Yield and Yield Components of Potato (Solanum Tuberosum L.) Tuber as Affected by Nitrogen Fertilizer and Plant Density

In order to investigate the effects of plant density and nitrogen fertilizer level on yield and yield components of potato crop (Agria cultivar), a field experiment was carried out in Ardabil, Iran, in 2006. the experiment was factorial in the base of randomized complete block design with three replications. Factors included nitrogen fertilizer level (0, 80, 160 and 200 kg ha-1 as urea) and plant density (5.5, 7.5 and 11 plant m-2). Results showed that increasing nitrogen level up to 80 kg ha-1 led to more tuber yield. The highest yield, number of stolon, harvest index, number of tuber and dry weight of tuber were obtained with application of jointly 80 and160 kg ha-1 nitrogen. Increasing plant density resulted in higher tuber yield, number of stolon, dry weight of tuber and total dry matter yield and decreased harvest index. Increasing nitrogen fertilizer rate up to 160 kg ha-1 increased mean tuber weight and total dry matter yield. To obtain the highest yield and avoid of environmental pollutions, use of 80 kg ha-1 nitrogen fertilizer with density of 11 plant m-2 is recommended