Aspects of the agronomy and ecology of Poa trivialis in pastures : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Agronomy at Massey University

Copyright is owned by the Author of the thesis. Permission is given for

a copy to be downloaded by an individual for the purpose of research and

private study only. The thesis may not be reproduced elsewhere without

the permission of the Author.

A S PECT S OF THE AGRONOMY AND ECOLOGY OF POA TRIVIALI S IN PA STURES

A The si s

pre sented i n par t i a l fu l fi lment of the requi rements for the degree of

Doctor of Phi l o s ophy in Agronomy a t Ma s sey Unive r s i ty

Euan Wa l l ace Vartha

1 9 6 9

AC KNOWLEDGEMENT S

My supe rvi s or s , Me s s r s. W . A . Jacque s and

A . E . E s l e r , Forme r l y of Ma s sey Un ive r s i ty and

l a tter l y Prof. B . R . Wa tkin of the Unive r s i ty, and Dr . R . W . Brougham of Gra s s l and s Divi s i on , D . S . I . R . , are thanked for the i r gu idance and cri tici sms o f th i s s tudy .

Acknow l e d ge ment i s made o f guidance from the l a te A . C . Glenday and Mi s s E. Steven son , App l i e d Mathema t i c s Laborator i e s at Pa l me r s ton North and Li nco l n re spective l y , wi th s ta ti s ti c a l a s pec t s .

I am indebted to the l a te Dr . P . D . Sear s and Dr . L. Corki l l , Director s of Gra s s l an d s Divi s i on , D . S . I . R . , for pe rmi s s i on to carry out thi s s tu d y .

TA BLE O F CONTEN T S

I N TR ODUC T I ON .... . ^{. . . .. .} . .. .. ..

R EV I EW O F LITERATURE . . ., " .. ..

Morph o l ogy ^{. . . . . . . . . . .} ..

Re pr o duc tive characte ri s ti c s

Inf luence o f envi ronme n t a l facto r s on growth ( a ) Light ^{. . .} . ^{. .} .. .. .. .. ., "'

( b ) Te mpe ra ture . ^{. .} .. .. ., .. $ ..

( c ) Moi s ture .. "' ..

( d ) Edaphic ^{. . .} . ^{. . ., .. .}

Se a s ona l g r owth pattern . .. .. . .. ., a s e

Oc currence o f Poa trivi a l i s i n pa s ture Source o f s e e d ^{• • •} .. .. .. " .. 0

P a g e 1

4 4 5

5 6 6 6 7 8 1 0 C omparative g rowth o f Poa trivi a l i s and rye gra s s 1 0

E f fe c t o f s own Poa trivi a l i s o n pastu re

produ c t i on . ^{. . . .. ..}

E f fec t s o f c u l tu r a l trea tmen t s on oc cu rrence or growth of Poa trivi a l i s in pa s ture .. ....

EXPERIMENTAL ^{• • • . .} . ^{. . . e "' '"}

Occurrence o f Poa trivi a l i s i n the fie l d

Gr ow th o f P o a trivia l i s and pe renni a l rye g ra s s s e pa ra te l y and i n c ombi nati on9 both wi th wh i te c l ov e r , unde r c u t ting manageme n t s ^{•• • .. . ..}

The e f fec t s o f frequency and i n tens i ty o f d e fo l i a t i on o n the growth o f Poa trivi a l i s w i th pe renni a l ryegr a s s ^{• • • .. . .}

E f fe c t s o f ni trogen and pho s phate on growth o f Poa triviali s and rye g r a s s i n a s soci a t i on

1 1

1 1

17 17

3 1

4 5

5 3

P a g e Ge rmi n a t i on o f P o a trivi a l i s s e e d ^{·� $} .. '" .. 62 E f fe c t s o f shading on growth o f Poa trivi a l i s 6 6

Signi fic ance o f growth form o f Poa trivi a li s

in i n te r spec i fi c c ompe t i ti on <> • $ "' <I> ., 8 5 G ENERAL D I SCUS S ION AND CONCLU S I ON Ss.,., ^{"' ...} 1 0 5

R EFERENCES .. .. '" 11 5

Fi gu re 1

Fi gure 2

F i gure 3

Fi gure 4

Fi gure 5

F i gure 6

F i gure 7 F i gure 8 F i gure 9

F i gure 1 0 F i gu r e 1 1 F i gu r e 1 2

F i gure 1 3

F i gure 14

LI ST O F FIGURE S

Bo tanic a l c ompo s i t i on o f grazed rye gra s s pas ture a t Man a tuke 9 G i s borne ^{e • • e • � � e � ee •} Re l a t i o n s h i p between pe rcentage o f Poa t r ivi a l i s and rye g r a s s in farm pa s ture s ^{· · � • •• · · � � · ·} Re l a t i onsh i p be tween perc e n tage o f Poa tr i v i a l i s and wh i te c l ove r i n farm pa s ture s

R e l a ti o n sh i p b e tween pe rc e n tage o f Poa trivi a l i s and other u n s own s pe c i e s in farm pa stur e s ^{.. � .} . ^{.. ..}

e "' <>

. ^{.. ..}

.. .. ..

. ^{.. ..}

Botan i c a l c ompo s i t i on o f Poa trivi a l i s 9 ryegra s s and mix e d sward s

-un

_{der hard}

and l ax cutting. . .. ^{6 • • .. . ..}

Percen tage o f Poa trivi a l i s in herbage from P o a trivi

aTi

s-ryegra s s sward s under

-cll

tting trea tmen t s ^{• • • . � .. � .. ..}

Ge rmi n a t i on o f Poa trivi a l i s seed i n t h e fi e l d ^{•• G a e e ee • Q � e e • • •8 8} T o t a l p l an t we i gh t o f Poa trivi a l i s and ryegra s s under shade trea tmen t s .,.,., Le a f 9 s tem and r o o t dry we i gh t o f Poa trivi a l i s and ryegra s s p l an t s under shade trea tmen t s ^{• • .. .. .. • • ., ..} . ^., . Le a f area o f Poa trivi a l i s and ryegr a s s p l a n t s under shade t re a tme n t s ^... . ^{.. • •} Ti l l e r number s o f Poa trivi a lis and rye gra s s p l an t s under shade trea tme n ts Re l ative g rowth r a t e s o f Poa trivi a l i s and rye gra s s p l an t s under

-sh

_ade

t r e a tmen t se . . ^{•• • • •• s •• • • •} S pe c i fic l e a f area o f Poa tr iv ia l i s and ryegra s s p l a n t s under shade trea tmen t s . . . ^{•• •} .^.. . ^{••s ... .} Le a f w e i g h t r a t i o o f Poa trivi a l i s and rye g r a s s p l an t s under shade tre a tmen t s... e 0 <> � ., .. ^{..... ••e}

. .. .

•••

Page

9

1 8

1 9

2 0

4 2

5 1 6 4 6 8

7 0 7 4 7 5

7 8

8 0

8 1

Figu re 1 5 Fi gure 1 6

Fi gure 1 7

Fi gure 1 8

Fi gure 1 9

I l lu s t r a t i on o f semi-e rec t and

s e mi-pro s tr a te forms of Poa t r i v i a l i s Dry ma tter yi eld from 1 s i mu l a te d1 swar d s o f r ye gr a s s wi th s e mi-ere c t Poa trivi a l i s ^{�•a -��} & e $ · · �

Dry matter yi e l d from 1 s i mu l a t e d1 swar d s o f rye g r a s s and semi-pro s ­ trate Poa trivia l i s ^{e• • � a e &s �} Ti l l e r numbers from 1simu l a ted1 swar d s o f rye gra s s wi th semi-e r e c t P o a trivi a l i s ^{· � • $ & & ee & · � ·} Ti l l e r numbe r s from ' s imula ted '

swar d s o f rye gra s s wi th semi-pr o s tr a te

Page 9 5

9 6

97

99

Poa trivi ali s ^{��a � & a a �0 �a • $0 G} 1 0 0