Resources Use Efficiency of Field Grown American Cotton (Gossypium hirsutumL) Under Semi-Arid Environment.

Resources use efficiency of cotton crop was studied under semiarid environmental conditions. Two years field experiments were conducted at the experimental farm, University of Agriculture (UAF) Pakistan, (latitude 31.25o N, longitude 73.09o E, and latitude 184.4 m from sea level), Agronomic Research Area, Postgraduate Agricultural Research Station, University of Agriculture, Faisalabad during the years 2003 and 2004.Variables in the study include viz four irrigation schedules i.e. six irrigations, three irrigations, irrigation at 25 mm potential soil moisture deficit and irrigation at 50 mm potential soil moisture deficit along with seven integrated plant nutrition levels viz. control (N0), 75 - 37.5 – 37.5 kg N-P2O5 – K2O ha-1 (N1), 75-37.5-37.5 kg N- P2O5-K2O ha-1 + FYM (farm yard manure) @ 20 t ha-1 (N2), 75-37.5-37.5 kg N- P2O5-K2O ha-1+ wheat straw@ 5 t ha-1 (N3), 150-75-75 kg N- P2O5-K2O ha-1 ha-1 (N4), 150-75-75 kg N- P2O5-K2O ha-1 + FYM @ 20 t ha-1 (N5), 150-75-75 kg N- P2O5-K2O ha-1+ wheat straw @ 5 t ha-1 (N6); on the leaf area duration and net assimilation of cotton crop. The experiment was laid out in randomized compete block design (RCBD) with three replications. Significantly higher leaf area duration and total dry matter cotton yields were attained under Faisalabad, Pakistan conditions, when cotton crop was planted at 150-75-75 kg N- P2O5-K2O ha-1+ FYM @ 20 t ha-1 along with any of three irrigation schedules viz. six irrigations or irrigation application when there was 25 or 50 mm potential soil moisture deficit. TDM production in I4 (irrigation at 50 mm potential soil moisture deficit) or in other higher integrated plant nutrition levels was due to higher crop growth rate in these treatments. Analyzing crop growth and yield in terms of leaf area duration (LAD) and yields, a strong and positive linear relationship was found. Maximum radiation conversion efficiency of 1.86, 1.86 and 1.88 gMJ-1, respectively in 2003 and 1.82, 1.82 and 1.84 in 2004. The minimum values of 1.21gMJ-1 and 1.19 gMJ-1 were recorded in 2003 and 2004, respectively with I2 (three irrigations).Maximum values of radiation use efficiency (1.99 in 2003 and 1.95 in 2004) were recorded with the treatment N5. The minimum values (1.52 in 2003 and 1.49 in 2004) were observed with N0 (control).