Time of sowing and wheat yield in northern New South Wales

Abstract

The influence of variation in time of sowing on grain yield in five wheat cultivars has been studied in the North West Slopes of New South Wales over the period 1967 to 1971. Highest grain yields were obtained when wheat was sown at the end of June so as to flower at the end of the first week in October. Reductions in relative grain yield of 5 to 7 per cent were recorded for each week that sowing was delayed after the end of June, or 9 to 13.5 per cent for each week that flowering was delayed after the first week in October. Lower grain yields from late sown crops were associated with lower leaf area duration after flowering which could account for 69 per cent of the variation in grain yield. Lower grain yields in early sown crops were associated with lower ear numbers which could be ascribed in part to the influence of frosts.