Response of cotton (Gossypium hirsuhrm) to split application of nitrogen and weed control methods

Abstract

Field experiments were conducted during 1999-2000 and 2000-01 in a split plot design to study the effect of split application of nitrogen and weed control strategies on weeds, growth and yield of cotton (Gos~ypiumhi rsutunl L.). The 3 N applications, namely 25% at sowing + 50% at squaring and 25% at flowering; 25% at sowing + 25% at first inigation and 50% at flowering; 15% at sowing + 15% at first irrigation + 35% at squaring and 35% at flowering. Six weed control methods included 2 manual hoeings at 3 and 6 weeks after sowing, 1 hoeing at 3 weeks and 1 earthing-up at 6 weeks, Smetolachlor ( 2.4 kg a.i./ha as pre-plant), S-metolachlor (2.4 kg ailha as pre-plant) + 1 hoeing at 6 weeks, S-metolachlor (2.4 kg a.i.ha as pre-plant) + 1 earthing-up at 6 weeks and weedy check (control). Dry weight of weeds was significantly minimum (81.18 g/m2) with 15% N at sowing + 15% at first irrigation + 35% at squaring and 35% at flowering. Different weed-control methods generally resulted in low dry weight of weeds than the weedy check and consequently plants had more leaf area index. Total bolls producedlplant (19.5 1-30.59), average boll weight (2.36-2.63 g) and ginning outturn (39.75-40.80%) was significantly more in weed-control methods than the weedy check. Two hoeings at 3 and 6 week resulted in maximum seed-cotton yield (2 160.5 kgha) and lint yield (889.7 kgha). This treatment gave a maximum of 87% increase in seed cotton yield over weedy check. Seed cotton yield, ginning outturn and lint yield were not influenced by split nitrogen application.