ELECTROLYTE LEAKAGE OF AGING POTATO-TUBERS AND ITS RELATIONSHIP WITH SPROUTING CAPACITY

With advancing physiological age of potato tubers an increase in elect rolyte leakage from tuber tissue was observed for various seed lots. T his increase was most marked after tubers exhibited sprout growth and corresponded with a decline in tuber water content. Leakage increased minimally with storage time when sprouting was prevented or limited by either dormancy, low storage temperature, or frequent desprouting. Sp routing capacity of tubers increased to a maximum and then declined wi th storage time. This decline coincided with the increase in electroly te leakage, suggesting that membrane integrity was one determinant in vigour of seed potato tubers. The pattern of electrolytes leaking from tuber tissue could be described by a function composed of a saturable and a linear component, suggesting two different sources contributing to the leakage. The saturable component, expected to reflect membrane integrity, was most responsive to aging treatments.