AN INVESTIGATION OF THE GRAIN-YIELD ADAPTATION OF ADVANCED CIMMYT WHEAT LINES TO WATER-STRESS ENVIRONMENTS IN QUEENSLAND .1. CROP PHYSIOLOGICAL ANALYSIS
M. Cooper et al., AN INVESTIGATION OF THE GRAIN-YIELD ADAPTATION OF ADVANCED CIMMYT WHEAT LINES TO WATER-STRESS ENVIRONMENTS IN QUEENSLAND .1. CROP PHYSIOLOGICAL ANALYSIS, Australian Journal of Agricultural Research, 45(5), 1994, pp. 965-984
Wheat improvement in Australia has made extensive use of germplasm dev
eloped by the International Maize and Wheat Improvement Center (CIMMYT
). The opportunity for further yield improvement in Queensland was inv
estigated by comparing CIMMYT lines and Queensland cultivars in irriga
ted and dryland environments at three locations. CIMMYT lines were ide
ntified, with greater than 20% yield advantage in individual environme
nts and between 15 and 20% yield advantage over the six environments.
The line mean repeatability for yield was moderate (0.492), with the v
ariance component for line by environment (L x E) interaction 4.2 time
s that for lines. Therefore, while the CIMMYT lines expressed consider
able L x E interaction, there was scope for further yield improvement.
The water stress differential between the irrigated and dryland envir
onments at the three locations strongly influenced L x E interaction f
or grain yield. Pre-anthesis water stress generated more L x E interac
tion for grain yield than post-anthesis stress. At the two locations w
here pre-anthesis water stress was severe in the dryland environment,
there was no association (P > 0.05) between yield under irrigated and
dryland conditions. However, at the location where there was little pr
e-anthesis stress and a degree of post-anthesis stress there was a str
ong association (P < 0.01) between yield under irrigated and dryland c
onditions. Grain yield was positively associated with the yield compon
ent grain number per unit area in all environments. Grain weight showe
d little L x E interaction across environments and the majority of L x
E interaction for grain yield resulted from L x E interaction associa
ted with grain number per unit area. Grain number per unit area was po
sitively associated with the component grains per fertile tiller but n
ot tiller number per unit area. Grains per fertile tiller was in turn
positively associated with total dry matter at anthesis; however, ther
e was no direct association between total dry matter at anthesis and g
rain number per unit area. There was a weak association between days t
o anthesis and grain yield in four of the six environments.