Differences among wheat cultivars in their optimum sowing times in Western Australian environments

Document Type

Conference Proceeding

Publication Date


Conference Title

Australian Society of Agronomy 13th Annual Conference 2006: Groundbreaking Stuff

Place of Publication

Perth, WA


Wheat; time of sowing; sowing window; optimum sowing time; rainfed


Agricultural Science | Agronomy and Crop Sciences


Cultivar performance in wheat varies with time of sowing, which is contingent on the time of seasonal break in rainfed agriculture. We conducted more than 25 field experiments with 2-3 times of sowing after the break of the season over three years at sites spread throughout the agricultural belt of Western Australia. An analysis of variance model with a Genotype x Environment x Management (time of sowing) structure and a sowing ‘window’ (using smoothing splines) approach was used to analyse the grain yield data. Cultivars differed for optimum sowing windows and penalties for early sowing (ESP) or late sowing (LSP). In 2005, the LSP was generally greater than ESP and that the decline spectrum for cultivars was wider with late sowings. We conclude that (i) sowing wheat at the first available opportunity may not always be the best economically; rather cultivars need to be matched to sowing time according to their time of flowering and maturity; (ii) cultivars in the low ESP group are either long season cultivars or have sufficient plasticity in their yield components, in contrast to high ESP cultivars which have a medium to short life cycle coupled with low plasticity for yield components; (iii) most common cultivars in WA have a relatively wide sowing window; (iv) cultivar options available to growers outside the most common time of break of season in WA, especially early sowing, are limited; and (v) growers should keep sufficient quantity of seed of a range of cultivars to cover all likely sowing times.