M.A. Thesis:

Effect of yield and yield components of cotton using nitrogen fertilizer containing sulfur in saline conditions

In order to evaluate the response of yield and yield components of cotton to liquid nitrogen-sulphur fertilizer under salinity conditions, a factorial experiment based on randomized complete block design with three replications was carried in Sabzevar, Iran. Experimental factors were amount of application of liquid nitrogen-sulphur fertilizer in four levels of control, 1, 1.5 and 2 l/ha and time of foliar application at three levels of foliar application at vegetative growth, foliar application at beginning of reproductive growth and two foliar applications at vegetative growth and beginning of reproductive growth. The results showed that the amount of liquid nitrogen-sulphur fertilizer had significant effect on all of the studied characteristics, except the number of seeds per boll. The application of liquid nitrogen-sulphur fertilizer increased leaf chlorophyll index, plant height, number of lateral branches per plant, number of bolls per plant, cotton yield and biological yield and 1000 grain weight, but decreased the average boll weight and harvest index at high levels of application. The highest leaf chlorophyll index, plant height and 1000 seed weight of cotton were obtained in treatment of 2 l/ha liquid nitrogen-sulphur fertilizer. However, the highest number of lateral branches was produced in the treatment of 1.5 l/ha liquid nitrogen-sulphur fertilizer. There was a significant difference between the different levels of liquid nitrogen-sulphur fertilizer foliar application in relation to plant height, leaf chlorophyll index, number of bolls per plant, cotton yield and average boll weight. The highest plant height and leaf chlorophyll index were observed in two-step foliar application of liquid nitrogen-sulphur fertilizer at vegetative growth and beginning of reproductive growth, which had no significant difference with the treatment of foliar application in vegetative growth stage. The highest number of bolls per plant, cotton yield and biological yield were produced with foliar application of 1.5 l/ha liquid nitrogen-sulphur fertilizer in two stages of vegetative growth and the beginning of reproductive growth, which was significantly higher than the control treatment.There was no significant difference between different foliar application levels of 1.5 l/ha liquid nitrogen-sulphur fertilizer with 1 and 2 l/ha liquid nitrogen-sulphur fertilizer foliar application treatments in vegetative growth stage as well as two-step foliar application of 1 l/ha liquid nitrogen-sulphur fertilizer in vegetative growth and reproductive growth stages in relation to cotton yield. According to the results, foliar applications of 1 l/ha liquid nitrogen-sulphur fertilizer at vegetative growth is recommended for production of optimum yield in cotton under saline conditions.

Keywords: Cotton, salinity stress, nitrogen, foliar application, sulphur