Bd. Thomson et Khm. Siddique, GRAIN LEGUME SPECIES IN LOW RAINFALL MEDITERRANEAN-TYPE ENVIRONMENTS .2. CANOPY DEVELOPMENT, RADIATION INTERCEPTION, AND DRY-MATTER PRODUCTION, Field crops research, 54(2-3), 1997, pp. 189-199
The adaptation of a wide range of grain legume species (Lupinus albus
L. cv. Kiev mutant, L. angustifolius L. cv. Yorrel, L. atlanticus L. a
ccs. P22924 and P22927, L. pilosus Murr. acc. P23030, Cicer arietinum
L. acc. T1587, Lens culinaris Med. acc. ILL6002 and cv. Digger, Vicia
faba L. cv. Fiord, V. narbonensis L. acc. ACT60104, Lathyrus cicera L.
acc. 495, L. ochrus (L.) DC acc. 537, L. sativus L. acc. 453, P. sati
vum L. cv. Dundale, V. benghalensis L. cv. Early purple, and V. sativa
L. cv. Languedoc) to low-rainfall Mediterranean-type environments of
southwestern Australia was examined in relation to canopy development,
radiation interception, and dry-matter production. Species were grown
at one location, and in two consecutive growing seasons (1993 and 199
4). Dry-matter production was large for most species, particularly in
1993 (maximum biomass > 580 g/m(2) for all species except L. pilosus)
which had above-average rainfall. V. faba and P. sativum developed gre
ater maximum biomass than other species, and this was associated with
high crop growth rates (CGR) during the early part of the growing seas
on and large maximum CGR. Other species which produced large maximum b
iomass (V. narbonensis and L. ochrus in 1993) developed dry matter mor
e slowly during the early stages of plant growth, but achieved maximum
CGR similar to those obtained for V. faba and P. sativum. CGR of thes
e species increased rapidly close to flowering as air temperatures beg
an to rise. Species which produced large maximum biomass intercepted a
greater amount of photosynthetically active radiation (PAR) (r=0.73
and 0.70* in 1993 and 1994, respectively). There were differences amo
ng species in the efficiency with which intercepted PAR was converted
into biomass (radiation-use efficiency), but these differences did not
closely reflect differences in dry-matter production. Cumulative inte
rcepted PAR was positively correlated with the fraction of incident PA
R intercepted by species (r=0.87* and 0.96** in 1993 and 1994, respec
tively), but was poorly correlated with cumulative incident PAR. Diffe
rences among species in intercepted PAR were therefore not related to
differences in the length of time species were intercepting incident P
AR (a function of crop phenology). Greater fraction of incident PAR in
tercepted by species was closely related to green (photosynthetic) are
a duration (GAD)(r=0.60 and 0.78* in 1993 and 1994, respectively), bu
t was poorly correlated with the efficiency with which green area inte
rcepted PAR (described by the extinction coefficient). Maximum biomass
of species was also closely related to GAD (r=0.78* and 0.84** in 19
93 and 1994, respectively). These results indicate that in low-rainfal
l Mediterranean-type environments, grain legume species should be sele
cted for the development of large green area index (GAI), which should
maximise the interception of PAR, production of dry matter, and conse
quently seed yield of the crop. (C) 1997 Elsevier Science B.V.