Effect of soil applied B and Zn on boll retention, yield and fiber quality of Bt. cotton

Alkaline calcareous soils of Pakistan with high pH and low organic matter are becoming deficient in B and Zn. Their deficiency is hampering the yield of various field crops. The losses due to the deficiency of one or both of these nutrients are more pronounced in rice, maize and cotton crops. It is evident that cotton, a cash crop of Pakistan, has been facing problem regarding flower and boll shedding, low quality and productivity due to B and Zn deficiencies. To address this problem an experiment was conducted at agronomic research area, University of Agriculture, Faisalabad, during kharif season 2015 to study the effect of soil applied Band Zn on boll retention, yield and fiber quality of Bt. cotton. Experiment was laid out in randomized complete block design with factorial arrangement. Treatments comprised of soil application of B @ 0, 0.75, 1.5, 2.25 kg per ha and Zn @ 0, 2.5, 5.0, and 7.5 kg per ha. Experiment was replicated thrice with a net plot size of 4.5 x 3 m. Data regarding yield and fiber quality were recorded using standard procedures. Data were statistically analyzed using Fisher's analysis of variance technique by using statistix software and the treatments' means were compared by using Tukey's HSD (Honestly significant difference) test at 5% probability level. The results showed that days to first floral bud (square) initiation, appearance of first flower, number of monopodial and sympodial branches, number of bolls per plant, number of infested bolls, boll retention percentage, number of nodes and height up to first fruiting branch, average boll weight, plant height, seed cotton yield per plant and per hectare were affected by soil applied B and Zn. An increase of 15.58% with benefit cost ratio (1.47) was obtained by application of 2.25 kg per ha, B with combination of 5 kg Zn per ha. All fiber quality traits except ginning out turn (which was affected by both B and Zn) were affected only by B.