EFFECT OF NITROGEN AND WATER-UPTAKE ON YIELD OF WHEAT

For 2 years, field experiments were conducted to study the direct and interactive effects of water and nitrogen uptake at different growth stages on grain yield of wheat, grown on coarse textured alluvial soil of Ludhiana. Twelve treatments comprising 3 irrigation regimes and 4 rates of N were imposed. The N and irrigation regimes showed significant interaction, especially during the drier year. Grain yield was better explained with water uptake and N uptake, when partitioned over different growth stages than with total uptake. The sensitivity factor for water uptake was higher at the reproductive stage (lambda = 1.60) than at the vegetative (lambda = 1.05) and maturation (lambda = 0.38) stages. Contrary. yield was more sensitive to N uptake during the vegetative stage than the reproductive and the maturation stages. Sensitivity of grain yield to water uptake was higher at higher N application rates. Yield predictability was much better (R2 = 0.98) when N and water uptake at different growth stages were combined.