An analysis of a wheat yield depression caused by high sowing rate with reference to the pattern of grain set within the ear

Abstract

Grain set in spikelets of ears was reduced in spring-sown wheat established at high sowing rate (500 viable seeds/m²) compared with wheat planted at normal rates (250 seeds/m²), the reduction being greatest in spikelets positioned near the base and near the apex of the ear. Regression analysis revealed a significant and positive relationship between final grain set and spikelet dry weight at the early boot stage. Poor grain set in wheat grown at supra-optimal seeding rates was attributed to a combination of reduced carbohydrate supply and water stress in the young developing ear.