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A S TUDY O F C OMPE T I T I VE RELAT I O N S H IPS BETWEEN
S E LECTED G RA S S E S D U R I NG THE E S TA B L I S HMENT PHAS E
A THESIS
PRE SENTED IN P ARTIAL FULFIL MENT OF THE REQUIREMENT S
FOR THE DE GREE
OF
DOCTOR OF PHILOSOPHY
AT
M A S SEY UNIVER SITY
UPATI S SA RA VINDRANATH S ANGAKKARA
19 8 3
AB S TRAC T
Comp e t i t i on has been i d en t i f ied as a maj or phenomenon a f f e c t ing the grow t h of p a s t ure sp ecies in mixtures . Thus a s tudy comp r i s ing o f f i e l d , gla sshous e and c lima te lab ora t o ry experiments was conduc t e d t o iden t i f y the oc cur rence and t he nature o f comp e t i t ive relat ionships during es t ab l i shmen t and early growth o f t hree common gra ss spec ies used in the p as t or al indu s t ry o f New Zeal and . S imp l e mod e l s of compe t i t ive s i tuations we re c re a t ed by the use of the de Wi t rep lace
ment s e r i e s p r i ncip l e , in order t o carry out the se s tudies .
The re su l t s of a l l experiments demonstrated tha t t he s e le c t e d s p e c i e s , name ly p er ennial ryeg ra s s (Lol i um perenne L . ) "Gra s s lands Nui " ; pra i r i e grass (Brom us ca tha r ti cus Vah l) "Gra s s lands Ma tua"
and c o cksfoo t (Da c t yl i s glomera ta L . ) "Gra s s lands Apanui " comp e t e f o r t h e same env ironmen tal r e sources . The compe t i t ive a b i l i t ies o f t h e three spec i e s were in t h e order o f p r a i r i e gra s s > ryegra s s >
co cks foo t . The superior per formance of the more comp e t i t ive spec i e s when compared w i th i t s monocul ture was a s s o c i a ted wi th a co rresponding prop o r t ional de crease in the perf ormance o f t he weaker species in a mixtur e . These relat ionships we re observed wi thin 3-4 weeks a f ter p lan t ing and d i d no t a l t e r under the adop t ed experimen t a l cond i t ions .
In addi t i o n , t he f i eld exp e r imen t i ll us t ra ted tha t t hese re lat ions h i p s were p e r s i s t an t in t h e se cond year , under a n in f requent cut t ing
reg ime , a l t hough seasona l growth pat terns of the three spec i e s we re i den t i f i e d .
Ini tia l and sub s equent p lant s i ze had a de t ermin i s t i c e f fe c t o n t he resp e c t ive compe t i t ive ab i l i t i es o f the selec ted gra s s e s . Thi s was as s i s t e d by their growt h pat terns and earli er germina t i on o f t h e more c omp e t i t ive spec i e s . Seed cha rac ters a lso showed a p o s i t ive relat ionship wi t h the p lant s iz e and c ompe t i t ive ab i l i t ie s o f t he s e le c t e d gra sses .
Y i e lds o f t he mixtur e s lay be tween those o f t he respe c t ive monoc u l t ures in a l l exp er iment s , irrespe c t ive of s easonal growth pa t t er r�o f the species . S imulated spring and autumn t emp e ra tures
i i
i i i w i t h in the c limate lab o rator ies d i d no t change the pat tern o f y ield or t he c omp e t i t ive ab i l i t ies and relat ionsh ips of these three s p e c ies .
Evaluat ion o f the e f fe c t s o f compe t i t ion on the growth of ind ividual p l ants of t hese spec ie s when grown in mix tures revealed t h a t both t i ller appearance rate and to a greater ex tent the rate of l e a f appearance on the main s tem in all spec ies were a f f ec t ed b y c omp e t i t ion during early growth . These e f fe c t s were as sociated with t he d ry mat t e r accumu l a t ion p att er�s o f t he s e l e c t e d spec ie s in mixtures .
Roo t compet i t ion b e gan earlier and had a grea t e r impac t on the overall comp e t i t ive relat ionsh ips b etween the s e l e c ted species t han shoot compe t i t ion . Thi s was a t t r ibuted to the ear l i er and greater i n terminglin g of the root s y s t ems than shoot s y s t ems . Evaluat ion of the root growth o f spec ie s both as s ingle p lant s and in mix tures support e d this conclus ion . However , the me chanisms of root comp e t i t ion were not eluc idated .
In order t o ident i fy the pas ture es tab l i shment prac t i ces o f f a rmers and thereby relate the resul t s o f these s tudies t o the p r a c t ical s i tuation , a survey was carr ied out among farmers in c en t ral New Zealand . The results h igh l igh ted that farmers use s eed mixtures cont aining 2-4 gras ses to e s t ab l ish their pas tures . The grasses s e l e c ted for th i s s t udy were shown to be those mo s t commonly used by farmers .
The result s of the exper imen t s o f this s tudy are di scussed in relat ion to the pas t o ra l industry o f New Zealand .
iv ACKNO��EDGEMENTS
I wish to exp r e s s my s incere grat i tude to my supervisors
Profe s s or B . R . Wa t k in (Head , Department o f Agronomy) and Mr E. Rob er t s (Senior Lec turer , Depar tment o f Agronomy) f o r the i r advice , encourage
men t , h e l p ful cr i t i c i sm and as s i s t ance duri ng the course of this s tudy and p reparat ion of t h i s manuscrip t . The i r gu idance has been invaluab le
in all aspec t s . Acknowledgement is also made o f the as s i s t ance and advi c e extended by Mr P . N . P . Mat thews (Le c turer , Department of
Agronomy) , espe c i a l l y during the f ield t r i a l . Gra t i t ude i s expressed to
Mr G . C . Arno l d (Depar tment of Mathema t ics and S t a t i s t i c s , Massey Unive r s i t y) ; Dr V.J. Thomas (App l ied Mathemat i c s Divis ion , D . S . I . R .) and M r D . H . B . Es s l emont (Market Re search Centre , Mas s e y Un ive r s i t y) for their advice and ass i s t ance w i th s ta t i s t i c a l analys i s of the exper iment s and survey .
Mr I . J . Warr i n g t on , Dr R . M . Has lemore and the members o f s ta f f o f the Con t ro l led C l imate Labora t o r i e s , P lant Physio logy
D ivis ion , D . S . I . R . for their coopera t ion and a s s i s t ance during exp e r iment s i n the c l imate labora t o r i e s .
D r M . J . H i l l , f o r provid ing faci l i t ie s a t the Seed Te chnology Centre , Massey Univer s i t y .
Mr T . J . Lynch and other f ield techni c ian s o f the Agronomy Depar tment f o r their ass is tance in cond u c t ing the f i e ld t r i a l .
D r W . Har r i s (ex Grass lands Divis ion , Current ly Dire c t o r , B o tany Div i s ion , D . S . I . R .) and Dr D . R . S co t t e r (Department o f S o i l S c ience , Mas sey Uni versity) for thei r helpful d i s cuss ions .
The s t a f f and graduat e s tudents o f the Agronomy Depar tment for t heir d iscuss ions , as s is tance and c r i t i c i sm .
Mrs J . Cave for her careful typing o f t h i s manuscript and o t her asso c i ated repor t s dur ing the c o urse of this s tudy , and Mr G . Halligan for p reparing the i l l us t rat ions .
The award o f a Commonwealth Scholarship by the Univers i t y Grant s Commi t t e e , New Zealand for the und e r t aking o f this s tudy i s gre a t l y apprec i a t ed . Acknowledgement i s made t o Massey Unive r s i t y for the Graduate S t udy Award i n 1983.
F ina l ly , gra t i tude i s expressed to my parents and bro ther for the i r unders tanding and p a t ience during t he period of s tudy .
V
TABLE OF CONTENTS
Ab s tr a c t
Acknowledgements Tab le o f Cont ent s
L i s t o f T ab le s L i s t o f F igures Lis t o f P la t e s L i s t o f Append ices
CHAPTER 1 . 1 . 1 1 . 2
CHAPTER 2 . 2 . 1 2 . 2 2 . 3
INTRODUCT ION AND OBJECTIVES Int roduct ion
Ob j e c t ives
LITERATURE REVI EW Int roduc t ion
De f i n i t ion of p lant c omp e t i t ion
Interact ive relat i onsh i rB in grass land s 2 . 3 . 1 Plant comp e t i t ion
2 . 3 . 2 Allelopathy 2 . 3 . 3 Gene ral Comment s
2 . 4 Charac t ers as s o c i ated wi th comp e t i t ive ab i l i ty in herb age species
2 . 4 . 1 Seed charac t e r is t ic s 2 . 4 . 2 Germinat ion
2 . 4 . 3 Seedling growth
2 . 4 . 4 General considerat ions
2 . 5 Envi ronmen tal f ac to r s a f fec t ing comp e t i t ive a s s o c i a t ions in herb age p lant s
2 . 5 . 1 "Supply f a c t o r s " a f f e c t ing comp e t i t ion b etween herbage p lan t s
i i
iv vi
X
x iv xvi xvi i
1 1 4
7 7 8 11 1 1 1 7 1 8
1 9 2 1 24 25 30
3 1
3 2 2 . 5 . 2 " Cond i t ioning fac tors "af f e c t ing comp e t i t ion
be tween herb age p lan t s 3 9
4 4 2 . 5 . 3 General cons iderat ions
2 . 6 Nat ure o f comp e t i t ion w ithin herbage asso c i a t ions 45 2 . 6 . 1 Compe t i t ion b e tween sho o t sys t ems of
herbage mixtures
2 . 6 . 2 Compe t i t ion b etween root systems o f herb age species
2 . 6 . 3 Interact io mb e tween shoot and roo t comp e t i t ion
4 6
4 7
53
2 . 7
2 . 8
CHAPTER 3 .
3 . 1
Measurement o f p lant compe t it ion
2 . 7 . 1 Exp e r iment a l designs for s tudying p lant comp e t it ion
2 . 7 . 2 Me thods o f ana ly s ing p lan t compe t it ion 2 . 7 . 3 The de Hit model
Conclusion
COMPETITIVE EFFECTS ON PLANT GRm.JTH AND THE Y I ELD OF GRASS MIXTURES DURING THE ESTABLISHMENT PHAS E .
General Introduc t ion
3 . 2 Experiment 1. A f ield s t udy on the e f f e c t s o f comp e t it ion on p lan t per formance and the y ie l d o f b inary mixtures o f g r a s s species dur ing the estab lishme nt phase from seed , and sub sequent growth o f the es tab l ished swards . 3 . 2 . 1 Int rodu c t ion
3 . 2 . 2 Experimental pro cedure 3 . 2 . 3 Re su l t s
3 . 2 . 4 Discuss ion 3 . 2 . 5 Conc lus ions
3 . 3 Experiment 2. A s tudy on the e f f e c t s o f
competit ion on p l an t p e r f o rmance and t h e y ield of b inary mixtures o f gras s species dur ing the es tablishment phase from seedlings of the same age
3 . 3 . 1 Int roduc t ion
3 . 3 . 2 Exp e r imental procedure 3 . 3 . 3 Re sul t s
3 . 3 . 4 Discus s ion 3 . 2 . 5 Conclus ions
3 . 4 Experiment 3 . A s tudy on the e f fe c t s o f
comp e t it ion o n p lant p e r formance and the y ie l d o f b inary mixtures o f gras s s p e c ies durin g the e s t ab lishment phase f r om s eed l ings of s imilar growth s tage , and t he e f fect of t emperature on the ir r e l a t ionship s .
3 . 4 . 1 Int rodu c t ion
3 . 4 . 2 Expe r iment a l procedure 3 . 4 . 3 Re su l t s
5 6
5 6 6 0 6 4 7 1
7 3 7 3
7 5 7 5 7 6 8 1 1 0 2 1 0 7
1 0 8 1 08 1 0 8 1 1 0 1 2 2 1 2 4
1 2 5 1 25 1 2 5 1 2 8
3 . 5
3 . 4 . 4 D iscuss ion 3 . 4 . 5 Conc lus ion Conclud ing Remarks
CHAPTER 4 . AN EVALUATION OF THE COMPETITIVE EFFECTS ON THE DEVELOPMENT AND EARLY GROWTH OF INDIVIDUAL GRASS PLANTS GROWING IN BINARY MIXTURES
4 . 1 Introduct ion
4 . 2 Exper imen t a l pro cedure 4 . 3 Resul t s
4 . 4 D i s cuss ion 4 . 5 Conc lusions
CHAPTER 5 . A STUDY ON THE RELATIVE IMPORTANCE OF SHOOT AND ROOT COMPETITION I N DETERMINING THE OVERALL COMPETITIVE RELATI ONSHIPS IN BINARY MIXTURES OF GRASS SPEC I ES
5 . 1 Introduct ion
5 . 2 Experime n t a l p r o cedure 5 . 3 Re su l t s
5 . 4 D iscuss ion 5 . 5 Conclus ions
CHAPTER 6 . S EED AND PLANT GRO�ITH CHARACTERISTICS S PEC IES DURING THE SEEDLING PHAS E 6 . 1 Int roduct i on
6 . 2 Exper imen t a l procedure 6 . 3 Re su l t s
6 . 4 Discuss ion 6 . 5 Conc lusions
OF GRAS S
CHAPTER 7 . GRASS SPECIES U SED AND PASTURE ESTABLISHMENT I N CENTRAL NEW Z EALAND
7 . 1 Introduct ion 7 . 2 Methodology 7 . 3 Results
7 . 4 D i scuss ion and conclus ions
CHAPTER 8 . GENERAL OVERVIEW AND CONCLUS IONS
8 . 1 Compet i t ion between "Grass lands Nui " perenn i al ryegras s , "Grass lands Matua" prairie grass and
"Gras slands Apanui" cocksfoo t
1 40 1 4 2 1 4 3
1 4 5 1 4 5 1 4 6 1 4 9 1 6 6 1 70
1 7 1 1 7 1 1 7 2 1 7 4 1 8 3 1 8 5
1 8 7 1 88 1 90 1 9 9 200
2 0 2 2 0 2 202 2 05 2 1 3
2 1 6
2 1 6
8 . 2 Response o f individual p lant s t o compe t i t ive s t res s during e s t ab l ishment and early growth 8 . 3 Roo t and shoo t comp e t i t ion be tween the s e l e c ted
8 . 4
grass spe c ies
Species charac ter is t ic s a f fect ing compe t i t ive ab i l i ty dur ing e s t ab l ishment and early grow t h 8 . 5 Prac t ic a l imp l icat ions o f the experiments
8 . 6
Append ices
B i b l iography
to pas t ure e s t ab l i shment prac t ices of New Zea land f a rmers
Conc lus ions
2 2 2
2 2 3
2 2 5
2 2 6 2 3 0
23 3
2 5 4
LIS T OF TABLES
CHAPTER 2
Tab le 2 . 1 The inter a c t ive proce s s o f comp e t i t ion be tween r o o t and shoo t sys tems o f herbage
p l an t s (Donald , 1 9 S8) . S S
CHAPTER 3
Tab le 3 . 1 Me teorolo g ical measurements , D . S . I . R . -
Palme r s ton No rth . 8 1
Tab le 3 . 2 Time o f emergence o f species (days ) 82 Tab l e 3 . 3 P lant coun t s o f species taken 28 days af ter
sowing (No. p lan t s per 0 . 1m2 ) 82
Tab le 3 . 4 Mean t i l le r numbers per p lant of s p e c i e s grown in m ixtures and monocul tures
during ear ly growth 8S
Tab le 3 . S Mean weigh t s of shoo t s (g) per p lant of species gr own in mixtures and monocul tures
dur ing early growth 8 7
Tab le 3 . 6 Dry ma t t e r ( g /m2 ) o f grass mixtures and monocu l tures at each harves t dur ing the e s t ab l i shment phase
Tab le 3 . 7 Dry mat te r yields of grass mixtures and monocul tures at each harves t dur ing the
second year
Tab l e 3 . 8 Re lat ive c rowd ing coe f f i c ient s of b inary comb inat i ons at every harves t dur i ng the
88
9 1
second y ea r . 9 S
Tab l e 3 . 9 Re lat ive y ield t o t a l s b ased on veg e t a t ive charac ters o f t he s pe c i es over the e s t ab l ish
ment phas e . 9 7
Tab l e 3 . 1 0 Re lat ive y ield t o t a l s b as ed o n y ie l d
compone nt s 9 8
Tab l e 3 . 1 1 Aggres s ivi ty indices o f the more aggress ive spec ies b as ed on p lant characters in the
e s t ab l ishment phase 1 0 0
Tab l e 3 . 1 2 Mean t il l e r number p e r p lant o f t h e gras s spec ies dur ing early growth and p r ior t o every harve s t , when grown in mixtures and monocul tur e s
Tab l e 3 . 1 3 Mean sho o t weight per p lant ( g) o f the grass species a t ' every harve s t , whe n grown
1 1 1
in mixtures and monoculture s . 1 1 2 Tab le 3 . 1 4 Leaf area (cm2 ) per p lant of the gras s
spec ies a t every harves t 1 1 3
Tab le 3 . 1 5 Dry ma t te r yields (g /box) of mixtures
and monocul tures a t each harves t 1 1 6 Tab le 3 . 1 6 Rel a t ive y i e ld t o tals based on veg e t a t ive
char ac t e r s of the 3 species - Experimen t 2 . 1 1 9 Tab le 3 . 1 7 Re l a t ive y ield t o t als based on yield
component s at each harves t - Exp e r iment 2 . 1 1 9 Tab le 3 . 1 8 Aggre s s iv i t y ind ices of the more aggre s s ive
spec ies b ased on the vege t a t ive char a c t ers
of the 3 species - Experiment 2 . 1 2 1 Tab le 3 . 1 9 Mean t i l l e r numb e r s per plant o f the gras s
spe c ies a t high and low t emperatures , measured a t an average light intercept ion of 5 0% and 95% across all treatment s Tab le 3 . 20 Mean leaf area per p lant ( cm2 ) o f the 3
grass s p e c ies a t every harves t for the two t empe r ature regimes
Tab le 3 . 2 1 Mean shoot weight (g p lan t-1 D . M . ) o f the gras s spec ies a t every harvest for t he two temperature regimes
Tab le 3 . 2 2 Dry mat te r yields (g po t - 1 ) o f the micro swards for the two t emperature regimes Tab le 3 . 2 3 Rel a t ive y ie ld t o tals b ased on vege t at ive
cha r ac t e r s of the 3 grass s p e c ies at the two t emperature reg imes
Tab le 3 . 24 Rel a t ive y ield t o t a l s b ased on y ie ld compon
ent s at every h arves t for the two t emp eratur e regimes
Tab le 3 . 25 Aggres s iv i t y indices of the more aggr e s s ive spe c i e s b as ed on t he vege t a t ive charac t e r s of the g r a s s spec ies a t the two t emp e r ature regime s .
C HAPTER 4
Tab le 4 . 1 Mean p l an t hei gh t (cm) of s pe c ies in mixt ures and monocul tures
Tab l e 4 . 2 Mea n root length ( cm) of s p e c ies in mixt ures a nd mono cultures
1 30
1 3 2
1 34
1 3 6
1 3 7
1 39
1 5 0
1 5 1
Tab le 4 . 3 Mean leaf area (cm2) o f species in mixtures and monocultures
Tab le 4 . 4 Mean shoo t we i gh t (g) of species in mixtures and monocul tures
Tab le 4 . 5 Mean root weight (g) per p lant of s p e c i e s i n mixtures and monocul tures
Tab le 4 . 6 Leaf and t i ller app earance r a t es o f species growing in mixtures and monocultures dur ing
1 5 2
1 5 3
1 5 4
early growth 1 5 7
Tab le 4 . 7 Dry mat te r ac cumu l a t ion rates o f shoo t s and roo t s of spec ies grown in mixtures and
monocultures during early growth 1 60 Tab le 4. 8 Re lat ive y ield t o t als o f species comb ina t-
ions b ased on sho o t and root weigh t s at
eve ry harves t 1 62
Tab le 4 . 9 Aggre s s iv i ty based on shoot and roo t we i gh t
CHAPTER 5
per p l ant o f the more aggres s ive spec ie s growing i n mixtures and monocultures
Tab le 5 . 1 Mean t i ller numbers per plan t of species grown in d if ferent interspec i f ic compe t i t ive s i tuat ions
Tab l e 5 . 2 Mean s hoo t weigh t per p lant (g DM) o f species grown i n d i f ferent interspec i f ic
1 63
1 7 5
compe t i t ive s i tuat ions 1 7 6
Tab le 5 . 3 Mean root we i gh t per p lan t (g DM) o f spe c ies grown in d i f f erent interspe c i f i c compe t i t ive s i tuat ions
Tab le 5 . 4 Rel a t ive yield t o t al based on shoot we ights and root weigh t s of species
C HAPTER 6
Tab l e 6 . 1 1 000 seed we igh t s (g) o f ryegras s , prairie grass and cocksfoot
Tab l e 6 . 2 The weigh t s o f seeds and s eed compone n t s
1 7 8
1 80
1 9 0
o f ryegrass , prairie grass and cocks foo t 1 9 0 Tab l e 6 . 3 Total leng th o f a l l root s (m) and p a t te rn
o f root length d i s t r ibut ion o f ryegras s , prai r i e grass and cocks foot w i th i n the
root ing medium 1 9 5
Tab le 6 . 4 Dry weight (mg) o f roo t s and pat t e rn o f root weight d i s t r ibut ion o f ryegras s , prairie grass and cocks foot within the roo t ing medium .
Tab le 6 . 5 Dry we i gh t o f shoo ts (mg per p l an t ) o f ryegr as s , prairie grass and cocks foot during early growth
Tab le 6 . 6 Dry mat te r ac cumulat ion rates of ryegras s , prair ie gra s s and cocks foot during early
1 9 6
1 9 7
growth 1 9 8
CHAPTER 7
Tab le 7 . 1 Re sponse rate o f que s t ionnaires for e ach
region 204
Tab le 7 . 2 The p ercentage of tractorab l e land in
each type o f farm 2 0 5
Tab le 7 .3 Te chniques u s e d and to be used by f armers
to e s t ab l i sh pas tures (% use of each me thod) 2 0 7 Tab le 7 . 4 Pas ture mixtures sown and to b e s own ( % o f
a l l f armers us ing each type o f mix) 208 Tab le 7 . 5 Percentage o f f a rmers us ing a par t i cu lar
ryegrass cult ivar as the maj or component
in t he seed mixture 2 1 1
Tab l e 7 . 6 Factors a s s i s t ing f armers in s e l e c t ion
o f p a s ture species (% of f armers surveyed ) 2 1 2 CHAPTER 8
Tab le 8 . 1 Dry ma t te r accumulat ion rates based on sho o t weigh t s of ryegras s , prairie grass and cocksfoot a t 2 , 4 , 6 and 8 weeks a f ter
p l an t ing ( adap t e d f rom Exp e r iment Lf) 2 2 6 App e ndix 9
Tab le A9 .1 Sho o t eme rgence o f ryegrass , prairie gras s and cocks foo t whe n germinated in b inary comb inat ions
Tab le A9 . 2 Roo t l ength ( cm) of species growing in mixtures and monocu l t ures
2 4 5
2 4 6
LIST OF FIGURES
CHAPTER 2
F i gure 2 . 1 Relat ionsh ips be tween var ious concep t s o f plan t interrelat ionships based o n Tinnin
( 1 9 7 2 ) ; Braakhekke ( 1 9 80)
Figure 2 . 2 Rep l acement diagrams represent ing comp e t i t ive 1 0
relat ionships b e tween two component s p e c i e s 6 4a F igure 2 . 3 Re lat ive Yield To t als and corresponding
replacement d iagrams illus trat ing d i f f erent
comp e t i t ive s i tuat ions ( Braakhekke , 1 9 80) 68 CHAPTER 3
Figure 3 . 1 Po i n t ana lysis (numb er o f h i t s of each spec ies) along a f ixed t ransect across a l l
treatmen ts 83
Figure 3 . 2 Cumulat ive dry mat ter y ields ( g .m- 2 ) o f gra s s mixtures and monocultures during the e s t ab l i shmen t phase
F i gure 3 . 3 Cumu lat ive dry mat ter y ie lds ( g . m-2 ) o f gra s s mixtures and monocul ture s during the second year
F i gure 3 . 4 Rep l acemen t di agrams based on dry mat ter y i e lds ( g . m- 2 ) o f species components in gr ass mixtures and mono cultures and t o t a l y ields for 3 harves t s during the es tab l ishment year .
Figure 3 . 5 Rep lacement diagrams based on dry mat ter yields ( g . m- 2 ) of spec ies in mixtures and monocul tures and total y i e ld a t every harve s t dur ing the sec ond year
Figure 3 . 6 Plant ing arrangemen t of two species mixtures ac cord ing t o the rep lac ement p rinc iple . F i gure 3 . 7 Rep lacement d iagrams b ased on dry mat ter
y i e ld s ( g /box) of spec ies componen t s in grass mixtures and monocul tures and t o ta l y ields at each harves t
F i gure 3 . 8 Rep l acement d iagrams b ased on dry ma t ter y i e lds ( g . po t-2 ) of species componen t s in grass mixtures and t o t al y i e lds a t each harves t f o r the h i gh t emperature and l ow t emp er at ur e regimes
89
9 2
9 4
9 4a
1 0 9 a
1 1 8
1 3 5
CHAPTER
C HAPTER 4
Figure 4. 1 The rate of t o t a l dry mat ter accumu l a t ion per p lant o f ryegras s , prairie gras s and cocksfoo t , measured a t weekly inte rvals and a t 95% l ight intercep t ion
5
Figure 5 . 1 Plant ing arrangement s o f two s p ecies mixtures growing in 1 : 1 rat ios
Figure 5 . 2 The comp e t i t ive ab i l i t y o f spec ies
mea sured as aggres s ivity (McGi l c hr i s t and Trenb a th , 1 9 7 1 ) based on s hoot weigh t s o f p lants o f ryegrass , prairie grass and cocks foo t when grown in b inary mixtures under cond i t ions o f full �ompe t i t ion , roo t comp e t i t ion and sho o t comp et i t ion Fi gure 5 . 3 The c omp e t i t ive ab i l i t y o f s p e c ies measured
as aggr e s s iv i ty based on roo t weigh t s o f p lant s o f ryegrass , pra i r ie grass and cocksfoot when grown in b inary mixtures unde r cond i t ions of ful l compe t i t ion , roo t compe t i t ion and shoot comp e t i t ion . C HAPTER 6
F i gure 6 . 1 P lan t h e i gh t and root length ( from base o f p lant t o t ip o f younges t leaf and longe s t roo t ) in ryegras s , prair i e grass and cocksfoot during early growth
Figure 6 . 2 Lea f area per p lant of ryegras s , prairie grass and cocks foot dur ing ear ly growth F i gure 6 . 3 T i l l e r numbers per p lant in ryegras s ,
p r airie grass and cocks f o o t during early growth
C HAPTER 7
F i gure 7 . 1 A map of New Zealand i l lu s t r a t ing the s t a t i s t ical areas s e le c t ed for the survey
( shaded area) .
1 6 5
1 7 2a
1 8 1
1 8 2
1 9 1
1 9 2
1 9 3
2 0 3 a .
P l a t e 1 . P l a t e 2 .
P l a t e 3 .
Plate 4 .
P la t e 5 . Plate 6 .
P la t e 7 .
Plate 8 .
LIST OF PLATES
A general v iew o f the f ield t r ial (Expe r iment 1 ) 7 6a A gener a l view o f the box exp e r iment
(Exper iment 2) 1 08a
The layout of the experiment in the controlled env ironmen t rooms
Exper iment 4 - The general layout within the c l imate laboratory
Tagging of t i l lers
Exp e r iment 6 - Par t i t ion ing of s �oot and roo t c omp e t i t ion
The s tudy of ind ividual p l an t s in a heated glas shouse
Layou t wi thin the germinat ion c ab ine t
1 2 7a
1 4 7a 1 48a
1 7 3a
1 88a 2 4 3 a
App endix 1 .
Appendix 2A .
App endix 2B .
Appendix 3 .
App endix 4 .
App end ix 5 .
App end ix 6 .
App end ix 7 .
Appendix 8.
App endix 9 .
LIST OF APPENDICE S
The mathema t ical mode l to ca lculate
the Re lat ive Crowding Coef f ic ients (de Wit , 1 9 6 0 )
S o i l mo is ture tens ion ( Bars) w i thin t h e top 20 cm layer o f s o i l , and the weekly r a in f a l l f igures (mon i t ored a t t h e D . S . I . R . ,
Palmer s t on North) over the exper imen t a l period
Comp u t ed s o i l wa ter s torage o f the exper iment a l s i t e over t h e expe rimental p e r i o d using the
2 3 3
2 3 5
me thod o f S c o t ter e t al . ( 1 9 7 9 a , b ) . 2 3 6
Mean p l an t he i ght ( cm) o f s p e c ie s grown i n mixture s and in monocultures dur ing early grow th
Mean d e p th of roo ts ( cm) per p lant grown in mixtures and in monocult ure s dur ing early growth
Mean we i ght ( g) of roo t s of spec ies grown in
2 3 7
2 3 8
mixt ures and in monocultures dur ing e arly growth 2 3 9
Mean p lant he i gh t ( cm) o f t h e grass species dur ing early growth and prior t o every harve s t , when grown in mixtures and in monocul tures
Mean p l an t he i ght ( cm) of the grass species a t h igh and low temperature s , measured at an ave rage l ight intercept ion o f 5 0 % and 9 5 % acros s a l l t r ea tment s
C l a s s ification o f t illers ( Langer , 1 9 7 2 )
Shoo t emergence and root development o f ryegras s , prairie grass and cocks foot when germinated in binary combinat ions
240
2 4 1 2 4 2
2 43 Appendix l OA . Let te r accompanying the ques t ionnaire to farmers 248
App endix l OB. Ques t io nnaire sent to farmer s for the survey on
the use of pas ture species i n Central New Zea land 2 49
