Response of Lettuce (Lactuca sativa L.) to Trickle Irrigation under Different Irrigation Intervals, N Application Rate and Crop Geometry

Field experiments were conducted on the sandy loam soils of Center for Protected Cultivation Technology (CPCT), Indian Agricultural Research Institute (IARI), New Delhi, India during October - February seasons for 2 years (2008-2010) to evaluate the economic feasibility of trickle irrigation in combination with different irrigation intervals, N application rate and crop geometry for lettuce crop. Reference evapo-transpiration for lettuce crop was estimated using FAO-56 Penman-Monteith method. The net irrigation volume (V) was determined after deducting the effective rainfall. The plan of experiment included three crop geometries [45×30 (G1); 30×30 (G2) and 17.5×30 (G3) (Row × Plant spacing in cm)], two irrigation schedules [2 day (I1) and 4 day (I2) interval] and 2 levels of nitrogen application [60 kg ha-1 (N1) and 100 kg ha-1 (N2)]. For both the experiments, three replications were given. The study indicated that 2 day irrigation interval with 100 kg N ha-1 application in 17.5 × 30cm crop geometry gave the highest yield (41.4 t ha-1) with 6 per cent increase in yield as compared to rest of the treatments. The same treatment has resulted into maximum net seasonal income, benefit-cost ratio (BCR) and lowest payback period for both the years, respectively