CONJUNCTIVE STIMULUS OF IRRIGATION REGIMES FREQUENCY AND MULCHING ON Bt. COTTON

Abstract

Lower unit cost of production and increase in yield by 29% higher yield in Bt. cotton than hybrid cotton pleased the Saurashatra farmers to adopt Bt. cotton on large scale. Cotton in general does not withstand heavy irrigations. Scheduling of irrigation thus become important in cotton since water is valuable, costly and scarce on one hand. Water availability for agricultural use is declining all over the world due to the scarcity of water resource. Irrigation schedule needs proper irrigation regime, frequency under a particular set of conditions. To study conjunctive impact of different mulches (silver black plastic mulch &wheat straw mulch) irrigation regimes (0.6 ET_c, 0.8 ET_c, 1.0 ET_c) frequency (2 days, 3 days and 5 days) on growth and yield parameter of Bt. cotton. An experiment was undertaken consecutively for two years (2013-14 and 2014-15). Irrigation scheduling was done based on actual evapotranspiration measured with help of soil moisture sensors. The control treatment was taken as drip with no mulch. Silver black plastic mulch recorded 22.40% more plant height, 27.83%number of sympodial branches, 26.23% number of monopodial branches, 28.46% number of bolls, 26% mean boll weight and 38.68% more seed cotton yield than to control at 0.8 ET_c and 3 days irrigation frequency. Highest water use efficiency (20.48 kg ha^-1mm^-1), BC ratio (3.2) and Internal Rate of Return (141.52%) was observed under silver black plastic mulch with 0.8 ETc and 3 days frequency of irrigation.