Crop Coefficients for Sunflower as Influenced by Water Deficit at Different Crop Growth Subperiods.

A field experiment was conducted in India during 1995-96 and 1996-97 winter season on a sandy loam soil to derive crop coefficients and irrigation requirements for sunflower. The fully irrigated control treatment recorded significantly higher crop coefficient values at all the crop growth subperiods in comparison to other treatments. The variation of crop coefficient was largely a function of actual evapotranspiration deficit at different crop growth subperiods and leaf area of crop.The crop coefficient curve for fully irrigated treatment showed that the crop coefficient value was low (0.385) in the establishment period, increased linearly through vegetative period, and attained a peak value of 1.049 during flowering, seed formation and seed filling period (25-96 DAS). Over the penultimate crop-growth sub period of maturity (99-105 DAS)the Crop coefficient value decreased to a low value of 0.564. The field application of this study revealed that the net and gross irrigation requirements at field inlet and head works were 5469.9 and 9572.2 m3 respectively.