Effect of waterlogging on the grain yield response of wheat to sowing date in south-western Victoria

Abstract

Two experiments were conducted in 1983 and 1984 in the Hamilton district in south-western Victoria, which examined, in 1983, the interaction of cultivars of different maturity with sowing date and, in 1984, the interaction of soil waterlogging with anthesis date. In the first experiment the grain yield of Isis and Condor were not significantly (P = 0.05) affected when sowing was delayed from 18 April to 13 May despite greater DM yield at anthesis of the April sown crops (44% with Isis and 8 1 % with Condor). Early sowing resulted in early flowering and in Condor 25% fewer grains per ear. When the effect of anthesis date on grain yield was examined in 1984 at a poorly drained site (Hamilton) and a nearby better drained site (Tabor), it was found that early flowering caused yield reductions of 46 and 25%, respectively. The reduced yield at Hamilton was caused by fewer grains per ear and a lower kernel weight. Grain yield was found to be associated with the severity of waterlogging during the 30 days before anthesis. For each 1% decline in the mean air-filled porosity of the surface soil at this time, yield was reduced by 0.29 t/ha (r2 = 0.83; P< 0.05). When the soils became waterlogged, nitrogen concentrations in the plant tops declined to low levels between stem elongation and anthesis. The need to avoid waterlogging damage during stem elongation in spring may necessitate anthesis being delayed beyond the time currently recommended for the district.