Irrigation and nutrient effects on growth and water-yield relationship of wheat (Triticum aestivum L.) in central India

Increasing production of wheat from a limited water supply can result from efficient irrigation and nutrient management. A 3-year field experiment was conducted at the Indian Institute of Soil Science, Bhopal, to study the growth, yield, seasonal evapotranspiration (ET) and water use efficiency (WUE), and the water yield relationship of wheat in a soybean-wheat cropping system on vertisols. Three levels of irrigation, viz. 10, no post-sowing irrigation; I-1, two irrigations [crown root initiation (CRI) and flowering stage],- and I-2, three irrigations (CRI, maximum tillering and flowering stage) and three nutrient management treatments, viz. F-0, control (without fertilizer/ manure); F-1, 100 % NPK (100-21.5-24.9 kg ha(-1)); and F-2, 100 % NPK + farmyard manure (FYM-10 t ha(-1)) were tested in a split-plot design with three replication. It has been established (through ANOVA) that the year effect was rather negligible and the interaction effects of irrigation and nutrient management on the growth parameters, ET, yield components, yield and WUE were significant. Plant height, progressive leaf area index, dry matter accumulation and crop growth rate were higher in I2F2, and I2F1 and I1F2 were statistically at par. The seasonal ET increased significantly with the increase in water supply in every nutrient treatment and it was highest in I2F2 and lowest in I0F0. The highest grain yield was obtained in I2F2; and a similar yield was recorded in I3F1 and I2F2. This shows a strong interaction effect between irrigation and nutrients. 2 Yield components, viz. number of ears m(-2), number of grains ear(-1) and 1000-grain weight were significant. The higher number of ears m-2 containing greater number of grains with relatively heavier weights appeared to have contributed to the higher yield in I1F2, I2F1 and I2F2. The highest WUE obtained in I0F2 did not correspond to the highest yield and maximum ET, but a WUE of 10.43 kg ha(-1) mm(-1) in the I2F2 combination corresponded with the highest yield and the seasonal ET requirement was 391.8, which was 137 % greater than the water use at maximum WUE. The ET-grain yield relationship was linear, with a lowest regression slope (i.e. marginal WUE) and elasticity of water production (E-wp) in F-0 and a considerably higher slope and E-wp in F-1 and F-2. As the Ewp is positive and close to one in 100 % NPK treatment, the scope of improving WUE and yield with only inorganic fertilizer is very little, and relatively greater scope exists in the integrated management of organic manure and inorganic fertilizer. The results suggest that integrated nutrient management (100 % NPK + FYM) in conjunction with three irrigations maximized yield of wheat with concomitant improvement in ET and WUE under limited water availability.