Water use of maize in response to planting density and irrigation

Abstract

This study aimed to quantify the effect of plant population density and irrigation on the water use efficiency (q) of maize crops, with particular emphasis on the partitioning of water use into transpiration (T) and direct evaporation of water from soil beneath the crop canopy (Esc). A field experiment was undertaken using a split-plot design with watering regimes (rainfed and irrigation) as main plots and plant population density (66,667 and 133,333 plants ha−1) as subplots. Evapotranspiration (ET) was determined by monitoring soil moisture content at 7 d intervals using a neutron probe, Esc was measured daily using microlysimeters, and T was calculated as the difference between ET and Esc. An increase in planting density increased q by 24% under irrigation but reduced q by 17% under rainfed conditions. Esc was 4% less, and T was 9% greater at the highest plant population density owing to a larger crop leaf canopy. Irrigation increased both Esc and T by 41%. Neither Esc nor T were affected by the interaction between population density and water regime. The increase in q at high planting density under irrigated conditions was due to an increase in transpiration efficiency (TE) and a decrease in Esc, while the decrease in q under rainfed conditions was as a result of the predominant decrease in TE. Therefore, the water use efficiency of maize was changed through the manipulation of plant population density. © 2005, Taylor & Francis Group, LLC.