Evapotranspiration and yield response of wheat to irrigation frequency and fertilizer levels

Nutrient status in the root zone regulates the actual evaportranspiration (AET) pattern from the crop field. A field study was thus carried out to evaluate the impact of irrigation frequency (IW/CPE = 1.2, 1.0 and 0.8) and fertilizer levels [100, 50 and 0% of recommended fertilizer (N:P₂O₅:K₂O as 80:40:40 kg ha⁻¹] on leaf area index, crop growth, yield, components of water balance and water use efficiency (WUE) of wheat crop. The experiment was laid out in a split-plot design where irrigation frequencies were assigned to main plot and fertilizer levels were under sub-plot treatments. Magnitude of yield and other crop parameters, moisture content and AET declined temporarily with the decrease in both irrigation frequency and fertilizer levels. The AET poses a strong positive correlation with grain and straw yields. Good matching between potential and actual evapotranspiration was observed. The WUE values increased with the increase in frequency of irrigation. Under wet (IW/CPE = 1.2) regime, highest level of WUE was attained under 50% fertilizer dose. However, under moderately wet or dry condition magnitude of WUE decreased with a decrease in fertilizer doses. A good matching between cumulative values of potential and actual evapotranspiration was observed.