 - Fac� which af fect Inf lorescence Development 13 
D - Ef fect of Flowering on Vegetative Growth 16 
E - Seed Structure and Development 16 
F - Seed Yield Components and Seed Quality 20 
G - Seed Crop Management 23 
1 - Seed Product ion 23 
2 - Effect of De fol iation on Vegetative Growth , 
Reproductive Growth and Seed Production 28 
H - Paraguat Properties 32 
CHAPTER II - EFFECTS OF CLOSING DATE AND TIMING OF PARAQUAT 
APPLICATION ON VEGETATIVE AND REPRODUCTIVE GROWTH 
OF HUIA IN MIXED SWARDS 33 
A - Field Experiment 1982 - 1983 33 
1 - Introduction 33 
2 - Materials  and Methods 
a - Experimental Site and Field Procedures 
b - Plant Measurements and Stati stical Analysis 
3 - Results 
a - Ef fect of Treatments on Dry Weight of grass and 
Dead Matter 
b - Ef fect of Treatments on White Clover Dry Weight 
c - Ef fect of Treatments on Clover Leaf Area Index 
d - Ef fect of Treatments on Number of Nodes and 
Terminal Buds 
e - Effect of Treatments on the Date of Peak 
Flowering 
f - Effect of Treatments on Seed Yield and Yield 
Components 
g - Effect of Treatments on Seed Quality 
h - Relationship Between Seed Yield and Yield 
Components 
B - Field Experiment 1983 - 1984 
1 - Introduction 
2 - Materials  and Methods 
a - Experimental Site and Field Procedure 
b - Plant Measurements and Statistical Analysis 
3 - Results 
a - Ef fect of  Treatments on Grass  and Dead Matter 
Dry Weight 
b - Effect of Treatments on White Clover Dry Weight 
c - Ef fect of Treatments on White Clover Leaf Area 
Index and Leaf let Area 
d - Ef fect of Treatments on Number of Nodes , 
Terminal buds and Stolon Length 
e - Ef fect of Treatments on Branch Production 
per Stolon 
f - Relationship between Vegetative Characters 
g - Ef fect of Treatment on the Number of 
Inflorescences 
h - Relationship between Inf lorescences/m
2 
a:nd 
Vegetative Characters 
i - Effect of Treatments on the Date of Peak 
Flowering 
V 
PAGE 
33 
3 3  
37 
3 9  
3 9  
42 
45 
47 
50 
50  
61 
65 
67 
6 7  
6 7  
6 7  
70 
·10 
70 
n 
75 
77 
82 
92 
85 
B:Z 
90 
j - Ef fect of Treatments on the Seed Yield and 
Yield Components 
k - Ef fect of Treatment on Seed Quality 
l - Relationship between Seed Yield and Yield 
Components 
C - Di scussion 
CHAPTER Ill - STUDY OF THE GROWTH PATTERN OF HUlA AND 
THE EFFECT OF CUTTING AND PARAQUAT ON ITS 
REPRODUCTIVE DEVELOPMENT AND SEED YIELD 
A - The Importance of Plant Structure on Seeding Potential  
and Yield 
1 - Introduction 
2 - Materials  and Methods 
a - Experimenta l Site and Field Procedures 
b - Plant Measurements 
3 - Results 
a - Vegetative Growth and Development 
b - The Morphology of Inflorescence Initiation 
and Development 
c - Seed Yield and Seed Yield Components 
4 - Discussion 
B - Effect of Paraquat Application and Cutting Intensity on 
Reproductive Growth and Seed Yield 
1 - Materials and Methods 
a - Experimenta l Site and Field Procedures 
b - Plant Measurements and Statistical  Analysis  
2 - Results 
a - Ef fect of  Defol iation Treatments on White 
Clover Vegetative Growth and Development 
b - Ef fect of Defol iation Treatments on White 
Clover Reproductive Growth and Development 
c - Effect of  Defoliation Treatments on \'lhite 
Clover Yield Components and Seed Yield 
d - Effect of Defol iation Treatments on White 
Clover Seed Qual ity 
3 - Discussion 
vi 
PAGE 
91 
97 
101 
102 
109 
10':1 
109 
110 
110 
112 
115 
115 
124 
141 
144 
146 
147 
147 
148 
149 
149 
158 
162 
167 
167 
,• 
- .  
CHAPTER IV - GENERAL DISCUSSION 
- CONCLUSIONS 
APPENDICES 
BIBLIOGRAPHY 
vii 
PAGE 
171  
179  
183  
208 
TABLE 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
1 6  
LIST OF TABLES 
Treatments used and their identification 1982/83 
Effect of closing time a�d paraquat treatments 
on grass dry weight (g/m ) 
Effect of closing time and par�quat treatments 
on dead matter dry weight (g/m ) 
Effect of closing time and para�uat treatments 
on white clover dry weight (g/m ) 
Effect of closing time and paraquat treatments 
on white clover leaf area index 
Effect on closing time an� paraquat treatments 
on the number of nodes/dm 
Effect of closing time and paraqu�t treatments 
on the number of terminal buds/dm 
Effect of closing time and paraquat treatments 
on the date of peak flowering 
Effect of closing date and time of paraquat 
application on seed yield per unit area (kg/ha) 
Effect of closing date and time of paraquat 
a�plication on the total number of inflorescences/ 
m present at each harvest 
Effect of closing date and time of paraquat 
application on the number of florets per 
inflorescence at peak flowering 
Effect of closing date and time of paraquat 
application on the seed number per floret 
present at each harvest 
Effect of closing date and time of paraquat 
application on 1000 seed weight (g) at each 
harvest 
Correlation coefficients between seed yield 
(kg/ha) and yield components 
Treatments used and their identification 
Effect of closing date and time of p�raquat 
application on grass dry weight (g/m ) 
viii 
PAGE 
37 
40 
41 
4J 
46 
48 
49 
52 
55 
57 
58 ' 
60 
66 
68 
71 
TABLE 
17 
18 
19 
20 
21 
22 
23 
24 
Effect of closing date and time of paraqua� 
application on dead matter dry weight (g/m ) 
Effect of closing date and time of paraquat
2 
application on white clover dry weight (g/m ) 
Effect of closing date and time o� p�raquat 
application on leaf area index (m /m ) 
Effect of closing date and time2of paraquat 
application on leaflet area (mm ) 
Effect of closing date and time of pa2aquat 
application on the number of nodes/dm 
Effect of closing date and time of paraquat 
applica1ion on the number of terminal 
buds/dm 
Effect of closing date and time of paraquat 
application on the length (mm) of main stolon 
Effect of closing date and time of paraquat 
application on the number of branches per 
stolon 
25 Effect of closing date and time of paraquat 
application on the strength of2
association 
between clover dry weight (g/m ) and some 
vegetative characters measured every 15 days 
after the completion of each treatment until 
harvest 
26 
27 
28 
29 
30  
Effect of  closing date and time of  paraquat 
application on t�e total number of 
inflorescences/m 
Correlation coefficient for eac� treatment 
between inflorescence numbers/m emerged at 
different time of the year and several 
vegetative characters of white clover plants 
Effect of closing date and time of paraquat 
application on the date of peak flowering 
Effect of closing date and time of paraquat 
application on seed yield (kg/ha) 
Effect of closing date and time of paraquat 
2 
application on the number of inflorescences/m 
at harvest 
ix 
PAGE 
73 
74 
76 
78 
79 
80 
81 
83 
84 
85 
87 
90 
91 
-93 
TABLE 
31 
32 
33 
34 
35 
36 
37 
38 
Effect of closing date and time of paraquat 
application on the number of florets per 
inflorescence at harvest 
·� 
Effect of closing date and time of paraquat 
application on the number of seeds per 
floret at harvest 
Effect of closing date and time of paraquat 
application on 1000 seed weight (g) 
Effect of closing date and time of paraquat 
application on normal seedling percentage 
Effect of closing date and time of paraquat 
application on abnormal seedling percentage 
Effect of closing date and time of paraquat 
application on hard seed percentage 
Effect of closing date and time of paraquat 
application on dead seed percentage 
Correlation coefficients between seed yield 
and yield components from plots closed at 
different dates and sprayed with paraquat 
39 Total number of nodes, lateral stolons, 
lateral branches, axillary buds, and 
inflorescences present in February at the 
nodes, which emerged from terminal buds 
of main stolons from July to January 
40 
41 
42 
Changes in petiole and peduncle length, 
inflorescence size, and number of ovules 
per floret with the time of the year 
Variation in yield components and seed yield 
between two 'Grasslands Huia' genotypes 
Treatments used and their identification 
43 Effect of defoliation treatments on the 
number of nodes emerging from the 
terminal bud per month on a main stolon 
from November to January 
44 Effect of defoliation treatments on the 
increment in length (mm) of a main stolon 
during each month from November to 
January 
X 
PAGE 
94 
95 
96 
97 
98 
99 
100 
101 
119 
139 
141 
148 
150 
151 
xi 
TABLE PAGE 
45 Effect of defoliation treatments on the 
number of leaf primordia per terminal 
bud 
46 Effect of defoliation treatments on the 
number of lateral stolons present in 
February at nodes which emerged from 
teriminal buds of main stolons during each 
month from November to January 
47 Effect of defoliation treatments on the 
number of lateral branches present in 
February at nodes which emerged from 
terminal buds of main stolons during 
each month from November to January 
48 Effect of defoliation treatments on the 
number of rooted notes present in 
February at nodes which emerged from 
terminal buds of main stolons during 
each month from November to January 
49 Effect of defoliation treatments on the 
number of inflorescences present in ten 
terminal buds of main stolons every 15 
days from November to January 
50 Effect of defoliation treatments on the 
time of inflorescence initiation in ten 
terminal buds of main stolons every 15 
days from November to January. 
51 Effect of defoliation treatments on the 
total number of inflorescences emerged 
52 
53 
on main stolons plus lateral stolons, present 
in February at nodes which emerged from 
terminal buds during each month from November 
to January 
Effect of defoliation treatments on white 
clover yield components 
Effect of defoliation treatments on white 
clover seed yield (kg/ha) 
54 Effect of defoliation treatments on white 
clover seed quality 
154 
156 
157 
158 
159 
160 
161 
164 
166 
168 
FIGURE 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
LIST OF FIGURES 
Vegetative and floral parts of a white clover 
plant 
a) External and internal morphology of a legume 
seed and 
b) Anatomical features of a legume seed coat 
Trial layout. Field experiment 82/83 
Effect of closing time on the percentage of 
normal seedlings, abnormal seedlings, hard seed, 
dead seed and viable seed at each harvest 
Effect of paraquat spraying time on the percentage 
of normal seedlings, abnormal seedlings, hard seed, 
dead seed and viable seed at each harvest 
Trial layout. Field experiments 83/84 
Effect of closing t�me and paraquat treatments 
on seed yield .!g/m ) Two year experiments 
Vegetative and floral organs of a white clover 
plant 
Number of nodes emerging from the terminal bud 
on main stolons per month 
Monthly incremental length increase in main 
stolons (July to January) 
Total number of lateral stolons present in 
February at nodes which emerged from terminal 
buds on main stolons from July to January 
12 Number of lateral stolons of different lengths 
present in February at nodes which emerged 
from terminal bud of twenty main stolons from 
July to January 
13 Number of lateral branches and axillary buds 
present in February at nodes which emerged 
from terminal buds of main stolons from 
14 
July to January 
Percentage of rooted nodes present in February 
at nodes which emerged from terminal buds of 
main stolons from July to January 
xii 
PAGE 
17 
35 
62 
63 
69 
106 
111 
116 
117 
118 
121 
122 
123 
FIGURE 
1 5  
1 6  
17  
18  
1 9  
20  
Diagramatic representation of stages of 
inflorescence and node development in white 
clover relative to distance from stolon apex 
under natural spring conditions. Thomas ( 1981 ) 
Estimated time of inflorescence initiation in 
10  terminal buds on main stolon from July 
to February 
Number of inflorescences present in ten 
terminal buds on main stolons from July to 
February 
Number of inflorescences emerged on main 
stolons and lateral stolons from September 
to January 
Number of white inflorescences present per 
unit area 
Number of white inflorescences produced in 
paraquat and cutting treatments 
xiii 
PAGE 
125 
132 
133 
1 35 
1 37  
163  
LIST OF PLATES 
PLATE 
1 Knapsack sprayer used for paraquat application 
2 Portable shearing machine used in cutting 
treatments 
3 
4 
5 
6 
7 
8 
9 
10 
11 
Damage caused by paraquat in white clover 
leaves one week after spraying 
Damage caused by paraquat application to 
white clover inflorescence one week after spraying 
Scanning electronmicrograph showing the 
morphological appearance of a leaf 
primordium (x 550) 
Scanning electron micrograph showing flower 
initiation (x 430) 
Scanning electron micrograph showing floret 
initiation (x 300) 
Stage of growth of an inflorescence at 
early emergence (x 60) 
Stages of development of inflorescences 
after emergence 
Differences in flowering density between 
the two genotypes in December 1984 
Ovules present in an unfertilised floret (x 60) 
12 X-ray photograph showing changes in the 
number of ovules forming seeds in individual 
florets 
13 
14 
Effect of heavy cut and paraquat treatments 
on main stolons of white clover 7 days 
after treatment application 
Recovery growth of white clover stolon 
after paraquat application 
xiv 
PAGE 
34 
36 
89 
89 
126 
127 
128 
130 
130 
136 
140 
142 
152 
155 
LIST OF APPENDICES 
APPENDICES 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11  
12 
13 
Soil analysis of the experimental field 
Basic weather data for Palmerston North; 
mean values for each month over the 
experimental period 1982 - 1983 
Effect of closing time and paraquat 
treatment on soil moisture content 1982-1983 
Effect of closing time and paraquat treatment 
on normal seedling percentage 1982-1983 
Effect of closing time and paraquat treatments 
on abnormal seedling percentage 1982-1983 
Effect of closing time and paraquat treatments 
on hard seed percentage 1982-1983 
Effect of closing time and paraquat treatments 
on dead seed percentage 1982-1983 
Effect of closing time and paraquat treatments 
on viable seed percentage 1982-1983 
Basic weather data for Palmerston North: 
mean values for each month over the 
experimental period 1983-1984 
Effect of closing time and paraquat treatments 
on soil moisture content 1983 - 1984 
Variation in number of florets in ten 
inflorescences at harvest 1983-1984 
Basic weather data for Palmerston North: 
mean values for each month over the 
experimental period 1984 - 1985 
Increase in length of main stolons from 
July to January 1984-1985 
14 Number of lateral stolons of different 
sizes present in February on main stolons 
from July to January 1984-1985 
15  Percentage of rooted nodes present in 
February at nodes which emerged 
from terminal buds of main stolons from 
July to January 1984-1985 
XV 
PAGE 
183 
184 
185 
186 
187 
188 
189 
190 
191 
192 
193 
194 
195 
196 
197 
APPENDICES 
16 
17 
18  
19 
20 
21 
22 
23 
24 
25 
Estimated time of initiation of inflorescences 
in 10 terminal buds of main stolons from 
July to January 1984-1985 
Number of inflorescences present in ten 
terminal buds on main stolons from July 
to January 1984-1985 
Number of inflorescences on main and 
lateral stolons, present in February, on 
nodes which emerged from terminal buds 
on main stolons from September to January 1984-1985 
Number of white inflorescences per unit 1984-1985 
area 
Changes in petiole and peduncle length, 
inflorescence size, number of ovules per 
ovary, and seed numbers per pod in 
Genotype I and Genotype II 1984-1985 
Effect of defoliation on the number of 
inflorescences per main stolon present in 
February at nodes which emerged from 
terminal buds of main stolons from 
November to January 1984-1985 
Effect of defoliation on the number of 
inflorescences on lateral stolons present 
in February at nodes which emerged 
from terminal buds on main stolons from 
November to January 1984-1985 
Effect of defoliation on the number of 
florets per inflorescence 1984-1985 
Effect of defoliation on the number of 
ovules per ovary 1984-1985 
Effect of defoliation on the number of 
seeds per floret 1984-1985 
�i 
PAGE 
198 
199 
200 
201 
202 
203 
204 
205 
206 
207