Physiological and yield responses of cotton (Gossypiumspp ) to urea with NBPT and DCD under different stress conditions

Nitrogen fertilization accounts for a large portion of the costs of cotton production and crops are known to recover only 30-35% of the N fertilizer applied. The use of urease and nitrification inhibitors with N fertilizers has been recommended for increasing plant N use efficiency. The objectives of this study were to evaluate the performance of urea fertilizer with N-(n-butyl) thiophosphoric triamide( NBPT) and Dicyandiamide (DCD) on the physiology, growth and yield of cotton under high temperature, salinity and field conditions. This research consisted of a field study and two growth room studies, one for high temperature and another for salinity treatments. The following five N treatments were used in these studies: untreated control, full recommended N rate with urea, 75-80% of the recommended N rate with urea, 7580% of the recommended N rate with urea plus NBPT, and 75-80% of the recommended N rate with urea plus NBPT and DCD. In addition, a side study was conducted with the objective of analyzing the effect of NBPT with foliar urea application on cotton physiology and yield. The results of the temperature experiment indicated that only the addition of NBPT to urea fertilizer positively affected the physiology and growth of cotton, with no interaction with temperature conditions. Salinity stress reduced plant growth, decreased N assimilation, and increased plant stress response. Addition of NBPT, but not DCD, to urea improved N uptake under low salinity; however, this effect was not observed with increasing salinity. The field study showed that addition of NBPT to urea fertilizer improved cotton N uptake by 17% and N use efficiency by 41%, which resulted in a14% increase in cotton lint yield. However addition of DCD to urea fertilizer was detrimental to the performance of NBPT. In the foliar study the NBPT was effective in inhibiting cotton leaf urease but there was no consistent effect on cotton yields. In conclusion, only the addition of NBPT to urea fertilization was advantageous. Salinity, but not temperature, influenced the effectiveness of NBPT, and in foliar fertilization NBPT did not have an effect on cotton yields.;The mention of trade or company names does not constitute an official endorsement or approval of their product.