POTENTIAL FOR INCREASING EARLY VIGOR AND TOTAL BIOMASS IN SPRING WHEAT .1. IDENTIFICATION OF GENETIC IMPROVEMENTS

Increased early vigour and vegetative biomass at anthesis should lead to yield improvements in wheat. Fifteen introductions were compared with five standard cultivars in Western Australia at Wongan Hills in 1988, and Wongan Hills, Merredin and Esperance in 1989 to identify useful parents for their early vigour and biomass production. Two times of sowing were included at Wongan Hills in 1989. Dry matter production was measured at all sites except Esperance at the early vegetative stage (49 to 55 days after sowing), late vegetative stage (56 to 75 days after sowing), and at anthesis. Some introductions were more vigorous in the vegetative stages, and produced more biomass at anthesis than the standard cultivars. Experiments under irrigated, non-stress conditions showed these lines produced leaves and tillers more quickly than the standard cultivars. The full growth potential of these lines may not have been expressed fully due to environmental limitations. While variation for dry matter production existed within the standard cultivars, it was not adequate or consistent enough to be of value in breeding. Dry matter production at the vegetative and anthesis stages was correlated significantly with grain yield in 1989, but not in 1988. Broad sense heritabilities for dry matter production at the three stages were generally high, averaging 72, 73 and 69% for early vegetative, late vegetative and anthesis dry matter production respectively. The importance of assessing the value of early vigour and biomass in breeding populations is discussed.