Nitrogen triggered improvements in growth, net assimilation, allometric traits and yield of Bt. cotton genotypes

Nitrogen (N) management and poor vegetative growth are chief deterrents to accomplish yield potential in cotton. Moreover, genotypes also differ on the basis of N mediated growth and leaf biomass accumulation. An experiment was conducted to optimize N rates for varying genotypes to improve leaf area, leaf area index, leaf area duration and net assimilation rate. Experiment was conducted at Agronomic Research Area, University of Agriculture Faisalabad, Pakistan during 2014. Experiment was laid out in Randomized Complete Block Design with factorial arrangements with combinations N1 × C1, N1 × C2, N1 × C3, N2 × C1, N2 × C2, N2 × C3, N3 × C1, N3 × C2, N3 × C3 and replicated 3 times. Comparatively, more leaf area duration, net assimilation rate, boll maturation period, crop growth rate, plant height, total and opened bolls per plant and seed cotton yield per plant were observed with 250 kg N ha-1 over control. While, genotypes FH-142 and MNH-886 depicted significant enhancement in yield and delay in senescence related attributes than FH-114for most of instances. However, genotype MNH-886 depicted more promising results than other genotypes on the basis of evaluated attributes. Conclusively, N application enhanced growth, leaf biomass accumulation and yield related attributes. Comparatively more N triggered improvement in yield and allometric traits was observed for genotype MNH-886 than other cultivar