Effect of a limited water input on root growth, water use and grain yield of wheat

Abstract

Abstract Wheat ( Triticum aestivum L.) was grown on a sandy loam soil to study the effect of different methods of applying a limited quantity of water on root growth, water use and grain yield. Nitrogen fertilizer was broadcast or drilled to 15 cm depth to study the interaction of N-supply with water utilization. About 14 cm of water (enough to charge the soil to field capacity) was applied as a single pre-sowing irrigation (W 1 ); half applied as pre-sowing irrigation and half 30 days after sowing (W 2 ) or 80 days after sowing (W 3 ). A fourth treatment (W 4 ) was given 14 cm of water before sowing and a further 7 cm 30 days after sowing. Whether the soil reservoir was partially or completely filled with water at sowing did not affect root growth at the 56-day sampling. An irrigation at the nodal root initiation stage (30 days after sowing)_promoted overall root growth. Grain yield, rooting density to 120 cm depth and water use were greater with drilled than with broadcast nitrogen. Grain yield and rooting density were highly correlated. Water use increased with the amount of water applied but water use efficiency decreased. Efficiency was higher with early application of a given amount of water.