Evaluation of cotton establishment methods and zinc nutritionon productivity,zinc uptake, zinc use efficiency and fibre quality of Btcotton (Gossypium hirsutum L.) in Upper Gangetic Plain of India

Abstract A field experiment was conducted during rainy seasons of 2013 and 2014 to evaluate the performance of cotton establishment methods and zinc nutrition on zinc use efficiency, productivity and quality of Bt cotton. The experiment was laid out in split plot design comprising two cotton establishment methods (direct sowing and transplanting) and five zinc-levels (control, 2.5, 5.0, 7.5 kg zinc ha-1 and 0.5% zinc sulphate foliar spray at 60 and 90 days after planting) on cotton. The cotton variety (SP 7007, BG II) was taken under study. Statistically similar seed cotton, lint, seed, stalk and biological yield were recorded under methods of crop establishment. Zinc levels significantly influenced seed cotton, lint, seed, stalk, biological yields and ginning percentage in both the years and application of 5.0 and 7.5 kg Znha-1being at par recorded significantly higher seed cotton, lint, seed, stalk and biological yield over 2.5 kg Znha-1and control. Foliar application of 0.5 % zinc recorded seed cotton, lint, seed, stalk and biological yields on par with 2.5 kg Znha-1and significantly inferior to 5.0 and 7.5 kg Znha-1. On an average, application of 5.0 kg Znha-1recorded 9.2, 14.5, 8.3, 7.6 and 7.1 % increase in seed cotton, lint, seed, stalk and biological yields over control. Cotton establishment methods recorded non-significant in quality parameters, however, by and large improvement in all the quality parameters was observed with increasing level of zinc and highest value of ginning percentage, uniformity ratio, 2.5 % span length, 50 % span length and fibre elongation were recorded with 7.5 kg Znha-1, whereas in case of fibre strength, the highest value was recorded with 5.0 kg Znha-1. Transplanted plots recorded slightly higher zinc content than direct sown plots. The higher content of zinc in cotton seed and fibre was recorded due to effect of 5.0 and 7.5 kg Znha-1, both being at par across the seasons. Transplanted plots recorded slightly higher zinc uptake than direct sown plots. The higher uptake of zinc in cotton seed, fibre and total zinc uptake was recorded due to effect of 5.0 and 7.5 kg Zn ha-1 in both the seasons, which was significantly superior to foliar application, 2.5 kg Znha-1and control. Effect of methods of crop establishment was non-significant on agronomic zinc use efficiency, zinc recovery efficiency, physiological efficiency and zinc harvest index. Increase in level of zinc and foliar spray decreased the agronomic zinc use efficiency.