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Field experiments were carried out in a farm neighboring the experimental farm of the Faculty of Agriculture, Kafr El-Sheikh during the two successive early summer seasons of 1998/99 and 1999/2000 to study the effect of K fertilization (as soil application at the levels of 50 and 100 kg. K2O/fed) and foliar spraying with 1% K2O solution (as K-sulphate) once (at 60, 75 or 90 days after planting, DAP), twice (60 and 75, 60 and 75 or 75 and 90 DAP) and thrice (at 60, 75 and 90 DAP) on mineral nutrient elements and their ratios and storage ability (sprouting and weight loss) of potato (Solanum tuberosum L.) tubers cv. Cara.The results indicated that application of K at 50 kg K2O/fed lead to significantly higher tuber N content and sprouting percentage than 100 kg K2O/fed in both seasons. Otherwise, fertilization of K at 100 kg K2O/fed had significantly higher tuber K content and K: P ratio than 50 kg K2O/fed in both seasons. On the other hand, P, Na, N: P and K: N ratios and total weight loss percentage in tuber were not affected by K levels in both seasons.Foliar sprays of K twice at 60 and 75 DAP significantly increased tuber N, P and K: N ratio and decreased N: P and K: N ratios, weight loss percentage and sprouting percentage compared with the other treatments in both seasons. Moreover, tuber K content was significantly increased when the plants were sprayed with K once at 75 DAP or twice at 60 and 75 DAP in the first season, or sprayed with K twice at 75 and 90 DAP or thrice at 60, 75 and 90 DAP in the second season. On the other hand, Na content of tuber was not significantly affected by number and times of foliar K application in both seasons.The interaction between soil applied K levels and number and times of foliar K application had no significant effects on mineral nutrient elements (N, P and Na) and their ratios (N: P, K: N and K: P ratios) and sprouting percentage in both seasons. However, it had significant effects on total weight loss percentage of tubers in the first season and on tuber K content in both seasons.