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 stages leading to delay in onset and progression of senescence in Bt cotton. 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 statistically 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 and fiber quality.