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L. nmltiflonui1)
linn! P
in p
,ell
of
o:f
eml
in the
by
'Jv{n~y
eoln ColI
1964
fl! 1
1
t
L
1
I
4
1
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1
on.
co () f
1
18
.1' 1
III
4·J
of ry
( 1)
1
(2)
1.
o:f
1.\
1
p
(3)
1
s
ees
p
1
(
f
1
11
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1~
0
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It
]
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i
11 e
1
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i'
fj
of 11
t"
In
.
f~n~jl
,
t
:1.
"
"
.1
1
()
1
s of
1.
.1
"
"
."
.
cmH,E
1 D t.i OIlS
p
t~X
i
~)
phyll 1
e
0:1."
e
tu Ie
fox' n:.l
g r [ii, S
8. t
tin' eel t=lV e 1 S
at
of 1 i
.....
ex for H.I
88
I]
thro~
t
GB
S niltl Bu. t t' s
level~
of Ii
t
eTaturo, relative
1.
on • .
Sf;
s of
at thX'(\e 1
harvest occasions
~
ntio:n
..
t,
4.
t
ra
o:f
0
64
t 8t
lysi 8
0
l' vnri 1'me(5
0 of
64
,1:Tt (l
. 50
"Hilt
ryogra~H3
t
s at three levels of Ii
i ty •
at 0
9.
10.
•
ysts of
8,
an
j
47
tt 11 el's/pl,a:n t
area indices of
in
0
64
leaves/pl.rtnt
7.
0
nce of dead materiel dry
of
().
• • •
• • •
~
~
G
e
,
e
anee of loaf area
a
_
•
•
•
0
~
&
•
$
t~ ~~
t)~
lees
64
1H11 vi Ihwl
area
64
alysis of varianoe of leaf chlorophyll,
tom chlorophyll and
{I
64
•
g
59
11.
ai chlorophyll, stem chloroohyll and
2
totrd chlorophyll (C.I.)(g./m. ) of ryes and prairie grass
of
iation
ehloro
six harvest occasions • • •
1 inrtex on si
e
60
e
63
harvest
oeeas:inns
13.
crm:tnl
'J
o]n of leuf chlorophyll (llIg./{lm."'
of leaf) of
under three leve].s of incident
~n~
at six harvest
14. Annlysis of
occ~sionB
•
00
anoe of leaf chlo
If
4)
1
'J
concentration (mg./rJm.'" of le;:d) cit d
64 • •
15 ~
• • •
e
€I
$
•
mum (lrOr;
Uei 1:1
•
16.
(,4
•
I'8te, op
tins
• •
fi5
mum 1
.....
17.
c:r'op
•
.
• • • • 71
..
18.
nu. le;r:1f chlo
Il
(
<)
n·r ] . E'Af')
'I.,
'<:'__
. , ll"'l
l , ,.,
1 cone
():P
.•.
',;:C)lrl(~
.
.. '
Uo:n
c1.. ,O'V"'.~-'>R
,. . . .
~
from n
wei
t
1ncrementAlnit wei
t
Tll
t of
oro-
)
phyll/nni t
Fl
(19fl O)) • • •
crop
8f5
1
I
of recent
reasons, a great
on of
reotNl
been the
of au
ant
in
1
s
of i
Ii
t
01:1
011
f Ii
1
t
is
tlH~
of
on
i
t. as a
e 1
of
s
u
a.bly
Sl'!.T :faoe.
11 be
EHve£1 Btl b s e~
leaf area,
is an
reot measure
photosynthe
to
bf'!en fOlmd
rate of
e
red. to
es
a
011
va
on.
eld of a
of
t
01
di
avai I.B,bIe
of
of 1
yield IJer
s
cuI tural
a:no growth
OD,
n
p
ation at
d
II
the level
it of
lJart,j.oulnr
2
plant population.
Growth halli t i s impU_cated. lJecause of
the effect of orientation and distribution of plant parts
on light penetration into a pasture or cropo
The practical impl!
on of these concepts is that
a pasture sward or forage crop might be maintained at its
maximum growth rate, even with seasonal variation in the
level of incident radiation, l)y controlling through
cut~­
ting or grazing the leaf area at optimum values.
III
vi<:1w of the small
experime:n~tal
evidence to support
thesH concepts and disagreement by some worl<ers, two
grasses (short-rotation ryegrass Bnd prairie grass), of
very di.fferent growth hal)it (rate of tillerirlg and leaf
prodnction, ll')af size <'md plant stature) were sr.nm in pure
swards to determjne:(a) wbether each species had an opthmrn leaf area
at which growth rat.e
WlH3
maximal,
(b) whether these optimum len.f areas cha;l.lged wi th
the level of incident radiation,
(0) whether there was a speetes interaction with
the level of incident radiation,
(d) whether the chlorophyll content was a more
direct measure of the size of the photosynthetic
system th.an leaf area and hence more closely
correlated with growth rate and vegetative yield.
3
In addition, reduction of the level of
diation "by 50% and 709~! enables sunnner, spring
and winter light conditions to be simulated.
=
alltumn
Thus,
species responses to seasonal changes in tbe level of
incident radiation can hc evaluated.
, Rl<:VIEW OF THE
on of
to the linli
ve
crea,s
e
of pas
s
become
tor of
centred on the light
•
This review deals with the
1
st between light energy and pI
ion
s
on,
produ
llowing headings:(1) rrhe importance of solar radiation to
e
yi (~ld..
(2) The inter-relationship of leaf areB i
rate and radiation.
(3)
os of chlorophyll concentration
ant tissues.
(1)
OF
t
ewa on
RADIATION
ti
on
fro
(!l.J'U1XU-L
1961, 1963)
5
have emphasized the importance of solar radiation to the
vegetative growth of pastures and crops.
As Donald
states, "the vital relationship in competition for light
is one of physical position of leaves", on both an interand intra-plant basts.
{lnU.
water aod nutrients, solar
radi.ation f!annot be translocated within the plant
only be intercepted and utilized instantaneously.
call.
Because
of this unique featuI'e, the light regime in 'which the
photosynthetically active parts of the plant are placed
controls the level of photosynthates available for incorporation into the plant tissues.
Bohning and Burnside (1956) found. that in sU.n plants
a light intenstty of the order of
~OOO
to 2500 foot-candles
(f.c.) permitted maximum rate of photosynthesis of the
individual leHf (leaf light-s,aturaterl), while shade species were
light~~Hltur,a,ted
at 400 to 1000 f. c.
intensity where respiratory
lo~s
The Itght
equalled photosynthetic
gain of carbohyctrates (the compensation point), was 100
to 150 Lc., for
cies.
SUll
speci('!s
clnd
50 f.c.,
for shade spe-
More recently Besk th and Moss (1963) found closely
analagons light saturattoJtl values for a wide range o:f sun
plants, except for sugar cane, mai ze and
SlUl
flower where
the individual leavBs were not light saturated at light
6
out 10,000
os of
i
leaves is generally
of
at these rela-
low levels of i Ilmnination, it
would not be 1
Ii
saturation
Ii
f.c~
have been
But
1
s, where le.ElVes
it was
01
tie ret
i
Ii.
net
old conditions
., a
saturation light in
s
to-
i
(1963),
while M1111er (1951), as
e level at
ch light s
of
ex
foli
1.3 to 3.7.
or
Db
]
were
.
i
0
on
.. 1
Ison (19
),
on of carbon
t of
i
fl
iflu
liza
800 :t.c.
re
cuI
"J..
t :I
leaf
WCI.S
.~
on of I i
I
nni
on of
ty
su.:n
[OlY>
800 f.c o
,
an
1
cotes was
sugges
t would fHlcur
o:n
)
UH~
mum
t
u mean i
o:f
on
fo1i
WIlson I ...p , (19151
!
19
)
7
teh.ell and
der (1958) showed that the
efficiency of USB of light, as measured by qURn
ty of
tiflslle formed/nn! t qua:n.tity of light energy/uni t of photo~
synthetic leaf tissue i8 highest where the majority of the
fol1 age reeet ves relatively low levels o:f light in tEH1si ty.
th the establishment of thi.s
nciplo of increAB
effioiency of utilization of light by dense foliage, reseax'ch has boen directe{l
tOWi3T{~S
th.B
elucidation o:f
tors
whlch coutrol light penetration into a sw.t'),rd.
From theore
cal considerRtions by Warren
1 S o:n (1960),
IsDn and Britten (]963), Saeki (1960), Monsi
Ver~agen,
and Sa(~lri (1953) and other ,Japanese ·workers, it is app
that light penetration through a crop or pasture :foli
is affected by:(a) Incident light intensity
(b) SIHJ.tial distritHltion of leaves in reI
on to
the incident light
(c) 'rhe optical properties of leaves o
On a macro-scale Black (1954-55) showed that the light
energy reaching the earth's surface (plant surface) varies
del)ending
lJpOn
lati tUde, time of year and atmospheric
conditions.
It is genera.l1y accepted that li.ght
a sward decreases exponentially
teD.si ty wi thin
th depth, roughly accord-
8
ing to 1,ambGrt's I,aw (1Y;:Jrren Wilson 19EiO),
I
= light
I
Tlm~
:=
-KL
I
intensity beneath leaf area index of
L.
I D :=
li~ht
to.
intensity at sward surface.
K
:=
abso
tion coefficient (extinction coefficient)
e
=:
Napierian constant.
lvi th increasing light intensi ty more and more
leaves will be
betlH~en
compensation and saturation {lDint.
Variation in incident light intensity will tbus give rise
to variation in the level of net photosynthesis of a sward
and to seasonal variation in yield.
nle important
tor
determining the amount of foliage a particular plant popu.latian requires for most efficient u
lization of incident
light (maximum net photosynthetic rate of whole foliage) is
the K value.
This
~alue
is
ed by the spatial arrangement
and optical properties of the foliage.
Experimentally, light al)sorption by leaves has been
studied extensively and it is generally concluded that
ahout 30"", of thf~ incident Ii.gilt is reflected and transmi tted and
7o,b
a11sorbed (Gabrielsen 1948; Ilabhleau, French
and Holt 1946;
MOflS
and I-,oomis 1952).
It is evident,
hOlV-
ever, that these values will depend on leaf angle and the
optical properties of the leaves.
9
Watso:n and \'litt.s (1959) emphastzed the import::mce 01:
foliar angle in their comparison of wild and cultivated
1Jeets, and Warren
lson (1960) mnclud.ed that, "in stro:ng
daylight the most efficient utilizatj.on of light will occur
~~en
swards at optimum leaf area index have their lowest
foliage horizontal, and alJIJropriate transttional foliage
angles at intermediate levels."
Optical properti.es have been examined. theoretically
by Verhagen, Wilson and Brttten (1963) from computation of
Saeki's (1960) data.
They criticise Monsi and Saeki (1953)
for assuming that all light falling on a leaf enters it and
suggest that leaves, highly tilted with respect to the In=
coming light, will not only intercept less light than if
they were horizontal, but also that a Im.'ger part of that
i:l'ltercepted wi 11 be refl ected deeper 1.nto the foli age.
On
the basi s of the way in which Ie changes wi th 1 eaf
area irldex, Verhagen, Wilson and Britten (1963) hHve derived
theoretical production equations for four types of foliage:-
(a) Ideal foliage - the average intensity of light
entering a leaf, is the same for any leaf, for
any value of leaf area index.
(b) Best exponential foliage - the foliage has the value
o:f F for maximum production at each total leaf area
index'va.lue.
10
(c) Standard exponential foli
Ii
in
the bottom leaves are at compens
ch, for each possible
point in a foli
of 1
talres
file,
of the two possible
J(
values ..
(d) Exponential foliage
=
the
of
with increase
co
cen
1960~
t
1 COD-
elsen
1961;
t 1946) and the
sward.
in I i
in-
Stern (1962) conc
penetration, the composi
creasi
1i
i
on is altered to longer wavel
cons
on of
incom-
the.
on is here given to the
010
logical changes in individual
lIlO
oed.
the
level of Bolar radiation reachl
er:imentally, shacUl1.g to 0.5 dayl!
ve
eeia
I'a
19
t decreas
Ison 1951a, 1951b; HI
ell 1954; TIl
th
8Ji
b eause
(N.
e.
(R.G.H.) of a wide range of pI
and
(
ex.
i
1
K are leaf
ue
1
s
e:nta
on to leaf
rela
1
n.)
1957).
1
area
tar
8
eOl1.trasting re
This
s
to (1,.
on
0:£ net assi=
R.)
11
as
Ii
t :intenI'd. ty
i
t.
effects of decreas
ty on
t in
Ii
are as follows:-
plant
(
e of
creased
Iler
on and
11er
on in
1
11
, 1
, 1
leaf area to 1
(b) Increas
wei
o
t
ell 1
thi.nner I eaves (
s
8,
ving
; Blackman,
Kernp 1955).
creased root to top wei
(c)
t
rl'rough.ton 19
19
ght in
1'8
0
(
19
1 1954;
1940) •
(
ct 1941;
) e
ons
se
OD,
eI)
on,
dispersion, of leaves)
anrl
in 1
i
lllaximum net pho
pa.st.ure or
ologiN,l
tion of these 8
1
of
strl-
solar radiation, will
the
can
c n:tte per ground area
eve.
s
the
12
(2) 'l'HT5 IWPBR-HgL4.TIONSHIP OF' 1,EftJ,1
AND SOl,AR HAJ)IA'I!ION
th the present knowledge of Ii
s in
reI
t
saud pastures, it seems only
ould. have become
i
,ac(~
area
t.ed as an
t.
the rat.e of dry ma.tter
on of
however, were iUreeted
stlHliEHJ.,
auey and photosynthetic rate of i
e
sol
e
leave
plants and not of crop
the development of the 1
(
son 1
t
) came an increas
area of foliage
it
:i t,
light reI
on ill
cnce on
conse
).
of
e
1
of
II
s
),
This led navidson
some .Japanese workers to
of rate of dry matter
on
leaf areB indexQ
s
Because light interception by a sward is
a s
f
is
ed with increasing leaf area
lowest leaves are just at compensation po
e~
the "optimum leaf area index" (
t.
an
This
13
Monsi 1954; DI3I.vidson and
d 19[i8j Stern amt Donald 19(2),
the "marginal compensation area" (Davidson and Phillip 1958)
and the "cri tical leaf area index" (Broughm,l.; 1958b).
Brougham' s
~I
131'1 tical leaf area index" occnrs when the
liage intercepts 95~ of the incident light.
fo~
Up to this
point apparent photosynthesis and thus rate of dry matter
accumula tion of the whole foliage, increases '!-vi th leaf area
index.
In this thesis
th(~
leaf area index at which crop
growth rate (C.G.R.) is maximal will be termed the "optimum
leaf area index".
Donald (1961, 19(3) maintains that further increases
in leaf area index past the optimum cause a reduction
net assimilation (apparent photosynthesis).
This, he
explains, is due to respiration exceeding photosynthesis
:in leaves below (Jompensatio:n po
t, implying that the
necessary balance of carbohydrates are translocated from
leaves above compensation point, and to rising respiratory
losses through increases in non-photosynthetic plant tissne.
There is, however, no evidence for such translocation of
earhohydrates to senesoing 1 eaves, whi.ch would be in aI::Iposition to the general principle of translocation to active
meristematic centres.
In addition, Williams (1964,a, 1964b)
fOI1.nd that fully expanded leaves export, but do not import
14
1
as
es.
re-
More realistical
of a seneseing leaf would come
s
of its om) d.egenerating
ssnes.
area
It would seem that optimum 1
1
are
ex at
i
eh there is an
on of leaf area
foliage.
sis of
c
on coe
ci
leaf area i
on
light
is
If
110
nre
of the foli
will cause a similBt' increase
1.1•
i
t
itinns below compens
t
leaf nrelJ
, Ie
on
ftreB index above compensation po
1
area index.
1
as
t
This would imp
leaf area
SiB achieves a maximum rate
t
AS
fur-
thi s nH'l.Jdmum value is ma,i
crop
in leaf area index.
area
occurs with increase in 1
value will be caused by
t
of
re
)
losses through
crease
saue.
b
i
loss
SBues (those below compensation
more
e
d
of the conse
f
the
ent fall
on coeffi
ent increase ,
arent photosyn
15
If however the extinction coef
t
increase in appa.:rent
cient decreases,
synthosl s may
phD
to remain constant or sligh
e in the
0100t) it might be
notion coef
constant, as
the partition of photosynth,ates to photo
nOII-pliotosynthe
(3
t11etl0 an.d
tiSS[fC
sing rate of leaf senescence equal
on, ceiling leaf area i
liC
the rn
of
n(~·w
would 11e re
me, the ceiling yield would then occur
of
crop
inereDse.
ted that new leaf production would
t
C~:UHH~
arml t photo
With a constant maximum rate of
(no
resul=
le;Jf
Wi
the mnou.nt
tosynthates translocated to non-photosynthetic tissues
eq'ual ::l
eld has never been achieved, while there is only
one
l~·t
nor
l)',_
q
t.""
nniJi-lg"
't./'.J.L.~
j..~
]ea~
~.
,,"1
qI'n~
l'~~aw
v~,
J.,r'L/.I(:'t'\.
Il __
(
dson and DortelO
1958) •
optimum leaf area indices were first demonstrated by
sugar beet, in
the 1 eaf area i.nclex was nl te:red l)y tht
leaf area index related to
this
and the remaining
consequent crop growth rate.
it was found that the optimum leaf area tnllex
for kale was 3.0 to 5.4,
The
ieh
tel' than 5.0 :I'or s
photosynthetic efficiency of these
beet.
16
(
the olJ
1
(1
)
eh 1
)
1
.
a white clove:r
t
of 5 5, new leaf
It:l~
0.5,
q
3.0 to 3.5
1
at
on I'ate, deereftS
1.
1
ill
( 19
) found. an
eaf
(19
1
on in
lef.l,f
l'J'Jnter.
on 1.n s
o:t
i
()11 ,
a tio:nships of
rate are necessary
ty.
c
relationship
subterranean
1.)tion 'Iud
enc:
(1961) a.cmons
ex on the level of
L
by
sol,eu.'
lation~
Ie
Cl
e (,)
ion. over a much
(1963)
lso:n
coe fiojent (K) i
1
rea
co
t
over
)
17
the lowest
aves just reach campana
They sng=
on
rn of new
ce K changes becanse
gest
Ie
1
en t
on
t.
(1
6), who
of leaves
ne of K is
of
s - red
on
on of
te clover
light
increase
causes :no
below
The consequen
s.
BSSO
011
to
from
over-
leaf area
5.5
9.0.
BeclUlse
workers have found
0
,
rate b
leaf area i
value of K
n constant or
decreas~~s
it
in crop
seem that. the
ally,
species o
lson and. Brit
of
tioD curves,
of Ie)
of K) ..
1964) resul ts s
e for
s swards.
a s
It is su
, successive new leaves
as growth.
cally 0.1
leaf area
s
(
,
occur
!
ential foli
s
high
se to a
st.ed that
more
K.
se to a cha.nging
s
s swards a similar
gher values of op
ly, few
on
th
18
ekseenko (I 959),
ue8$
Ie
Ie
, depending on species and. s
of
3
17 ..
on
of leaf area
e
subs
of
t de
se
is
t growth
i
on int.ensi
1957b) and clens!
cl 1951) were founll
es
es
to be de
BVlOunt of foliage.
of leaf area is so well as
ed
i
as of the genetic control of leaf size,
1
f
Aarance and tiller development
tempt to evaluate tbe usefulriess of R ec
on
(
iurnant of optimum leaf area
1 and Cooper 1961).
(3)
or internal factor a
c
of
is is undoubtedly the
1
Ii
(
t absorbell by
1
in nlla
tion of
oto-
1
s(mt
:'Ill
c hac
pro~
i,
i-
e to
1 a is
Ii
sorb
gilt
s
o
ferred to aBsa
rst
1 a
mol
astan]i
em
o
l:i.
o:f
d no reI
on
photo
t
e
that
1
eal
c) of the photosynthetic reae
on was 1
son (1948) stressed the
!Jane€! of
of s
1 concerl
0
Ii
1
(b
e
e
of
c
cess is I
f
the process ..
s s
recti
t absorl:>ing caps.ci ty of leave
tha
1
not
1 cOJ'lce:ntration/ulli t Ie
t.o
/n
t wei
i
was
1'18
i
area
thi s basis he found th
t.
tion a deoreasing level of Ii
1 COllcen
in
)
elsen (
reel to
leve a
m8~imum
to
c
on iM not, however, directly p
1 cancantre
oecuU e of
spa
on with increasing Ii
tical conditions
t
i
1
20
Oil
in
1948) , 1
s (
vari
cal 1
)
1
.
on
structure (Mi
t
er
ehl as a
tat-ion, 1fvhich is
i
on of 4:
sis, rea
an
orophyl
• •
2
Ie chlorophyll is
It is
ill nlOst :foliage leaves,
lJeing
co:ncel1
of
photo
o:f
)
1
the maximum
of
t.
1 sen
sen 19
end 1961; Gabri
IRen
po
on (
level of inactive abso
€I
i
In
liage will influence
e
of
on
t intensi ty falls
when I i
s or pas tUl'es where the
is
foli
it would be expe
nence
1
€I
Ii
t concH
p
ons ·helow
iIrt,
8
chlorophyll con.ce!!
tion
thetic rate of the
1. conoentration of leaves
s in the
to
on
011
been
t
of
lesser
chloro-
(1960, 1961), in stu
1 conoen
(200
a~
ons over a
0,,) anel tempera
that the rate of chI
si
s (1
)
C
1
es
nna
on
s
fferec1
21
:in successive 1 eaves.
Because a compnri son of chlorophyll
concentration in lea,ves of tl1<,) same f.l,ge would therefore
have reBul ted in a compari SOIl of leaves at eli fferent stages
of morphological and physiological development, leaves were
comp
:ott the :stage of maximum chlorophyll conteut
2
(mg./dm. ).
This sta[4eWaS found to coincide with the time
of maximum 1 eaf area, fresh and dry
showed. th8,t chlorophyll/elm.
2
ght.
Hi S resu I t8
was affected directly only lJY
temperature, which had a large metabolic effect, presumably
affecting the enzymatic steps in the formation of protochlorophyll.
This is supported by Virgin's (1961) results.
Indireotly, increased light intensity increased chloropbyll
ooncentration signifioantly through increased leaf thicI{nNlS I
wllile temperature had a tendenoy to decrease leaf thickness.
Chlorophyll eoncentrat.i on therefore appears to clepend on
light and
te~perature
interactions.
Younger (1959) found that under high light intensity
(7000 to 8000 foc.) and at low temperature (less than 1280
degree hours F.) the rate of chlorophyll degradation in
l)elllIlH~a
grass exceeded the rate of ch.Iorophyll synthesis,
thus cclusing chinrosi s.
SOJlIC
di sagreement flppears in the Ii teratllre on the
question of daily fluctuations in chlorophyll concentration.
(19tH) suggests that
ons are
rates of chlorophyll fo
chlorophyll
s
4
arts (1963)
s or
1
rv1onoco tyl edoneae was
vel'
low
Jrlon~
cotyledoneae it was
f f (1962) doubt
ons
occurrenoe of
conclude that the chI
s not fluctuate sl
ean leave
p
con
s
1
19(3) ~
of the fact that
€I
een dirac
resea
of
on
to
c
een
chlorophyll coneen
be
On
d increase
of
fi
•
, leaves appear to achieve
Ii.
d.
a leaves
as
1
me be
(1 9fH)
11ie
the chlorophyll can
ination to day 9,
t
fre
j.le
e
eaf increased rapidly to
sa (1960) showed that the to
Bot
t of some
wei
lorD
12 or 13.
Id
e legumes r:ulI.d gr:lsses <lecreas
en
23
defolip,tion..
There was a
lorophyll eon
e in
6.7 g/kg of dry 'WElight for I l rifolinm
of dry
t from
to 2. (3 g/lrg
ght for
sen
0:1' an t:n. tere st~l
the resul
erimellt on the chlorophyll concen
tiona (per leaf area
'per leaf weight,) hI successi "Ie leE'Yes o:f a wh(~.!;d;
an,t
oropbyll concentiona of total 1.caf, sh
weight and
Ie to c
yield he 'vas,
the relat.ive eontrihution of
cvln
{:')Rch pa.rt of the total pho tosyn tiw ti c sys
'fhor:nc (19
) found thHt the to tal appal'l:;:llt pho tosyn.=
enclosed stem of a barl
10
of
50';' of th[J.'t, of the
onately
tel'.
time of ear emer(~
IYIH~n,
'beclo'llJ,.t,e of internode elongation;
se~l
vege
onf~
VEl
ano
stage of
th.,
It woul(l
contribution of i
SE':em
or cereal s cute
1 e::l~r Fclhea th.s
th
ench leaf
fll"e
ill
the
enclos(:~d
ins1.l1e
under these eond:i. tl011!:1 tlw
ividnal l<".a:f sheaths to total
24
photo
(
is
(1950).
1
eOYl
wh:i.ch i
:i.
I
]1
on to
t
1 e f-j f
-tLr~ e fl
i
)
t
1
()f
0]1
h
o.
to 3. J
1
1
)
)
e.
()f
{lif
.
1
on of
mum
25
with leaf area i
bam suggests that
was significant (1'
= +0.815).
e poorer correlation was
Broug-
e to the
leaf area index failin.g to take accOlmt of the
tic aetivity of other parts of the plant or of
photosy:nthe~
enies
differences in chlorophyll contents.
&lother interesting result was that the ratio of
growth'rate to ohlorophyll i
which leaves were disposed ho
was higher for species in
zoutally or where flagging
occurred (olovers, leal e n:n.d mal ze) thaI1 for grass speetcs.
rrh:ls, he suggests, was clue either to the ohlorophyll of the
first group being more active or efficient in photosynthesis,
or to a greater proportion of the dry mat
produced accu-
mulating in the underground organs of the erect leaved
26
CHAPTER III
rrllis experiment was designed to measure the interaction of light intensity, crop growth
e, leaf area in-
dex Bnd chlorophyll content of two grasses, short-rotation
rycgrass (Lolium
grass (
x I •• multiflorum) and prairie
!illdenovii), after
IsDn (1963), under
pure sward conditions.
EXPERBfENTAIJ DESIGN
Randomized blocl'!: layouts were used for each of Urree
levels of light intensity.
In each block there were the
two grasses, five replications and six harvest occasions
(weelcly interval s) •
!Jlhi B involved sixty randomi zed plots
in each light intensity hlock.
Accordingly, sixty large
seed boxes (plots) were filled with sterilized soil, to
which steriliz{oHl humus and a complete fertilizer had 1) 113 e]1.!.
plAced close toga
1
that with
s
1
to o'h
nu-
supply wonld be
on
(H.I) seed was
B
on,
was from;
s s
of Butt's
1
8
s (a New ZealRnd cuI
)
0
ses 'tvere sown pure at
pI
1 t
deu
ties,
a surface area of 240
of 30
Se
s sward
seed/acre was deCided
l'ye-
accordance with farming
pI
fllean t
A
s
was placed 0.9 i
The same densi
ill a sowing rate of 200 I
ro
e
e
tlds rate is
•
j.
s that to
de
of
tiOll,
eld (Holliday 196011, 19
0
i
e
of 1900 plants/m
i
rrhese
10 be used.
t
e
ons
of
WRf)
ors.
2
19
a
".
)'5
t
"
s<t~t
out
unf1!:lT
na
'r.ho three levels of 1
ronmen
.,..'
II
of full d
hI
N~lico
1
e Ii
rna
t Ii
leach
ltght
,
c
t.
i
vely, were
s
dent
reg
t levels 09n only
e
:i.n
ce
IH~
e
th ohangi
lig;h t
cover preva:H:i.
e of
a
1'e
l3eW11
ad over the
of
to reduce
t of
1
Ii
1
od was
P
cember to early I·lebrUB
the 1.
t c
Ii
on
to
ly pI
0
1;1.011S I2t1'e
1)(3
p
reasonal)ly un j. :f 0 I'm •
s
was sown in late ])ecmllber, but lJeoause of
se
se
out
S
t
011
of
e
was
s i
e
BeeEi.u
s
over
over
1
comple
a
had to be
Ii
of bo
d
ses, covering the
e l:i
t
29
ity bl0
fore,
p
s, i.e.
b
It
two
SOlVll
ed on
II
orne
l~,t
harves
arne date.
e of
S
the grasses
sadvantage
t
of the grasses not
mental condi
de
under exao
same environ=
is disadvantage was leSR
ons.
that
light i
re
e
ve
bulki
Growth. was
on
64
pI
00.
from 12th
25
April.
ons for this
s tEl,}) 1 e,
ly
ad were
c
Clim
low
1 10th, 11th
levels of
1 (
of
Ie 1) •
dity
!nci
erature
• (oF)
12-18
II
19-25
II
2
2
1
1
?
, •.4
ra(lta~i
(0'7)
.\
(col/mn"" !day)
72.5
.0
44.9
43~8
61
74:
.. 1
4283
'1
.0
.,7
300
,.2
9
If
It
lV'
.1n.
•
'.;)
'J
&c~
92
378
367
2
was tal{eu
records while to
me
nco
s
ColI
sr radia
an Eppley pyrheliometer at
on was re-
s
terna-
art about 14 miles :from J,1nco
box or plot, consis
sfimple
at soil 1
o
ou
A
of
eovering an area of 2
.5
were el
perimeter
l'OW8
cut
is
sample ,'Vas
de
te.
were divi
samp
an
)
non-
( expa:nded
tiona.
(
to s
sen
A
ve Ig. s
leaf was removed for chlorophyll
leaves from 20 represen
I'
plan
were
i
l'
on of s
s
dual
wei
Wf'!i
were re
dry weight
A
twas
on value was used
Ie
es"
}'-
se leaves
t
of e
1
s) were
area against sample 1
1
1
an
ed after Jenkins (1959)0
en
sis.
Ilers (8
the measurement of lamina area
1e
areas from
dry
stem and
Hecords were
of
(~r
of
31
lIars, number o:f leavc8~
tillers/plaut, leave
1.
1 eavei::l/ti 11 ~~l·.
','vel"e
, stem, dead material
o
C
hours DIU1 wei
s
course
s were used
at
l'
the
per
t
ons, were es
the
C.. G.R.
e to
) per
ma
].
piallt dry
ghts
,
(1
t area of grmnul at
s
fj
'II
rate of increase of leaf and stem dry wei
80me basis.
on
) was
was
Leaf area
so
• representative 1 g3
o
Ie
Wflre
frOll}
each plot
BS
1 •
t of
f
or
entation
11
e8 :i.D duplinate or
to
P
] eaVEH:l
icate
hei
{m of leaves,
Ii
t condi
11
8
the required lNeight ..
rna
'I'ht s
ell were
la, were
through the
ODS
•
is
a
stems
1 contents of leaves
a
ly
a me
outii
and s
s
as
c b
plac
c
e
c
t
(1960) •
les for
1
1
darkness at
time was Hlways between 9 a.m.
a.m.
es were
be
ssihJe after
soon a.s
sed.
..."dIS,
, .
the
10.
1
am~
Since this experiment was comple
of storage of planttisf'lue samples i'or
me
s was found (Sestak 1959).
tiou
oedure involved the homog
Ie in 80% acetone.
1 g.
Iu
The solution was
to an
rst diced and then pI
zero
8
of
The
i
content of the Ie
to 88% and the stem tissue
ssue
8
to.
on could not be
e this
y
on, a mean fi
to
s, to ob
s
bo
ned
was
111 ace
mI. of
3.
the solution
diced tissue
80% ace
s.
up to about 10 mI.
sample was
Thi. s
100~
acetone was
found
waEI
of
zed for
of
BU
s
1
ant tissues.
fil
The samples Wel'A
as s
1 tel' over
a No. 56
• t.est-
d.
ng
is po
t, becanse
d have caused
absorhanee
10 mI. aliquot was
Cl11d
)
A 2-fold
density me
wi thin t.he op
nam
were
to a volum
be clear
For leaf tissne
1•
S
volume of 50 mI.
up
materi
densi
re
twas
'I'he extract
(
was
1]
on into an
to remove
1 pigments.
Btl
sue
Iter
B•
with
I'l1c~de
1
er I i
Filtration was
100
a fine
zero to 0.8.
8,
In
diluted
on might have been bt:1tter as
would have been more Burely
of
i ty
c
34
s
For
Iii
tissue a I-fold
were pI
on was used.
lu
in the lower
rt10n of
lution would
s
S
been
tome
les
a 10
81
t
10
1
.
to 0.3
rrl1e
0.3
e was
c
15
ad
• 1
aliquot,
&
conver
aoe
of
plus
neetone;
0.3
• of 80% acetone p
of
opthmm
fcrable.
Ie a control
re
All
s a s
t aliquot,
acetone •
samples were
1,
oxalic acid ill
• of
the 0.3
8eetone.
a and b
a
ace
The
1
011
to
b
i
g. 1.
sol
room tempe
am] plac
densities) were
Their ab
on a
ectrophotome tel' at wavel
cam
64:5, 655, ()
were re
G()6
fIl' U.,
S
f\
s of 536,
t thr'Jse
ation of to
red for
total
1 a
A
s
1,
b and
b
)
s
based on
of
(
1),
(1
)
Fig· 1 - Conversion of chlorophyll a and b to
pheophytin a and b respectively, by
addition of oxalic
acid
CH =CH 2
H3C
J===~----lI
CH
H3C
H
CH
H3C
H
2
HI
CH 2
II
°
I
H39C2002C
CH
2
H
HI
CH 2
II
°
I
C0 CH
2
3
C0 2 CH 3
H39C20 °2 C
Chloroph;tll a
Pheophytin
CH = CH
2
a
~
O=C
J==~_-ll
CH
CH
H3C
CH 2
H HI
cr 2
H39C2002C
OXALlC~
ACID
CH
H
II
II
°
Chlorophyll
H39C2002C
b
°
C0 2 CH 3
Pheophyti n b
Vernon meRBur
ComaI' and Zscheile (1942).
absorpi ti vi ti as'
the'
ecifie
(specl. ft e ab sorption. coeffi ci ants of
Q
ther
vmrkers) of chlorophyll anel phE'ophyttn over a wlde
of wavelengths.
Certain w8veleng,ths were thfm selected,
fnr reasons {"IVan in his
Itancona
wh:i"eh
:ng
1 a (mg. /1.
ChID
)
Chlorophyll b (mg.!:l.)
11"10
]
(d.A662 ) '.... 3.64, (IlA54-5) •• " ... e (1 )
:i:::
~5038
::::
30.38 (~A61,5 ) -+ 6.58 (~A662) •••••• (2)
chlorophyll (mg./l.) ~ 18.80 (.01\662) ~'" 34.02 (6A6
).(3)
= 20.65 ( AG66) - 6.02 ( A655) ••••••• (4)
""a\
(mg./l.) = 22.31 ( AS66) - 17.90 (
Pheovhytin n (mg./l.)
or Pheophytin a
. ~-) 0 }
0
€I
f.)
(~)
t)
Pheophytin b (mg./l.) = 32.74 ( A655) - 13.75 ( A666) •.•••• (6)
or )J>heophytln b (mg. /1.
filotal pheophytin
)
(mg./l.)
97.4,0 ( A536)
::;;:
~""'
or Total pheophytln (mg./l.)
whel'e
6.90 ( jH3t,6 )
= 79.50
~
=
2~1,.
60 ( AG6G) ••• (7)
26.72 ( A655) ••• (8)
( A536) - 0.29 ( A6(6)(9)
A666 reprt)sents the absorlHmee (optieflJ, densi ty) at.
66G mj'h AA662 r(~prel:3en ts t.he ehange :i n (';lhsorbHuee
Ii1.1"
l'1"t
662
etc.
rrhe control sample measures the ,amount of chlorophyll
a and h present, 1m t not the amount of pheophytin a
"1:1.
,According to Smi th and Bent t~'lZ (1955) it is not known whf'Jther
a
b occur
occur in chI
1
t
earanoe
i
lows for this in
ons (1), (2)
on
on
extraetion.
1
Venlon
s
0
is
1
of
the
ae"
(3) measure
1 lE}'vels
s of the differential op
b
re
converte{l s
1
COlI
e
of pheophytin on the alHlorbance ref1.CU
t.
con
ey
t
~~us
a true indication of
of
1
control extract is given.
ODS
(4) to (9), measure tbe
1
extraets.
e
chlorophyll levels pres
no
se
ant
occurs
to Vernon's
s are
1
tI
no eOl1version".
cause the
U1f
reading is
III
on
sorbance curve of the
so
wave}
of e
ft
steep
let 1
snOB values can be produced by a
Therefore Vernon used the
ons as eheck e
tions.
of
The choicc
e in
1
set
~e
5
nyu
rcplace
e
Tnf in
an ab
eophytill a
length
lower
l)ccause
s wave=
at
00
1) absorption i:n tllis
about
,
CCluati Q11S was
area was small.
se formu.lae gave chI
1
those obtained by
(
.:'
),
""
figures gave
while
oJ.'ophyli fi
not
s
b
used.
cc
could 'he
were not
c particnl
no
As
ded that Arnon'S (1949)
• /li
)
::::
12.7
2.69
Cb (
./li
)
:::
22.9
4.68
1 conc.
son
ne
to produce pure samples by Vernon's
i
(
would
re
cd and the laboratories
method, it was
To
s,
L
tioD coeffici
e
:fact
ons
be almost
s
the
a
s.
that thc
ever, only
model of
e-
(mg./li
IS
re8u1 ts.
. .. . •
.. . .
"
·
·• ·
)
flriment, for
s
ae,
s
·
S
(10)
(11)
• • (12)
of
corll~
30
All repli.cate da
were hulked and the mean value for
ta.
each harvest used t.o e.xamlne the time tre.nds of
mean valnBs thrOlJg;hont the growth p
best 'fit' was c
tren(l of these
atton. tn thfl t
eliminate the small.
culated.
'110
ssion of
od, a
Initiol computation with linear
End quadratic regrestnons, showed thnt the devi ii.ol1s from
i fi can t and th erc~
the qua.dra tl c :rcgre s siems were no t s i
fore gave a sRtisfacto
however, has the
inJtialJy
I
f:i
tv.
quadra
sadvnntages of givi
negativf~
values
ever inoreasing values wi
tberefore deeided to use an fJrl(U tional
Rion 80
c regression
that the two diRadvantages of
te:ll'Ul
8
i.n
rn
ere
s=
e regression
might he overcome.
A cubic regression, whtle 01
i.n;od:ing the eompnlflion
of Hnidirectionnl c.b.ange urith t
, still has the disadvnn-
tage of giving negative values
tinIly.
decided
th,~~,t
c) 1.
It was therefore
saion (Pearl-Reed curve) would
1
where the value of y (dry wei
t, leaf area index or chlo-
)
Y'O
o
t
rve
c (i
en
f
of
1
Increa~
1
ch
1
11
I
1:' 1
ai
1
l-:1re:nt
H.nee v
on
'1'0
be
(}llS
f
Ii
1
1
i
t If
v
:I
41
the following headings:(1) Hry weight yields of
sand
three levels of incident light intensity.
af area indices of ryegrasB Hnd
H.nder three 18vc11') of' ineident light
(3) Chlorophyll indices oJ:
grass under
~lree
l'yil"lgl'aSS
rie grass
int(~nsj
tyo
and prairie
levels of inoident light
intm'lsi ty.
(4) Inter-relationships of crop growth rate, leaf area
, chlorophyll index aDd level of iDol.dent
ligh t in tensi. ty.
(1) DRY VlEIGIIT YIEIJDS OF ltYir;GRAS~::i ANT) PRAIHIE GHASS UNDEH
fl1HHEE l,EVEIJS OF' INCIDENT LIGE'll IN'l'1i:NSI
The mean leaf, stem and (:lead uHlterial dry weights (D.Vi.)
42
of
prairie
s
x harvest
at
usion of dead
)
s o·f
e 1
are
oco~sions,
oro
(
rPB.
Ie
of
il
(;~
t
ot
0
t
dod an
cl
1
0
f
s
c
f
res
Fig. 2 ..
CUl~V(~S
it was anticipated that
p
on on
elds of
ses,
thes(~
nellc
e
wou~.
g./m 2
yields recorded by
hi
S
.)
(8
s (7040 11:16./ao.), 1:0 only 64
e
:normal autumn Ii
81'
izes the
of
on of
c
i
011
1;
e of an ade
811ts
nu
on b
(
ric grass reeo
th
d
t.
7
ight) to 337
lOO~~
0c'
:1'
o. be
e total dry wei
(
e
0
the sward.
tIl time, are r
1.
t,
."
dry wetght
to
of
at
:!IS
co
of
1.
e
when
on causfHI a
t
eld of bo
j-
OilS.
s
grasses~
t was
to
43
TalJle 2.
'>
Dry weight yield.s (g./m."") 01' ryegrass and
rie
grass at three levels of radiation and at six
harvest occasions.
nyeg:nlSS
29
43
50
57
64
Leaf
101.8
142.2
226.1
323.0
347.8
472.4
Stem
29.8
49.9
92.9
147.9
1
,0
216.3
2.3
10.6
27.5
30.4
52.8
498.4,
533.2
+
-58.6
741.5
+
-61.1
dayLi.ght Dead
Material
Total
131.6
194.4
329.6
S. fi!.
i"
.....,13.0
-21.1
7.3
+
-20.0
90.6
124.0
221.0
271.2
::148.0
~l81.6
24.4
40.3
87.0
114.5
165.0
173.5
10.0
13.4
25.6
48.8
Stem
clayli
36
+
Dead
Mrl,terial
S.R.
115.0
-+
-13.0
16(3.7
+
~17.1
318.0
+
-24.6
398.90 538.6
±'68.4 .:t63.0
Leaf
57. 'I
63.1
133.0
136.5
239.6
231.2
stem
16.0
17.6
42.3
46.2
88.8
88.6
0.3
2.7
6.4
11.2
17.3
81.0
178.0
189.1
339.6
337.1
~Potal
dayUght Dead
Material
73.7
2,1
..
44
(
29
)
.36
43
~
J~G
liB.7
97.3
0.9
3,.7
15.
•
.1
189.0
-+ 9.2
:t19 . 5
6.6
83.6
118.7
189,1
2::1.5
.5
81.4
i
0.3
S.EIt
.9
46.0
't(~rn
Total
.4-
237e8
']10
@
.7
139.4
i
";'7)
.1
104.1
162. ;5
107.1
-+ 6.3
":"15.8
58.0
99.1
14.9
31
-
.~ ,
~~
9
8
~~73f3
"
<)
(,J
• :3
191
~l
.1
12(;.
1
6.2
~~89.
.8
21.1
1
.7
3I.
.6
.6
7
7
,1" 7'
159.8
.1
22n.l
60.8
94.2
101.8
1 9.1
0.8
2,B
8.8
.8
221.4
.8
301.1
(~Q
er
tal
S.E.
.9
.0
o
<)
CcJ
130.3
193
4.0
.
.3
.,
~
Fig. 2 -
Total dry weight -time curves of
H1 Ryegrass and Butt's prairie
grass at three levels of light intensity.
800
_700
-
N.
E
en
-500
~
I
(!) 500
W
.....- - - . Ryegrass 100 0/0 daYlight
0 - - 0 Ryegrass
50 0;0 daylight
lIlI----i(1( Ryegrass
30 0/0 daylight
-- - - - .. Prairie grass 100 %
0- - - --0 Prairie grass
50
II- - - - -f( Prairie grass
30 %
%
daylight
daYlight
daylight
~
>~
o
400
...J
«
300
~
o
~
200
100
o
o
10
20
30
Time
40
(days)
50
50
70
(rrahle 3).
EXHl'l1ination of the indtv1dual cOlllponcnts o:f to-
tal dry we:i.ght show tlHlt stem and leaf dry
welght[~
were
decreased in a simil,'lI' marmer to total dry weight.
1'lH:>'re
were, however, indications that with a 50~ reduction in
daylight, leaf dry wei.ght was redueed more than stem d.ry
weight.
This WBS e
ecially true for prairie graBs.
Also,
30~ ryegrass stem dry
when daylight was recluced to 50~
weight was reduced more than that of prairie grass.
These
observations are supported by an increasing leaf dry weight
stem dry weight ratio 01' ryegrass,
th decreasing (laylight,
prairie gra.ss this ratio dam'eases slightly (rrable
while
4).
Examination of the dead rnaterj.al component of total
dry weight showed. that 'INhen daylight was reduced. by 50%,
there was no·signi:ficant change in the amount of dead materiHl accumulated in the sward, but when the daylight was
:furthf3r decreased, the amonnt accumull"!.ted was highly si
ficantly
E.educe~l;.
gn:i.~
Addi tionally, ryegrass accumulated
flignificantly more dead m<:l.terial. than did pr:Hrl.e grass under
<:tl1 light 00
tions (Table 5)0
This suggests, that <:lIter
a similar period of growth, more light reached the base of
the sward at 30% daylight than at l001i, daylight (and tIl
rie g:rass compa:red to ryegrass) or t.hat inereafwfl cll"y weight
production caused reduction in the level of
avail~)le
~o11
47
rate of seneSCCJJce of leaves
S CHU
s.
o.i
ance of
s of
1
ta1 2 D.
(g ·/m. )
v
v 30%
(
1 D 67
28.26
11.
s.
+++
v 30~~
(
< 0.001
tl.
~
0.87
4. 4
.68 +++
-
0.23 n. •
0.13 n. s.
n.s.
0.27 n.s.
1.59 n. s.
0.73 :n.s.
0.85
1.83
n.s. :P> 0.05
gIltl stfHtl dry weight
e
• •
n.s.
0.33 n. s.
v 50'~
2.
o of
n. •
...
s
ss at day 64.
100% dayli
s
e
t
2.
2.1
1.85
-
48
Tahle 5.
material dry weight
linnlysi s of variance of
64.
Elt
Dead Material (go/m. 2 )
lti gh t ~ 100tJ,j v 50%
n. s.
( 1 001f.~:.5 O~) v 30%
13.54:
Variety
5.14
+
IJ X V ~ lOO~~ v 50~~
3.21
2
SO\Vll
ividual pI
a
the influence of level of incident
(l
s.
nos.
at common den::.!
} plants survived, examination of the
s of to
oj>
rI.
(lOO%+50~) v ~O%
Heeause 1111 plots were
++
os ano. all
revoals
on on the compo-
dry weight on a per plant and per unit area
I ground lJ[1si s.
The t:r(c;nds 0:::' tiller and leaf pumlHn:' pn.l.' phmt, wtth
By (hl.y 6 1, reduct
'
had caused high
gni Ii cant
in dayli
tions in the number of
ti 11 ers and 1 ea.ves/plant and. hence till aI'S r:md leaves/uni t
Fig. 3-Leaves/plant, tillers/plant and
leaves/tiller of H1 Ryegrass and
Butt's prairie grass at three
levels of light intensity-
I-
Z
«
...J
7
a..
6
l /)
5
Ct:
W
...J
...J
I-
4
-..-- -.-- _e-- -.--
3
2
-
_0
10
24
~
20
«
...J 16
_.
a..
- 12
l/)
W
~
B
...J
4
W
. - - -0-
0
Ct:
5
...J
...J
,I_
4
W
l/)
2
w
1
~
!...J
_x- -
"
--0- --0- --0
--K
10
.,,-..,;
:1.- -
___ ~L- -
/- '-::0;;--
Time
-~-
_e--- ._It- -
-0- -
~--~
3
W
_ _0 -
)1-0-
-.- .-=-ot-)lr --)(- --x_e-:---
-
-0_ -
-K
-0
..,.,... .........
~
(days)
o~----~------~----~------~----~------~----~
o
10
30
20
40
50
• Ryegrass '100°'° daylight
Ryegrass
50·,. daylight
I( Ryegrass
30·,. daylight
0---0
II
....
- .. Prairie
Prairie
It----001( Prairie
0----0
grass 100°,. daylight
grass
50°,. daylight
grass
30°,. daylight
60
70
50
11
of variance of
v
(
+++
v
1
l~< O~
lHl"
G.16
",.
3
:n
€.
i'<O.O)
]
3~t
'~'"
t1
(
1
i)
tj
O.
t
n.
1'<0.
c1,!'(~lJ
e~;\.n
,
..
•
1~
f:I.
>0.,
y more
11
e
)
dayli
eantly
e
• •
SJ.
Whpll
t
t.el:'
ant ( an d /ul~'l t; r're
II
t
;i::f
~
c
, )
f:""
of
,,~
0.
decrease
1
c
11
t
j
-'-
L,
of
wei.
11
-i.; •
of
it
<,
,~
ally
8,
F'ig~
4
£1J:1(l
ft
fies
rccllt
tIl t
in
n decrease in
lant) ,
11
11 e!' r.lwllbe
:irj e
Ie
er (2. 4: to 1. 5
11
on :I.n
SiS
11
8m
)
1
11 ex'
(.8
el'
lIar
Ie 6,
of a
t
t:lon,
:1.
ons
i
to
P
.1' ~>
ts
s
ly
on in pTairi.e
1
on ifl tiller
1
1 flU t) ,
ilst the reduction
on in mean
t is
e
ller
t.
.,"-'
01" RYEGRASS
GHT
mean 1
s
1
OfH"
leaI' area i
e
cos of
glVNl
TallIe 7.
time, are represen
harvest
s of
tted'
Fig·4-Graphical representation of influence- of
light level on per plant dry weight
composition at day 64 .
,.....
100 %
daylight
30 %
OJ
-
E
200-
Rye
Prairie
Rye
Prairie
Rye
dayliqnt.
""
. I
Prairie
~
Leaf
I
<D
-
W
1 50
f-
~
>a::
o
a::
W
-.J
-.J
~
z
<{
W
2
~
Stem
100f-
50
I
~~~EF
;::
?~~
•• Iii
7·8
2·4
5·5
Tillers per plant and
1 ·5
4·9
1 ·2
per ground area·
Dead Material
58
.
'llable 7.
tees of ryegrasB and p
MeaD leaf area
rie
grass at three levels of light intensity.
(
)
29
36
4.3
50
3.59
5.64
• 60
8.57
9.81
.:to. 67
• 41
±1.30
:tl .
10.65
11.~J6
15.55
16.M;
0!.0.4,5
5.63
±0.59
.89
±1.82
.67
+1.29
2.68
2.93
6.54
6.~n
12.03
11~41
.33
;:t,0.51
.84
+0.89
±,O.78
+l.~W
·4:.17
5.59
9.74
14.05
16.14
daylight
±.O.26
:to. 54
10.39
-l,0.55
.17
±,o.66
±1.74
50'b
daylight
4.42
.,.0.50
6.52
9.91
13.44
12.92
16.70
.63
+1.38
+0.85
+2. <1:2
,,,,1.16
3.05
5.61
+0.45
9.09
10.80
12.11
13.60
±.le23
+0.50
+1.14
+2.47
Ffl I f,/i .l!:
dHyli
t
"....,
e 'l)
3.77
50~
daylight
30,h
d;:Wli.ght
Prairie
10o~b
l'
30~)
daylight
L.)
57
l~?'.
G4
4"0
18.26
glCt),SS
+0.19
logi stie rf::lgressions in Pig. 5.
Examination of Fig. 5, i11-
dicates that except for ryegrasB at
30~
area i
that a 50~ decrease in
ex values ore very similar;
daylight, the leaf
Fig.5-Leaf area index-time curves of
H1 Ryegrass and Butt's prairie
grass at three levels of light Intensity.·
18
15
.
14
0
><
W
Q
)I
12
!
0/0 daylight
.. Ryegrass 100
J
o Ryegrass
50 0/0 daylight
30°/0 daylight
~ Ryegrass
e- - - -...
0-----0
Z
)f-----I(
Prairie gr,,\ss 100 0/0
Prairie grass 50 0/0
Prairie grass 30 0/0
daylight
daylight
10
«
W
0::
«
IJ...
8
«
W
....J
6
4
2
o~~~~--~----~--~L-
o
20
40
Time
__-L____~__~
(days)
50
60
70
i
'It eau es
e
ly :co
dayl:tght hiM3
area
1
ater values of 1
ly
ex"
Ie-af area i
lOO%
.26 (
of
1
11.
t,
(,
Ie
caus
a small
in
ria
reaction
~as
e
s it
not s1
of
1
arlee (
rm in
s of
1 e 8).
00
0.11
v
n.s.
67
fig Se
I,
V
,
10O~'{;
(
v 50%
v 30~
n. s.
o.
Jl* Sill
0
JJ.
P" o.m;
s.
at
56
F'urther reducti.on in· the radtat1.on level catuH:Hl a significant
reduction in the leaf area :imh:1x of })oth
ses.
As l(~.!'lf area index is dep")lnden t upon. the nurnb(~r and the
size of i
leaves :it t8 of interest to as!HlSS U\O
ividu
influence of reduction of incident radiation, upon these
conrpOJJents.
cant
HHdll.ction of daylight to 501~ cl:lused
redu~tion
8
sig:nin.~
in the number of leaves of both species, as
a resBIt of the signiftcant reduction ill tiller mnnlJor
(Table 6).
This large rednction in total Ie
set slightly by a small increase in ryegras8 individual leaf
Br\~a
and nn11l fi eel eomple tely lJY a large
jn(~rea!H:Ol
in prairie
ight
frable
.9..
Mean tndivid.ual leaf are,a (em. 2 )
1 @:O~~ dayl:i. gh t
Ryegnlss
Prai
e grass
further 1'edu ced,
7.0
t~le
;;'!,t,
F)O~
r.l.~
.,7]~ell·t
I~
""
. ' ... 1::;,1
•
wa~
day 64.
30~
(1"Vll'"~lt
,"
.1 <0", • . ~~L ,
<
5.3
3.7
12.7
12.4
further reduction in Tyegrass 1 eaf are.?
index was due to a l.arge red.uction in individual leaf area
whilst the reduction in pra.irte grass leaf area index was
hy decrease in leaf
nmnl:H~r.
57
INDICES OF
OF H1GIDENT l,H:IIT
,
mean 1
I
stem' (
1 (C.I.) yields of
oro
of inci
j;J
w
are
s
s
Graphical
Ie 11.
the
time, are repres
1
1.
c
by the
I
li'lg. 6.
011.8
S
01:'0-
m 7.3
1 index values
(
2
ight) to 3.9 g./m. (
s at
i
)
1
t).
Of
(4.8) re
torest was the
for ryegrass at 30~1 dayli
it's
e for total (try
d
Ie
e
level of
ction in
cause a similar reduction
for bo
grasses,
30% (Tal) 1 e 10).
i
It
a
ions.
1 i
1 cont
nrc s
s
gher chlorophyll
Examination of the
ex shows that total leaf
il
com~
stem
ly reduced with decreases
Fig·"6-Chlorophyll index time
curves of H 1 Ryegrass and
Butt's prairie grass at three
levels of light intensity .
........
-
N.
E
OJ
......,.
7
X
W
0
Z
«
w
c:::
•
o
• Ryegrass 100°/0 daylight
0 Ryegrass
50°/0 daylight
It Ryegrass
30°10 daylight
6
II
5
- - - - ..... Prairie grass 100°/0 daylight
Prairif' grass 50°10 daylight
*" - - -x Prairie grass 30°10 daylight
0- - - - 0
«
...J
...J
>a..
4
I
ocr::
9
I
U
3
2
10
20
30
Time
40
(days)
50
60
70
59
ehlorophyll, s
of 1
o:f
day 64.
1 :i.
1
chloro.
(
v
o.
2.41
n. s.
8.63
+·t·
3.76
n.s.
2.
s.
1.
1:1.
n.s ..
Chloro.
:1
ex
2.36
.
8.9
10.
3.12 n.s.
•
n • • P>O.05
i
on.
ruduc
1:1
1
1.
of ttu! to
as
[1
1 tndex (
of enl
perc
Btem chI
1 con
1. ,
1 contEmt,
1 stanl
y
1 f:) ""
'"
1 percer>
:1,
dry
1
1 percen
tirllc
•
:n. •
11.S.
_m___
' ______________________
. _ ._ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _• _ _ _ _ _ _ _ _ _ _ _•__ _
• __
. _ ._ _ _ _ _ __ _
a
•
generally decreRsit
60
chlorophyll, stem chlorophyll and total
ehlorophyll (C.l.) (g./m. 2 ) of I'yegr.lss a1'H1
praIrIe grPRs at three levels of radiation
and six harvest occasions.
)
100%,
daylight
50~~
dayli,ght
29
~HJ
43
50
57
64
Leaf
L(H'i
1.85
:>,.72
3.53
<'1. 70
7.00
Ster.n
0.13
0,13
0.13
0.21
0.18
0.29
1. 79
"1·0.27
'1.98
+0.32
+0.30
3.74
4:,88
+0.89
7 • ~>,g
+1.06
Leaf
1. 47
2.19
3.15
~{.
48
0.68
[5. 62
St!".m
0.08
0.15
0.19
0.19
0.26
0.30
1. 55
+0.40
+0.46
+0.21
-.",0.53
3.67
5.94
+0.04"
5.92
+0.28
Leaf
0.93
1.16
~L02
2.00
':t.67
4.62
St(~ln
0.07
0.07
0.13
0.11
0.24
0.21
1.00
+0.13
1. 23
.1/·0.22
2.15
+0.30
2.11
+0.50
4.91
+0.39
·~,0.84
Lflaf
1. 35
1. 53
3.17
~.51
4:. Ll2
5.76
Stem
0.10
0.11
O,~W
0.16
0.27
0.42
1.45
+0.10
1.64
+0.15
.:to. 36
3&37
2.73
+0.28
.:to.tn
'L60
6.18
+0.56
Leaf
1.28
1. 77
2.62
<L35
3.89
4:.
Stein
0.08
0.14
0.16
0.27
0.25
0.30
1. 91
32
+0.56
.<1. 62
49
4.14
+0.89
4.68
+0.38
'ratEd
III 0
tal
2.34
2.85
~,O.
36
3.34,
--.--,~,,~
30'~
daylight
IJrairi e
100%
dayligbt
-
'['0 tal
,gI'clSS
11'0 tal
.
50%
da.yl ight
30~0
dAylight
4.83
'l.lotal
1. 36
+0.08
,~·O.
2.78
~.O.
~l8
Le
0,94
1. 69
2.74
3,,:38
3.48
::l.64
em
Total
0.05
0.10
0.19
0.19
0.23
o
0.99
+O,n5
1.79
±O.07
2.93
01-0.41
3.57
+0. ~2D
3.71
:::0.38
$
~~::l
3.87
+0.66
61
p
1 as
on s
1
(days)
of ehlo-
st oc
ions.
29
;:!5
43
ight
7.3
5.3
4,. 7
50,:; daylight
5.6
5.2
G.G
5.8
.1
dayli
G.G
5.3
6.1
5.3
~~9
1007~ d
~O,~
(days)
157
64~
3.7
3.9
4.
ti"
5,,1
4.8
4.4
36
57
64
5.7
6.B
6.1
G.3
2
G &~)
1000,1
' JI,>j dEryl:i
t
6.7
6.6
d
i.
t
6.2
7.1
5.8
.9
30,~ (1
],
t
5.0
5.6
6.6
5.4
:enl 'lively
t;
ill.
eo
is
v
to trtl s
phyl1.
(j"
1
1
01'0-
10
-rely H
o:n? t
11),'1'1
t
j
e stem chI
low
1
Ii
i
i
1
c
,
tiorls at the
ed
0
tll
ohl O]to~~
62
1 i
ex is placed, would suggest
tern
very little to to
O(ftI
)
ennee
mest probably u
leF\f (Jompol1 en t.
serVH
Wllile
l~Ot
t
a 1
o:n
lizes ass
1
su
1 comes i'rom the un om
no measu
leaf
of Ie
Vfore
on/volume of
1 conce.Iltr::l
s ,
0--
ssue cannot be
elson's (1948)
of
l/uni t. 1e11f area, waf; used as
Ii
acity of leaves (
whEn'\? only
ave-
orophyll cOllcentrfltion Cl:Hl Ill'l col
1
e.
b
aXHmjIl
sa .had a
on
i
In addition, the
s
1 concentrations and light :l.
of
11
a
wh(~
S,
concen
of
e 13).
incH vi (tlHll pI
s
m
on of
a
t
as 1.11
13 it would lJppeBJt>
ly censtant 1
1'0
tal
Oll
t
chI
1.
at
Ie ryegrass ehlorephyll COllcen
each
en.!:;
ConcentrRtion of leaf
leaf) of
se
on
levels of incident
oeCH
1
ons.
29
30
4.64
3.28
j
t
3.89
~3.
88
2,,96
3.
3.
3.
i
t
3.46
3.97
3.09
3.22
3.
4.04
ere
tiaIly
i
eel
Oll,
t
e
p;reator
s
64; (
tiOD in leaf chI
1
1 ), it
causes
that a 50~ reduction in Ii
or
ons
1
light
s of' variance
s
2 .
of
1 (
].
's (1960, 1961) results.
aD
64
Analysis of variance of leaf chlorophyll
centl'fltion (mg./dm.
2
eOl1~
of leaf) at clay 6/L
chloro.
Light
100% v 50%
8.05
17.42
L x V
100';0 v
50~i]
(!OOf~50%) v 30%
::~
++
+++
2.94
n.R.
4.10
n.s.
P>
----------------------------------------~--.----D. S.
0,05
is achieved hecausG of the la.rgc decreflse in p:n:tirie grass
chlorophyll concentration.
light intemd ty,
With a greater reduction
rie grass chlorophyll concen
tioD is
little affected, while ryegrass chlorophyll concentration
is
nearly sf gni fi ean tly
lnCl'fH':1 fled.
ni:fieantly higher chlorophyll corwen
grass at each light inteD
(4:) INrrEH.-HELA
so, ryegrass bad sigtiona than did prni
ty.
ON~mIPS Ol~
All data in this section <::u'e
from the calculated
e
65
logi
.,
c
s
¢
TIl e in
u
ce
ed
1 eve 1
f
0
ous sec
t rnO:iation on
f
rate o:f
croil
ically
7.
0'
o·
(3
10
F'i ,-,f:! • 2,
at
i
old,
(
1
11
(
t
ce 1-
i
1
1)
1
1
vtllues) of
J
t
(Iayli
1
(g. 1m. ''''),
t)
)
)
m
.
flY)
1
i
77
t
90
i
.66
i
t.
t
t
15.6
G4
(
.0
91
,17
1-1.4
12.2
)
520
17.
10.
1
'llimc of C •
.00
06.
5.7
1
·
·
17
•9
·
42
· •9
[50
Fig· 7-Crop growth rate of H1 Ryegrass
and Butt's prairie grass at three
levels of light intensity20
18
--en
W
\
\
12
~
0::
o0::
\
o
0::
\
\
\
\
y..
e
(!)
a..
\
----\
10
I
t-,
~
o
o
E>
U
\
\
\
\
\
\
y..
4
Ryegrass 100 0 /0 daylight
0----....0 Ryegrass
50 0/0 daylight
MM----«K Ryegrass
30 0 /0 daylight
e---_e
2
.... -
-
-0
Prairie grass 100 %
daylight
50 0//0 daylight
Prairie grass 30 i/o daylight
0----0 Prairie grass
,.... -
-
-II
o~----~----~------~----~------~----~
o
10
20
30
Time
40
(days)
50
____
60
~
70
67
Ie 15 it is
Sf'{~n
}
that
c
o
Ii
i
i
t
l{ls
1
0:1'
i
the
e
hH;l
mum?
H1
on of the rel ntio:n
P enlCS
em.'
eel
of
e
that
1
11 • •
ra
e
ce
s
1
t
011
1
a1
area is placed
lar 1
i
m
ent of leaves, so
on
t.
ction :i.:n
ra
j
with decrease
df:lyllght, is
e
Fig- 8 -Relationship of crop growth rate to
leaf are9 index for H 1 Ryegrass and
Butt's prairie grass at three levels
of light intensity·
20
-E
-
18
~
ro
u
---
16
N.
3>14
W
~
0:::
12
I
I-
3:
10
\
0
0:::
(!)
a..
\
o
\
8
0
\
\.\
\
\
0:::
U
6
4
_---e.
0>---0
)(
2
II
Ryegrass
Ryegrass
Ryegrass
100'/ .. daylight
50·/. daylight
30 0 / . daylight
.. - - - .... Prairie grass 100 0/0 daylight
o-----<>Prairie grass 50"/0 daylight
It-----I(Prairie grass
30"/0 daylight
LEAF AREA
INDEX
\
\
\
\
69
,
to a re(lnction t.u leaf ehlorophyll eonc
compensation point.
growth rate at a much lower VR-
achieved it's I!H.lXl.nrum
lue of leaf area index.
ination of
1~e
to chlorophyll index (
relationship of crop
B a similar relation-
g.9)?
ship as shown to leaf area Lndex axe
to daylie;bt to 50~~ cBusHHl
phyll i
ex
1'1
x'ate
t thvt a reduction
r('lCluction j:n opttmmll chloro-
values~
From f1.'able 15, the time at whioOh maximum crop growth
rate was acbieved was used to
chlorophyll i.nrlex vallles, lyhteh are given in
index
Table Hi.
fPIH3 rasul ts ohtainEHl hy Brougham (1960) for
~lort-1'otation
ryegrasB with full davlight were a Maximum
nrop growth rate of 18. 9 g,
area
in~ex
<)
/111.
"/d ay. at
Hll
optimum I
of 6.5 and chlorophyll index of 2.5.
suIts were obtained
th a mean total solar
These 1'eigtion
2
elouclless clays of G80 cal./em. /day, \vhie11. is twice
level encountered in this expe1'iment9
N:l:f
Or!
tlH~
As is suggested in
the diseussion sectton, the a.pparent doubled. efficiency
of EHlergy conversi o:n in tIli s experill1.ent compa:nHJ wi th
Fig. 9 -
Relationship of crop growth rate to
chlorophyll index for H1 Ryegrass
and Butt's prairie grass at three
levels of light intensity.
20
18
>.
-E
ro
.
"C 16
-
(\I.
--...... -.....
"."..-
/
/
~14
"-
"-
"-
"-
'.
W
I-:
«
12
0::.
I
I-:
~ 10
\
o0::
(!)
\
a..
8
U
6
o0::
\
'"\
\
\
\
\
I
\
)(
4
•
• Ryegrass 100·/. daylight
Ryegrass 50·,. daylight
I( Ryegrass
30·,. daylight
0----0
)!
2
... -
-
-
-<II
0----.<)
)j,-----f(
Prairie grass 100·,. daylight
Prairie grass 50·/. daylight
Prairie grass 30·/. daylight
4
CHLOROPHYLL
AREA
5
INDEX
6
7
(g'/m~)
8
71
Brougham's results is due'to the superior
timum Ie
area inrlex Rnd chlorophyll index values obtained in this
experiment.
Table 16,
From Table 16, the leaf chlorophyll concen-
Maximum crop growth rate, optimum leaf area
index and
orophyll
opti~lm
jnd(~x
at three
light intensities.
c.o.It'max.
(g./m. 2 /day)
L.A.I.opt.
c.I.opt.
(g./m,2)
Hyegrflss
100,~ daylight
20.5fj
11.35
4-.42
daylight
17.72
11. 35
3.80
30% da.yltght
10.58
10.11
4.00
I}:rtdrie grasfi
100~[, daylight
15.66
11.90
3.70
501~. daylight
1·L47
11.50
3.47
30'1;' daylight
12.22
8.43
2.70
50~t
tration at maximum orop
(rl'ahle 17).
gro~th
rate oan be oalculated
'rhos"" rel'mlts i.ndioat(-:) tlu'I.t ryegrass had
greater ohlorophyll conoentration (mg./dm.
rie grass at each level of
that
110)08
')
Q
if!
of leaf) than
cident radintion, and
of these values oauu"! within Gal)rielsen't~: (19tj:8)
optimum concentration
of 4 to 5
mg./om. 2 ,
at which
72
lJ~ahle 17.
Leaf chlorophyll cOl1cel1t!'atio:n (mg./dm.
2
of leaf)
flt maximum crop growth rate.
Prairie
incident ra
3.20
3,1]
atioll is most efficiently used.
nation of Tables IG rnHl J7 tt woulO appeal'
From. o.n
the decrease
crop
III
levE'l of incident radlat.iou
in the two grassAS.
th rate
'VU.f~
caused dLr
tifllly
Ignoring the erroneous result
deorease in ryegrass growtb rnte
was rlue solely to the decrease iE Ie
)
():F 1
the growth rate of prai
ehlo
.
1 eo:neen-
to I've
e grass c
~
-
tl
caused by the smaller decrease in leaf ohlorophyll.
ss \vas
eOIn,ee~l=
·tI·~I+i'):r1 (~lry
20f le~f) of -l~~(~
'rR~rie.
a~~RQ
A,-be /ell-n'
I.., ....
}_
.
!,_!V_,~IL_,
r.f&
a smellIer Ilecreuse
_."'_,,{{~.~
:U-'
._"
.J.._ .. .JI_
t:::,<",C~,:.:D~"
optimml:! chlorophyll tndes of pl'
th lYwderE\te f:lw.de.
0
th he
iug (30~ daylight) the large decrease in prairie
area
prenlude~
any compensatbry effect of the Rlight in-
Ol'fHWe ill leaf ehlorophyll cO.ncentratio:n (mg./dm.::l of lea:f:)
73
til
('flll
re
t;
tlH:) to:)
WAS
~lrther
1
decreas
{lry
mattor
1
ODS.
s
on of the correIa
on
te
cates that the m
achi
is 9i
(1'
Bes under three 11
related to optimum
can
.9(6)(1'<0.01) bui. llot to op
(r
)
.
t
des
the
(~
c
of a
j
s is
prairie
i
s jn
caloula
relialdli ty
r.IO
on the result for ryegras
he plae
it is:i.
mum ohl
tom and hence
InO
t,
7
DI
y
J
to
of inel(1
o
(
1 (C.L),
()
to
t
the
11
e
75
this
eriment, total
pel' uni t gI'cmnd area was
ot
as the me
UfH~d
e
enee
of tneident I'a(Uation on the
s 1940; Mitchell 1953;
tha t the
8 rIO 0
sion
tn
of net carbon assimilation, beari
of
nerement
t
~
ot
we
19
19
t
)
1
e
t
(19
) and
's (1963)
area
which
le~)f
but; does
t
of
J'll te
not altogether con
:rem that
will
op
creases with the level of incident
1
on.
ge differences in m
1960;
son of
of
1)
0
growth ni,te
1118ms 19(3).
ack 1963; Loomis and
se value8,however,provi
vo
f
s no
ciency of dry matter produc
ause
s.
Snme maximum crop
are 51 g./m,
11 i mn s 19 G3), 32 g. /m .
cd f;rass
s (
ted
by rn
A
assess~
on
76
')
1959b), 20 g./m."/day for Bnnnpda graEJS (fJllotC(J by Loomis
?
l1.tams 19fi3), 19.§J;./m.'/(lny for ~~;hort~ro
trnd
tion rye~
2
grass (Brougham 1958h, 1960) mUl 17 g./m. /clay fo:r peren-
Brougham (1960) are
lar to those obtained
er full c1
g. I IT!. <:;'1rl.ay for
,">
l:i
ii tn this
1'0
tion ryngril.sfl Hnd 16 g./Il!. {/(IHY for
')
That these values were nbta
ed
irie
tt.l Ip.ss
hvl:f of
th(~
B
8urpri
ng and most
ohIo
larger
in this
lim
r
As t'ov:nd
pIn
0
da
Jd 1961; nl~ck 1963), roOue
oJ
s to be
in
lOYAl
of :1.
on
It was Avi-
re~uoed.
dent however thnt tye
l~Hl1;
si v~o
t{)
eltffn.ges
(1erJ.t raOltl tto:n
to proFl
n.t
ir rela
1 (I
dayli
t.
ve
UIlcler fnl1 iiflylJ
JIering ':1hD.ity o:f th!") rye
,ass
grass, more th[tH eompoHIH;l.tOtl for
tlle
with p
3'S
rie
lcasAr tiller
77
s
11
110r
that
levels of 1
dent
on
1:.l
over
etio:n
ter mean
liecanse o:f' i
t.
J1
i
1
se
is
t
Bul t
:tn
ons 01881
of
man:n!H'.
lar to
pasture establishment.
lishm
e of
Idis
our
1
As a
11
on
on of
ose
:in
neighbour cans
~i
s erect
to its
plants to RssumB an erect
rm was further accentu
a
on,
1
:in prat
e
ot'
1mv lovels of
s
lifi
t,h
78
more ereot plae
of
and reduo
,iJVB
a (TallIe
ers of 1.11.113:1:'8 arlO leaves per
6)
s
ons
abI
deereasl.
t
been more
f
occurred was
~
on
t
i
accumul t
l:ldcti
i
t
cans
on,
ller
E) 31.'
growth habit of
accumulate much less d
8
8,
under each level of
ously a complicat
monti
1
ation of
eli
s
of
1
m
1
1
cial
11
Ii
f
£110
t of
vely
sil)l e
hi
IS
0
leaf area
chlorophyll
ty
l1io11 plants/
th the
growth from
mum
11 j
1
nrl1ch
because
t
lower
]i
ons
79
or
nor
mature asso
s ere a
IIi
a
er of:
me
axp
have be
pl.n:n t (]
Ii
ons
by
_. L" ,
for
8
), were 11.4 and 11.0
1958b, 19
( 191:::6
11f1
ecttvely.
011
laTger than
1'18 I!1U
r sll
(1960)
(n.o)
1
(
,19
(1958b)
al
r
011
ryegrass (7 1)
s ob
1:;1f
)
t
t"
1
:n
ere
of
(6.
s
tiOIl
ss (7.1), p
f
were
ons whieh had heen
OI'
S13
It is
1
ftlOSt
s
habi t oJ' growth,
se
even
i
density, the
1
volume
plBnt
lli
i
ow],
ss
(:0)18 tHY,
on
ge
eqlH~J
e1'
r(f
e
14")
o
ocmli~
t
80
1 OOl~
/'"~
of
gras
"
-
,
t, the
and prairie grass
fJ),'Cll
tn thts
t
01'1111
had little influenoe on
hrrt
8
fn~
er
re~nu
on
"'.
Xl
aroa indices uf both sn otCR.
form of
t e
coef
t
i
an
oiants to be ]es8 under reduc
1t
t
1
thUl:J
o t
l'oJ U
flnSl)]p
leuf bros index to level of i
o:f 0 p t
oj
,Jltl ('1961)
·where plant lC'laf
t e.t-,te thn.t
1s
on
ehIo:1'o
Be
ow
mum ehlo
Ie
a:re[t i:n
vtJ,()Y'e
tr~ (1 el{
"by
l.l(~~ne
the
d
1
i
c
gr"tJ':fr~=,
more oJ (I ,"€.':.
tIl
t
~."r
Rl
1
t
o
1
1
Ie
(
chI
dex (
]
]
I;"
]
t
de
n.B
.,
hi.
1 eEt,~f
!~,
ttl"O~)
on d ee:f"ea Fj
onC(';II
1 :i
t
H
CHUB
1
~")"l1
'llhi ~3
th
1
]
COJJSO
en
t
"
rate
t
1
1
0:1:'
:fUIlC
g
t
S
1 coneen
chI
Ie
is
(
f
f
)
1
1 )
)
to tb
that
e
t
JJ~
:1
l'
lJOS
,s
flWSt
lJe
B,
o lyt ['1 11 (') ('t..
s undcT
(1960) ree
o
1
conse
enee
The
t1
culat
1
was
u
com-
82
o:n
1'0
ss of 2.49,
e ol,toi.nerl
va
e m
Ie
1
(0)
7.:1
Wt' S
orophyll l:ndex
,
3.
0
o.
Tf'st.
It seems
t
011S
(
mum
the
at
os
n 'will be
t
(j
the
1
ons
1
poi
s
ove
11 be
t1:81' feW
en.t
and distribution of leaves
hn
will
i
1)0
tnfln
e level of
try
o
's (1960)reslJ.lts snpport
1
on of his
1
0
show
8,i:l
conc{'~ntrE1.
OlO.S
gUJCf!S
1
1
s,
cu-
the c]overs
tha:n
chlorophyll concen
of leaf) of some clovers
S8tH!
(
1
18 ),
on (
ses
(
growth rate calcul
conc.
clover
on
s
4.16
3.84:
3.
)
.
83
se of
hut b
7.;o:n
It
(~
nueh
d :not
t
]_,f.-)I~ge
lifHlf
a:r
ilS
cl
were
OIl'S
(
0
)
1
totol stem
love.r s
;3.1
the
11 had
~,~es
,
tlfl
i
red clover
p
t u:nder the smne levels e
r8
are no 1
tiOrl
f:fermwes be
on of
rel
s
so that
,
.in
t
en
r
milates be
)
t of
80S
()
1 eo:ncon
ti Olt
c;r-l.nnot lIe
efl
as b
s
Sill
OJ'
st
lr~
clov"nt'
9
1
leaf
orophyl1 cone
elover, the gre
e COl]
1
of
84
the to
1
in
enoy of
etlsurHd
clover.
the
I
8
erop
of
:i
1 ].•
..
cd)
({
e
v(';
i
on of
.
'j'
Incl
.
the
on
51 whtl
100, 86
s of
1
),
i
() :f
i
on
.,d
f
on
is
j
o:f
o~~
<;,
~d
t, aD.
fllAle
so
not
40.
It is
t from 1 O()?~ to
i
the
olIall
ot
m
66 :for
f 100, 88
on In
se
a~
men
on of lOOt
Ii
C
it
o:n
1'e
eElr
that
1
i
Ii
Ii
s
tJ
dcly
ly
t
Oltl
85
01J
,re effi i
of rel
o
pro
is of
e reIn
i
j
ve eb
tion.•
t Ta
os decrease, BS
l'fites of
J
)1
10
;
t
tinn
f
8
{I
uud
ton (1
\ - , D,., I
1 '19"";1\
s
t
e
~Hl1ni
e
he 'the res
i
not u
i
on of the effiei
t
increment per
ti
t
los
on
of
t
1 per
~ej
or e
(
t wei
• W.
t of chI
2
1
it
t
t
1
4.1
86
e grass at low levels of
of
(H:tnfH~
011.
iation :i.n
of tht'l much lower levf:!l of indde:nt
s expfl
e:nt eomp
(1960)
valtH~9
in
of 4.
.23 g.
ric graB
for
lower
7.77
on
~ffi
e level of in
s are more
th a 1
even
I
dent radiation a
1.
If once
ag~in
weight, the inereaa
si
Ii
ton 19
19
cause
1... 1.
th deerensi
ts
(1960) findings,
t
sen.
levels of
roo
in the to
root/shoot
t
(
1
) wonld
of e
10
11 cap
R
ju t as efficiently as at hi
of produ
inc Teasi
is eonsi
results
ction
Ie
ons
growth rf:lto (
iation.
otion,
ri.e
1
th the 1
1.
dent ro
duct:i on for
cney of
g./go/tn.
al
th
the
eid
aney of
o
1 1954;
resul ts a:nd
t
c
on to decrease
s1 ty.
, support
indica
i
Brou.ghmn's
matter produc
on
87
i
(1
CI"Op
P elr -ft(l
enl
t
expo
1
() }1
..' ~
"'}\.
t1l1 1 01 t f'}
to th e 1 11 C' ,
t
0 .it"
.'
'JJ
0
Y'r~
C1 I!,
.~
{iti (~11
.
88
VI
1
, Ie
88Cl
1
Ilea D,t six
C{~S,
1'01'
at
e last harvest occasion (64 d
redue
Ii
t
OIlS
tn
leave
no
dent radiation to
rt:'C!ducecl the nmnber of
si
per plant
1
e in
\
I ,
per md t ground. area
eeies interaction was
1 al1 t,
B
1)0
B~parent
f:lwards hac1 Sl,
in
while deereRsB
cau
11
ss tiller
more
1-
1 (-:)ve1
HthUtion, oXlullina
1
ar of
f:i.can
e grass swards at
1
leave
ller
on oi'
iJ]
1
t
Ii
e
t
s
89
w
th
P
81
i
t
than
1
c
t
t
es
nei
t e
1
t
.f1.
e
etiun o:f
to he a resvl
1'e
]
t oJ'
oj
t11 the some
s,
for
Ie plnnt
:r'at(~
It
:l.s
parts, leaf
elilon)c-
tosyn i,he
l'
bo
t ench lovel of 1nc1
on (1'
eant corr'el
h
= +0.966)
be
lenves con.
ens
1:1
1
1 cmJC
1
tion, as me
1
<'Hll
1 01' i:oc1.d
(1960).
It 1. s
WOHI
th
if root
been
i
Ie
i
e is
~ecreaBeB
inclu~ed
oant correlation
W89
in i
in to
i
91
ACKN OfH 1 1WG EMIi:N TS
I
H.D'I
debted to Professor R.H.M.
oonstru(J
h(Jon
t the inves
m
ts also m
s
s
me
gatton.
o
rl for treatment of d
sticel advice and
• G.
o
80
e
to
0
, to
on
• H.
sou
s who so ge:mn'ou
ental
1
I
s
am
so
to
:fe's
evera:nco.
CiS
02
, L.
• 1959.
o
of
p
lants i
)
of
.19.(
• 1
6.
luo}
.
e
)
{)
Pol
24:1
19
influence of
J
on
i
t
i!~tell=
.
.
1(}61. (In)
Gnee 0
11
t'Don
the
o
• Bo t" ,
Be:p(1 jet,
1i
t.
.1\11. 19
,,3$1 28: 42
3.
of some
. 102:582-589.
lJU
on of
on
the ligi.lt m:i.eroel
1 ea.J ClTo;ert
In
"',
'"
.
Ofl
]3]
13]
(wk
, ~r,]\I.
iol0
'
es j n
tIl
,An ,:11
1:'1
0
ronme:nt
mIt
l'
OJI
ffecent
llJack,J.N. 1959b.
I
e role of
i~nn.
Rot,
~te
li~ht
fae
J oal
~:iol
r in]
itl
1
,1\,
• 195f). Physiologio,}l
e analysis of
m
in
Hul
;'(
{~
I
eolo~
t
r~ II (1
:i. s of tl.le e
f'e(~ts
t
on the
tttl~e
(~ 1"
set~,S
owth
~],ant
onl:ll
0
l'
[I.
t1 orl
94
ta
.,
.,
VB
19:
1
101
1
os in the
en
tan
Is
ronment
1
0
:1'01' JH
its Ecolog:ieal
tml 1
J
G.L.
• !
., N • • 15:
TIl
lson,G.I,.19fJlh.
G • If: •
c
1
the
anal
t
is of the Differenti
on
8i
vo Growth UatB of
t. ,
.
..
t
Se
:N. S. 15: 37 3~
i
t
,G. A. 19 6.
Ii
0
1
i
of
of
G. 1960.
130
some forage 1
pi
r .
c. 14:575-594 (
)
rho
s
• 795.
1
nlrrnt
J,
Hot.
:31
conte~tB
of some native and
95
1955. A study l.n rate of
Brongham,
H.
Brou.{~ham,
pasturE~
1956. Effect of intensity of
growth.
J:'oli::l.ttnll on
regrowth of lHlstnrc. l\.USt ••J. l\.grie. Res. 7: 377-387.
Brougham, H.
1958a. Leaf development
clover (Trifolium
707
s. 1:
18.
Brougham, P,.
1958b.
terception of light by the foIl
of pure and mixed stflnds of peu'lture plants.
l~ust.
~r.
Ag r i e • H,c-') s. 9: 39 - 52 •
Brougham, H."W. 1960. rrhe relatto:nshtp
lH~tlyeen
the critical
leaf area, total chlorophyll eOHt(·mt, and m
rat(~
of some pasture and erop plents. Ann.
mum g:nmth
t.
?
.,
N.S. 24:463-74.
CepikoVR, A.H. 1963. The chlorophyll oontent of timothy
pl~nts
of different ages. Dull. Moscow Soc. Naturalists,
BioI. Div. 48:131~133.
(In) Herb. Abstr. 196.1L 34:No.196.
ComaI', C.L. ana Zscheilc, F.P. 1942. Analysis of plElut
extracts for chlorophylis
~ectrophotome
8
and b by a photoelectric
10 method. Plant.Physiol. 17:198-209.
Cooper, J.P. and Edwards, K.J.R. 1959. Selection for leAf
area
ryef::rass. Hep.
Ish Pl. Breed. Stu. p.71-75.
Davidson, J.L. and Donald, C.M. 1958. The growth of swards
96
clover
oJ'
flrea.
1
to
p
st. •J.
2.
lip ,J .It • 19
• L.
CII
logy and
1
(
ESeO
P
crocl
..
'" )
:,..')
1
errs"
It
pI
51. Competition
.1.
Ian
c corupeti tion.
st. .J.
c.
c. Res. 2:355-376.
t
1961. Competition for I i
tl.
01.
p
13.
tu
19
asture
. Ahstr.
1
:1-6 .
1
e t
f
1.
e ra
pI
1
f
1
1956,
t
of cll.1
1
a:nt
1
eon
tL C. 1961.
is wheat
1
. 11.
0
eJmeSB •
131
1 of ohIo
• F.. 19
1 con
Ii
ts
t:lklt
14: 28=:~9
0
101'0
t
siol •
.
1:5~
C:au
ant
Chl
the
1 clevel
Of the wheat
pl[!:nt vt
to1.
~
otosynthesis to Ii
Mu
(:lld eondi :I.o:n8.
IIi
,n.D. 1962.
1 v, 1,1
R. 1960b.
on :iu
tosy:nth~~sj
t s
:l.lldividual COX'll
attun and
old.
a:ntp
P1;~rt
R. IH60e.
r-flow plan
ster
J.
II.
[It:i.on and crop
.Tonkins, H ....". 19
H:r'f:'8
fmt
t. Crop Sci. 3:]07-1]0.
Hol1tday, H. 19GO,i').
rrolli~ay,
J.
g.
6:
n
of
.1.
itl wh
measnrt
s:!.ol.
of de
ssion of'
lA~ves!
pln.nt comm
r,oomts, H.S.
the
and its meant
es. J
lliams,
vity : an estimate.
tion of matter in
• J. Bot. 14:304-324.
A.
19fj3. f",Taximum crop pro ductt~,
98
n.
Macl;:l:rmey,
so
so
1941,
tion of light by chloropbyll
tiong, J. Dinlog. Chern. 140:315-322.
Mi t c he 11, K. ,J. 1953 a •
fluenne of Light and. fI'emper<1
s (Lolium spp.). L
on
Pattern of
Vegetative Dnvelopment.
uenee of light and
tchell, K.J. 1953b.
eX'Bture on
the growth of ryng;ra.ss (,--....;;..;.;.....;... spp.). II. rl1he control of
lateral bud development.
:fluenco of ligbt
Mitchell, K.J. 195
of rye
rat e
0
s
:f t 1. s su e :f 0 :no
Mi.tchell, K...J. 1954,1).
nnd s11.01't-ro
crB.
I'llHl
(l,olj.1Ul1 sP-p.).
III.
ora. Physlo1. PltlI"t "'{:
spo
o:r
ion rycgrass. N.Z.J.
1'0
OIl
tern and
51~
es. L
i. Tech. 36A. 19
tal
06.
tcbell, K.J. 1955a. Growth of pasture species. II. Pereonial
tion ryegrass. N.Z.J.
sho
i. Tech. 37A.l-
Ml tc1H311, K. J. 1955b. Growth of pas ture spec! es. II. Pererrni nl
ryegrass (Lolium -per(:~nne), Cocksfoot (Dactyli.s glor(H~rata)
I1IH'l.Paspalarn (_...;;;...0;""""__
.J • 1....
fl.::-1tlUtl
)
c··
7. 1
•N
• _'d,')Ol.
h
Lec.
,)0 7'A:
n
8-26.
Mitchell, K.J.
~er,
D.M. 1958. The light regime wi
pastures. N.Z.J. Agric. Res. 1:61-68.
Mitchell, K.,J. .aIle!. Coles,
tion anrl
sha~ing
~.Lrrl"l.
1955. The effect of defolia-
on the growth of short TO
N.Z.J.Sci. Tpch. 36A. 586-603.
t100 rye
'"
t..:::l 0
99
11, K.J. and HI
C. 19
t.il
of pastures. N.Z.J. Agric. Res. 1:
Hoper, K. 1958.
11, .!',.J.
Ii
1.
5.
ffwt
on
t
lopm
the l€H:l.ves of
0:(
N.
,tl. Agric. lle • 1:1-1 •
, 'r.
1
Is
s,
on
eetrnm.
1
0)1
Ii
s
t
s,
('rts , D.
s, H"J.
over
energy on leaf
m.o:nooo tyl
Olifij
ow
.i~
0
tiller
H.K.,
AS
, N. and
t.
scue. ,J.
19G:-3. Ou chlorn
in pI all, 1; ml
R. V.
1
• tl.
1
.,
•
f1.so
S
In
(1
dicotyl
~!8rtill)
t
ee of
:221 226.
jf',
1.
von
.J. P. 1961. The Jullu
thy .fmc! m
1
101.
. 1
(0)1',
()
1
]00
It,
i
ttOll
reflection
.
cht s
of leave ,
ee
ehl
last
Amer.
t• 3
•J ~
errol
10
s
.,
TIle
. • 19
tal
ps 11
en
synthe
f]
,
f
63 •
(1 of
i~1.t
o~r
BinI. PI all t (
G. 19610
il1i , n.M.
s
1
C
s :i:n
tlH~
ts of
chI m'opllyll
leaves.
t.
, ,LIT.C. ::md
:12 91
S
III
1i
+.
"
6.
grmv
9
of
p
19
1
~1ethods
in 1955.
of
on roots of
39:f391~900.
1955. "Mo
Be
4.
7
1:
p
tnre,
f
.,
li
t
101
H("}ilon
of
1
over
of
lJ
1
t
1
.(
194:9.
••
\
I
p.
II
o
f
()
1,0 om].); •
0iSI)rl
flto
i
Bot. ,
1 C
on
1
102
L.
,
c
HHiO.
1
I
1 ti
:n
32:11
• 19
:form
On
*
ion of
J i
01
1
2.
'"I
1 sm:l ..L
ea
1
t
J.
19(:0.
01
f
1
10
*
hropw
s
~
romne:n
f
i ti
01
v
l
c.
IS"
i.l.ati
e
hetween sp des
Jeaf
e
t, ,
.j
N.
<OJ
11:
6.
physiol0
. 4:
••Y.1956.
f
1:1.1
ID1~1
growth :In.
",II
;.--.!
.
(
\
~l
o.
versity of Not
1t110
s of
CEll IH1.f:1
; fill
on
rrh i
r~:l
1
.
fi~ftS
.)
1,
1.
103
• Do t.
on Ie
WI?!tson., D ••T.
9
French, S.A.W. 1962.
t
•
to
l~ppl.
i.XlCn'l<:lSO
Blol.
50:1i-]0.
of
cuI t.i
ckliff, J.L. and Aronoff, S. 19
•
of d
n.ti on of el1}o1'o
leaves of
cnn.
W:lLlltams, H. D.
Evi~enca
j 010
~17;
for Bbscence
590-;:>94·.
1963. On the physiologic
Rot.
.,
I
N.S., 26:129-136.
l1iams, R.D. 19648.
sl
Uli 1
peren:ntal gra.sses. -'tun. Bot. ,
nCG
tion
].11
N.S. 3S:-119-42{i.
},OHC1.,
p
lliams, R.D. 1964b. Translocation
Outlook on Agric. 4:136-142.
lson, D. 1963. Genetical studies on
rh~
grass. M.
Thesis, Lincoln College, N.Z.
, V.H. 1959. Growth. of
n~3
hernmda
or vari.oHs
ligbt inten51ties. Agron .
•J.
51:ti57~559.
c
1
[nICEl
1>:[,)<)
1
ki
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11
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1
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=
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8
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flt.! o:n.B wore
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