Growth And Yield Response Of Cotton To Various Agronomic Practices

Appropriate agronomic practices like cultivar selection, planting date, plant density, and nitrogen management have a profound effect on the development and final outcome of the crop. Two field experiments to evaluate the growth and yield response of cotton (Gossypium hirsutum L.) to various agronomic practices were carried out on a loam soil at Post Graduate Agricultural Research Station, University of Agriculture, Faisalabad, during the year 2007 and 2008. In first trial, response of three different cotton varieties (CIM-496, MNH-786 and FH-113) to three sowing dates (1st week of May, 4th week of May and 3rd week of June) and three plant spacing (22.5 cm, 30.0 cm and 37.5 cm) was evaluated. Results revealed that number of monopodias and sympodias per plant, plant height, height to node ratio, number of main stem nodes, number of bolls per plant, boll weight, seed cotton yield per plant and seed cotton yield per hectare differed significantly between sowing times, varieties and plant spacings but plant population was significantly varied only by varying plant spacing. Plant spacing did not influence significantly cotton leaf curl virus (CLCuV) infestation and earliness parameters. The ratio of CLCuV effected plants increased with delay in planting as early sown cotton (1st week of May) up to 90 days after sowing resulted in low virus attack (16.6% in 2007 and 14% in 2008) compared to 100% virus infestation in late sown cotton (3rd week of June) during both the years. Cultivar FH-113 proved to be more resistant to virus attack than other varieties. Cotton grown in 1st week of May had higher seed cotton yield (2796 and 2521 kg ha-1, during 2007 and 2008, respectively) at wide plant spacing (37.5 cm). Whereas, cotton sown in 3rd week of June gave higher seed cotton yields at 22.5 cm plant spacing in 2007 with value of 778 kg ha-1 and at 30 cm plant spacing in 2008 giving 831 kg ha-1. Averaged over sowing time, the cotton Cultivar FH-113 produced significantly highest seed cotton yield (2389 kg ha-1 and 2000 kg ha-1, during 2007 and 2008, respectively) at wide plant spacing whereas both CIM-496 and MNH-786 gave similar yields at wider and normal plant spacing. Leaf area index (LAI), leaf area duration (LAD), total dry matter (TDM) production and crop growth rate (CGR) were also increased with early sowing and close plant spacing. Fiber quality parameters were not influenced significantly by sowing time or plant spacing. Therefore, farmers should sow FH-113 at 37.5 cm spacing for early sowing while for late sowing plant spacing should be 30 cm to have higher seed cotton yield. In second experiment four nitrogen levels (0, 60, 120 and 180 kg ha-1) were applied at three inter row spacings (60, 75 and 90 cm). Both the factors significantly influenced monopodias and sympodias per plant, plant height, main stem nodes, height to node ratio, number of bolls per plant, boll weight, seed index, lint index, seed cotton yield per plant and seed cotton yield per hectare but fiber quality traits were not significantly affected. Leaf area index, leaf area duration, total dry matter production and crop growth rate also increased with increased nitrogen level and decreased row spacing. The maximum seed cotton yield (2106 and 1936 kg ha-1 in 2007 and 2008, respectively) was recorded in 75 cm row spacing due to more number of bolls m-2. Similarly, highest seed cotton yield (2197 and 2032 kg ha-1 in 2007 and 2008, respectively) was produced by applying 180 kg N ha-1 which was also statistically similar to 120 kg N ha-1 in both experimental years. For economic seed cotton yield cotton should be sown on 75 cm spaced rows with 120 kg ha-1 of nitrogen. Key Words: Gossypium hirsutum, planting date, plant spacing, cotton varieties, nitrogen, row spacing, seed cotton yield and fiber quality traits.