Chiling Sensitivity of Several Vegetables by Means of Arrhenius Equation

Abstract

Chilling sensitivity of vegetables was investigated by means of Arrhenius equation of respiratory rate of whole and tissue slices or plugs, dehydrogenase activity of tissue slices and rate of potassium ion leakage from tissue slices.
1) Arrhenius plots of respiratory rate of chilling sensitive vegetables i. e. cucumber, eggplant and winter squash fruits, snap beans and sweet potato roots showed break points at the critical temperatures ranging from, 6.7°C to 10°C. These break points corresponded approximately with the critical temperatures for chilling injury of these vegetables. The Arrhenius plots showed different shapes for different species and cultivars of vegetables. Arrhenius plot of respiratory rate of potato tubers which is chilling-insensitive also showed a break point at nearly 10°C, giving a different shape of Arrhenius plot from those of chilling-sensitive vegetables.
2) Break points were observed at the critical temperatures in the Arrhenius plots of respiratory rate of tissue slices or plugs of chilling-sensitive vegetables i. e. cucumber and tomato (immature and ripe) fruits. Temperatures of break point corresponded approximately with the critical temperatures for chilling injury of these vegetables. The different shapes of Arrhenius plots were observed in the case of cucumber and tamato fruits. On the other hand Arrhenius plot of respiratory rate of tissue plugs of carrots (chilling-insensitive) showed a linear line, but that of radish roots (chilling-insensitive) showed a break point at a chilling temperature.
3) Arrhenius polts of dehydrogenase activity in tissue slices of sweet potato roots and potato tubers measured with the TTC.reagent showed break points at nearly 10°C. Arrhenius plot of dehydrogenase activity of potato tubers showed a marked change in the activity at the critical temperature in spite of chilling-insensitive.
4) Arrhenius plots of rate of potassium ion leakage from tissue slices of chilling-sensitive vegetables i. e. cucumber, eggplant, tomato and winter squash fruits, snap beans and sweet potato roots showed break points at chilling temperatures ranging from 6.7°C to 12.5°C. These temperatures at break corresponded approximately with the critical temperatures for chilling injury except winter squash fruit. Higher rates of potassium ion leakage were observed at lower temperatures below the break point. Arrhenius plots of rate of potassium ion leakage from tissue slices of potato tubers and radish roots (chilling-insensitive) showed break points at relatively high temperatures, and that of carrot roots (chilling-insensitive) showed a break point at a chilling temperature.