Journal of the Department of Agriculture, Western Australia, Series 4


W K. Anderson


Wheat, Oats, Sowing date, Yields

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When crop variety and soeing dae are matched so that flowering occurs in the 'window' for a particular site, grain yields are increased and yield response to inputs such as nitrogen fertilizer and seeding rate is magnified.

This response occurs because the srop's potential for setting and filling grains is much improved by sowing at the optimum time. However varieties differ in their yield potential because they have different lenghts of growing season, which probably affects grain numbers, and because they have different inherent grain sizes. These differences affect the way varieties react to sowing date. Figure 1 shows how the yield rankings for the wheat varieties Aroona, Gamenya and Gutha grown in Western Australia's central wheatbelt can change with late sowing.