Effect of irrigation and nitrogen on yield, yield components and water use efficiency of eggplant

The effects of irrigation interval and nitrogen fertilizer on eggplant ( Solanum melongena L.) in a field trial at Astaneh Ashrafiyeh, Guilan, Iran during 2009 were studied. Experiment was conducted in split plot based on randomized complete block design with three replications. Irrigation levels were the main-plots consist of three irrigation intervals (no irrigation, 6 days interval and 12 days interval). Nitrogen fertilization which included four levels (0, 60, 120 and 180 kg ha -1 ) was assigned to sub-plots. The results of this study show that among irrigation treatments, the highest amounts of all studied traits of eggplant included plant height, fruit length, fruit diameter, number of leave per m 2 , number of fruit per m 2 , water use efficiency (WUE) and fruit yield were observed in 6 days interval irrigation with total water use of 441 (mm). On the other hand, water stress resulted in significant decreases in these characteristics. Results also illustrated that plants that received 120 kg N ha -1 produced the highest fruit yield and yield-determining traits than those in the control treatment. In addition, regarding the interaction effects between irrigation intervals and nitrogen fertilizer, it could be concluded that irrigation of eggplants every 6 days and application of 120 kg N ha -1 resulted in the highest yield and yield attributes. In addition, results of interaction effects comparison indicated that WUE varied from 4.36 to 11.6 kg m -3 and the highest amount of WUE was recorded in plants irrigated every 6 days and received 120 kg nitrogen per hectare. Key words: Eggplant, fertilizer, Iran, irrigation interval