Effect of irrigation water and nitrogen fertilizer on the yield, quality and water productivity of potato crop in drip irrigation (tape) method

In order to investigate the effects of irrigation water and Nitrogen fertilizer on the quantity and quality charactristics of potatoes under drip irrigation, a two-year field experiment was conducted in Agricultural and Natural Resources Research Center of Semnan province (Shahrood). The experiment was conducted based on split plots in a randomized complete block design with three factors and four replications. The design factors were: 1- water rates (75 and 100 percent of requirement water) 2- rates and methods application of nitrogen (60, 80 and 100 percent requirement nitrogen with fertigation method and 100 percent requirement nitrogen with traditional method) 3- planting arrangement (35 and 45 cm), and a control treatment. The experiment was performed using a split factorial plot design (planning arrangement as main plots and water-nitrogen rates as sub plots). The amount of requirement water irrigation was determined by penman-mantith method and metrological data in tape irrigation method, also requirement nitrogen fertilizer was used by fertigation method until to before of flowering duration. Irrigation period was used 3-day. The results showed that the effect of irrigation water on the nitrate concentration of the tubers was significant. Nitrogen concentration in the irrigation water levels 75% and 100% were 310 and 287 ppm Respectively. Also, the results showed that there was a significant difference between nitrogen concentration in fertilizer treatments. The accumulation of nitrate concentration in the fertilizer treatments of 100, 80 and 60 (in drip irrigation method) was 339, 312, 258, respectively. And in the fertilizer treatment 100% with a traditional method was 289 ppm. The effect of water treatments on water use efficiency have significant. The water use efficiency were obtained at 75 and 100 requirement water 3.05 and 2.82 respectively. The 80% Nitrogen fertilizer (fertigation), 75% irrigation water and 45 cm planting distance as the best treatment was selected.