Flowering times of wheats in south-western Australia: a modelling approach

Abstract

The time of flowering is important for the yield of wheat crops in south-western Australia, where the risk of frost damage and the onset of drought can occur in the same month. Relationships to predict the time from sowing to flowering were derived by linear regression of duration on mean temperature and photoperiod for 11 cultivars. The models were tested against independent observations of flowering measured in time-of-sowing experiments conducted at five locations over three years. The model accounted for 71-95% of the variation in the independent observations of duration from sowing to flowering. The slopes of the regressions of observed versus predicted values were always less than 1.0, significantly so for four cultivars (P<0.01). The mean deviation of the predicted from the observed varied from 2 to 10 days, depending on the cultivar, site and year. The model was used to examine the effects of seasonal variation, sowing time and location on the flowering times of early, mid-season and semi-winter cultivars in south-western Australia. Predictions over sites, sowing dates and years demonstrated that widely differing developmental patterns may be required to exploit the range of environments and sowing dates in the Western Australian wheatbelt. The durations from sowing to flowering for mid-season and semi-winter cultivars were less affected by the variation in temperature than cultivars with rapid development patterns, and the variation in flowering times between cultivars was smaller at cool locations than at warm sites. The use of the model for farmers and breeders is indicated.