Effect of sowing date and N fertilisation on grain yield and photosynthetic rates in maize (Zea maysL.)

Abstract

Introduction Photosynthesis is the ultimate physiological limitation to crop production. The photosynthetic rate depends on leaf age, genotype, assimilate demands by sinks, and the effects of environment and crop management. Leaf photosynthetic rates decline with age after full leaf expansion. Under non-stressed conditions irradiance is the most important environmental factor causing variations in the photosynthetic rate. Higher transpiration efficiency (the ratio between net photosynthetic rate and transpiration rate) was associated with higher water-use efficiency in several crop species. Genotypes of a species might be expected to differ to a small degree in photosynthetic rate, but in most environments the greatest scope for improvement in photosynthesis will be agronomic. The photosynthetic rate per unit leaf area routinely increased when mineral nutrition or water availability was improved (Edmeades and Daynard 1979). In earlier studies the authors examined the effect of sowing date on the dynamics of the growth and growth parameters of maize grain yield. The present research was carried out to investigate the effect of sowing date and N fertilisation on the grain yield and photosynthetic rates of maize hybrids under field conditions.