The experiments were carried out at a private farm in Dakaelte village neighbor the experimental farm of Faculty of Agriculture, Kafrelsheikh University, Egypt during two successive summer seasons  2008 and 2009. The main objective of the research was to study the effect of soil application of different potassium levels (25, 50, 75 and 100 kg K₂O/fed.) and foliar spraying (twice) with K (zero and 0.5% K₂O equal 6 kg K₂O/fed.) on quality (morphological characters and chemical constituents) and storage ability of sweet potato roots cv. Abees. The experimental design was a split-plot with four replications. Potassium sulphate fertilizer was used for soil and foliar application.        The results indicated that, increasing soil K levels from 25 up to 100 Kg K₂O/fed. Significantly increased root diameter, dry matter, total carbohydrates , crude protein, carotene ,vitamin C contents of roots and K content of leaves and roots. Likewise, increasing K levels up to 75kg K₂O/fed. significantly increased total sugars content of roots. On the contrary, raising K levels from 25 up to 100 significantly decreased root length, root shape index, (L/D ratio), nitrate content, total weight loss   (% )and decay percentage of roots and retarded sprouting date root in both seasons. Foliar application of K significantly increased root diameter, dry matter (%) , total sugars , total carbohydrates , crude protein  vitamin C contents of roots and K content of leaves and roots. However, it significantly decreased root length, root shape index (L/D ratio) nitrate content, total weight loss (%) and decay percentage of root and retarded sprouting date of root compared with the control (no spray) in both seasons. K spray did not effect on roots carotene content in both seasons.         The combined interaction between soil K levels and foliar application of K had insignificant effects on quality (morphological characters and chemical constituents) and storage ability of roots in both seasons.