Effect of Water Stress and Nitrogen Fertilizer on Yield and Water Productivity of Potato

Water stress, as the most important non-biological stress, has many undesirable effects on nutrients uptake, growth, and yield of higher plants. Nutrient such as nitrogen are effective against water stress and proper usage of nitrogen can prevent drastic reduction of yield under water stress conditions. This study was conducted to evaluate the combined effects of nitrogen and irrigation on the yield and quality of potato (Solanum tuberosum L.). The study was performed as a split-block based on randomized complete blocks design with factors of irrigation at four levels (0-3, 3-6, 6-9 and 9-12 meters’ distance from the main line source), and nitrogen at three levels (90, 135, and 180 kg per ha) using three replications and line source sprinkler irrigation system. Irrigation water of each level was measured by boxes that were fixed in the middle of each plot. The statistical analysis of results was done by the method described by Hanks. The results showed that application of nitrogen significantly increased yield, stem height, leaves number, water productivity, and leaf and tuber nitrogen concentration. Water deficit decreased yield, stem height, leaves number, and water productivity. The two-way interaction of nitrogen and irrigation was not significant on the measured attributes. The best treatment for water productivity (3.91 kg/m3 water) was using 621 mm irrigation and 180 kg N per ha. The highest amount of potato yield (42158 kg/ha) was obtained from application of 180 kg/ha nitrogen and 811 mm irrigation water.