Two Spring trials were carried out on potato cv. Spunta to investigate the effect of O(K0), 15(K1) and 25(K2) kg K2O/donum and 0(N0), 10(N1), 20(N2) and 30(N3) kg N/donum and their interactions on the crop growth and productivity. Plant height was significantly increased with nitrogen increase, where N3 had the longest plants. K insignificantly increased the height, where K1×N3 and K2×N3 respectively produced the significantly longest plants. Shoot fresh weight was significantly increased with N increment, and K2×N3, where K1 and K2 insignificantly increased it. Yield as g/plant, ton/donum and tubers number/plant was significantly increased by N increase, where N3 and N2 produced the significantly highest yield. K1×N2 and K2×N3 were the highest g/plant or ton/donum, whereas K1×N2 and K1×N3 were the highest tubers number. Tuber >60mm was significantly increased by N, where K was insignificantly effective, and K1×N2 and K2×N3 were the highest. Tuber 35-60mm insignificantly was increased by N, K, K1×N3 and K1×N2. Tuber weight was insignificantly increased by N and K increase, K1×N2, and K2×N3. Tuber specific gravity showed insignificantly changes. Nitrogen increment significantly increased tuber dry matter percentage, where K0×N3 and K2×N3 had the highest percentage. Leaf total chlorophyll was significantly increased with N increase, where N3 and N2 produced the highest pigment. Potassium had no effect, where K1×N3 and K2×N3 were the highest chlorophyll. Leaf petiole N was significantly increased by nitrogen increment, where K was insignificantly effective. K2×N3, K0×N3, and K1×N3 were the significant highest N content. Petiole K significantly increased as K increased, where K2 was the highest significant content. Nitrogen was of insignificant effect on K, where K2×N1, K2×N2, and K2×N3 were the highest leaf petiol K content.
Key words: Leaf; Nitrogen; Potassium; Potato; Tuber; Growth; Yield.
