The Response of Yield, Yield Components, and Nitrogen Use Efficiency of Cotton (Gossypium herbaceum L.) to Supplemental Nitrogen Application under Salinity Stress Conditions in Optimum and Delayed Planting Date

In saline condition, addition to salinity stress, nitrogen deficiency is also observed. In order to investigate the response of yield, yield components, and nitrogen efficiency of cotton to supplemental nitrogen application in saline conditions in optimum and delayed cultivation, a factorial experiment in a randomized complete block design with three replications was done in Sabzevar Islamic Azad University in 2017-2018. Factors were: planting date (optimum and late) and nitrogen levels (0, 2.5, 5, and 7.5 kg.ha-1) as a foliar application on the bolling stage as Urea form. Delayed planting reduced the number of bolls per plant (6.59 %), boll weight (17.33%), seed cotton yield (14.70 %), nitrogen uptake efficiency (23.2 %), and nitrogen use efficiency (11.32 %) compared to optimum cultivation. Foliar application of 7.5 kg N.ha-1increased the number of bolls per plant (67.6%), boll weight (47.2%), seed cotton yield (73.2%), nitrogen uptake efficiency (45.1%), and nitrogen use efficiency (41.2%) compared to control. Sprayed due to lack of solution. The highest plant height, number of reproductive branches, lint percentage, lint yield, and agronomic nitrogen use efficiency in optimum planting date and foliar application of 7.5 kgN.ha-1were obtained which was not significantly different from foliar spraying of 5 kgN.ha-1. Nitrogen foliar application could not improve the negative effects of planting delay on yield and yield components of cotton. In general, the results of this experiment showed that the best seed cotton yield can be achieved by planting at the optimum date and spraying 5 kg of nitrogen as a supplement at the beginning of the bolling stage that increases the efficiency of cotton nitrogen consumption in saline conditions.