INFLUENCE OF CHILLING ON POTATO-TUBER RESPIRATION, SUGAR, O-DIHYDROXYPHENOLIC CONTENT AND MEMBRANE-PERMEABILITY

The response of four potato cultivars to various temperatures was evaluated in respect to respiration, sugar and phenolic content, and ion leakage from cut tissue sections. Respiration decreased with decreasing temperature from 20° to 0°C but after 24 hours at 0°C began to increase and reached a maximum after 10 days at 0°C, then drifted downward. No distinct break in an Arrhenius plot of the respiration data from 20° to 0°C was observed. Reducing and non-reducing sugars did not change initially between 20° and 0°C and did not increase until after 6 or 7 days at 0°C. The magnitude of the increase in sugars varied between cultivars. Only one cultivar significantly increased in phenolic content during chilling. Ion leakage remained constant from 20° to 0°C then showed a transient increase within 24 hours at 0°C. A sustained increase in leakage did not occur until after 10 days at 0°C. Cultivars varied in the rate and magnitude of the increase. The respiratory rise could not be attributed to an increase in sugar content or an increase in membrane permeability. Also, the initial increase in sugars preceded the sustained increase in ion leakage. Differences observed between cultivars in the parameters measured were not considered sufficient to explain differences in chilling sensitivity. © 1979 Springer.