INFLUENCE OF LIFTING TIME , DURATION AND SHADING ON QUALITY CHARACTERISTICS AND STORABILITY , OF POTATO*

Abstract

Potato tubers Solatium tuberosum L. cv. Desire produced form the spring seasons of 2001 and 2002 , were stored in the Storage Unit , Dept. of Horticulture . Tubers were lifted either , early morning , mid-day or in the evening , then stored either immediately after lifting or left for one , two , or three hours in the field under shade or without it. Results indicated that lifting tubers in the early morning and at the evening significantly decreased sun-sca!d disorder to 8.97% and 7.28% in the first season and to 3.72% and 3.35% in the second season. At the same time , the thickness of the damaged tissues caused by sun scald was decreased to 4.02 and 4.11 mm for the second season. However , the percentage of this disorder significantly increased to 16.25% and 10.21% when tubers lifted in the mid¬day for both seasons , respectively . The thickness of damaged tissues was 14.22 mm for the second season. Lifting tubers at the early morning and mid-day significantly increased each of sprouting to 11.99% and 10.68% in the first season and to 13.60% and 12.42% in the second season , weight loss to 3.93% and 4.02% in the first season and to 2.69% and 2.94% in the second season. Lifting tubers in the evening time , significantly reduced decay to 3.93% in the first season , but lifting tubers early morning in the second season significantly decreased decay to 3.13% . However , lifting tubers at the mid-day significantly increased sprouting to 12.39 % and 15.02% , weight loss to 4.53% and 3.21% , decay to 8.68% and 6.03% for both seasons , respectively . Concerning the duration of tubers lifted in the field , results indicated a significant decrease in sun scald tubers to 0.13% in the first season and there was neither disorder nor damaged in the thickness of tuber tissues when tubers stored immediately . Tubers left for three hours in the field significantly increased sun scald disorders to 6.74 and 5.43% for both seasons in which the thickness of damaged tissue was 9.75 mm. Shading tubers significantly decreased each of weight loss to 3.99 and 2.77% , tubers decay to. 5.66% and 2.86% as compared with unshaded.