Nitrogen fertilizer management for enhancing productivity and nitrogen-use efficiency in Bt cotton

Abstract

A field experiment was conducted at ICAR–Indian Agricultural Research Institute (IARI), New Delhi during kharif 2013–14 to study the effect of four nitrogen (N) levels on crop productivity and nitrogen-use efficiency in Bt cotton in a factorial randomised complete block design (RCBD). There were nine treatments, viz. (i) 4-N rates (100, 125, 150, and 175 kg/ha as urea), (ii) two rates of N application at sowing (0 and 30 kg N/ha) and (iii) one absolute control. Significantly higher seed cotton and lint yields were obtained with application of 175 kg N/ha along with basal application of 30 kg N/ha compared to remaining treatment combinations. Total N-uptake, N-harvest index and normalized difference vegetative index (NDVI) of Bt-cotton were significantly higher at 175 kg N/ha compared with rest of N levels. However, highest N-use efficiency indices were recorded with 150 kg N/ha. A strong and positive correlation (r2=0.804-0.835) was observed between yield and NDVI indicating that NDVI could be used for predicting the potential yield of Bt cotton in semi-arid north Indian plains.

Keywords

• Bt cotton
• Correlation
• N-use efficiency
• NDVI
• Productivity