Effect of irrigation schedules and nitrogen levels on the yeild of cauliflower through drip irrigation

A field study on fertigation 14 cauliflower (Brassica oleracea var. botrytis Linn.) using drip irrigation system was undertaken with three rates of nitrogen application (100%, 75% and 50%) of recommended dose applied in three splits i.e. 50% of the dose at planting time, 25% at 30 days after planting and remaining 25% at 60 days after planting with three levels of irrigation at (irrigation water to cumulative pan evaporation ratio) IW/CPE= 0.5, 0.75 and 1.0 in fan pad cooled greenhouse and naturally ventilated greenhouse respectively. Various predication models viz. linear, quadratic, square root and three halves governing the relationship between irrigation water, nitrogen fertilizer and the yield in respect of off-season cauliflower were developed. The studies reveal that the yield 120.7 q/ha and 105q/ha of early cauliflower were maximum under irrigation schedule based on IW/CPE=0.5 and 100% of recommended nitrogen dose in both the greenhouses. Square root model was the best prediction model for assessing the impact of irrigation water and nitrogen dose on crop yield, with higher R² value (0.956) in fan pad cooled greenhouse (RMSE-=4.18) and quadratic model with higher R² value (0.901) in naturally ventilated greenhouse (RMSE=5.72). The prediction model indicates that cauliflower shows a declining response to amount of irrigation water having negative regression coefficient. The crop response was positive to nitrogen application in its square root terms indicating its favorable influence on crop yield at higher doses.