Studies on Chilling Injury of Fruits and Vegetables

Part 1. Chilling Injury of Cucumber Fruits with Special Reference to Permeability of Membrane of Tissues

Abstract

Changes in respiratory rate of the cucumber fruits and in electrolyte leakage from the discs of tissues were investigated at various temperatures in the range between 0°-25°C with the purpose of research on the mechanism of chilling injury.
1. The respiratory rate of intact fruits continued to increase gradually at 0° and 5°C during storage, and the occurrence of pitting which was one of the typical symptoms of chilling injury was observed on the fruit surface at those temperatures after 5 days of storage. However, there was no symptom of chilling injury observed in the fruits stored at 10° and 20°C throughout storage period.
2. While, changes in the rate of leakage of potassium ion and of total ions into the incubation medium from the discs of fruits stored at 10° and 20°C showed a principally constant level during storage. The rate of leakage from the discs of fruits stored at 0° and 5°C started to increase rapidly on the seventh day after storage and reached to approximately twice rate compared with those from 10° and 20°C after 12 days of storage.
3. The rate of potassium leakage from the discs of the tissues was represented according to the Arrhenius equation in the range between 0° and 25°C.
A breaking point was obtained in the figure of Arrhenius plots at the temperatures arround 7°C which corresponded with the critical temperatures for chilling injury. This breaking point in Arrhenius plots of rate of potassium leakage from the tissues of fruits that had been stored at 5°C for 9 days or longer became obscure. The rate of potassium leakage from the fruits tissues increased remarkably after suffering chilling injury.
4. To confirm the above mentioned results, the Arrhenius plots of rate of potassium leakage from the tissues of chilling sensitive plant, bell pepper, and from the chilling insensitive plant, potato tuber, were compared each other.
There was a breaking point in the Arrhenius plots of rate of potassium leakage from the tissues of bell pepper as same as the case of cucumber fruits, but the figure of Arrhenius plots of rate of leakage from potato tuber tissues showed a linear line in the range of temperature between 0°and 25°C.
From the results mentioned above, it may be reasonable to consider that the phase transition in the membrane of tissues of chilling sensitive plants occure at low temperatures and that disintegration of the membranes, e.g. plasmalemma, tonoplast, take place in the cells of the sensitive plants suffered from chilling injury.