EFFECT OF FRUITING BRANCH/SQUARE REMOVAL ON BT COTTON UNDER DIFFERENT NITROGEN RATES

Removal of early fruiting branches with optimum nitrogen dose caused more source and no sink at early growth stages leading to delay in onset and progression of senescence in Bt cotton (Gossypium hirsutum L.). Field trials were conducted at Students’ Farm, University of Agriculture, Faisalabad, during 2011 and 2012. Experiments were laid out in a randomized complete block design (RCBD) with factorial arrangement using three replications. Study comprised of manual alteration of plant architecture i.e. F1: no fruiting branch removal, F2: removal of first fruiting branch, F3: removal of first and second fruiting branch, F4: removal of all squares (floral bud) from first fruiting branch, F5: removal of all squares from first and second fruiting branch; and nitrogen rates i.e. N1: 175, N2: 225 and N3: 275 kg ha^-1. More monopodial and sympodial branches per plant were recorded in F5 and F3 with higher and medium level of nitrogen application while minimum was recorded in F1 at all levels of nitrogen. Increasing nitrogen application increased total bolls per plant and cotton yield to highest level in F3 and F5 against lowest in control at all levels of nitrogen. Potassium concentration in leaf increased with increasing nitrogen application in F3 and F5 treatment while in F1, F2 and F3 medium and higher nitrogen application was at par with each other. Ginning out turn, fiber length, seed oil and seed protein content were influenced by fruiting branch or square removal but difference was less. Increasing nitrogen improved seed oil and protein content and fiber quality (length, strength, fineness, elongation etc.)