REDUCED SENSITIVITY TO ETHYLENE AND DELAY ED RIPENING IN KIWIFRUIT

Some kiwifruit growers notice that kiwifruit markedly differs in the s ensitivity to ethylene treatment for artificial ripening, depending on the origin. However, it remains to be scientifically demonstrated whe ther it is true. Therefore, in order to study the variation in the sen sitivity to ethylene, 26 samples of kiwifruit were collected from the main kiwifruit-producing districts in all of Japan and were held for r ipening in an ordinary commercial tray with an ethylene generator at 1 5 degrees C. Eighteen out of the samples, which seemed to be sensitive to ethylene treatment, softened and ripened in the presence of 10-20 mu l . l(-1) of ethylene produced from the ethylene generator, but the rest (8 samples), less sensitive, didn't ripen and produce the ripeni ng-related ethylene. The reduced sensitivity of the samples to ethylen e was quite reproducible even under the different conditions with doub led quantity of the ethylene generator at 20 degrees C. These results suggest that such less sensitive kiwifruit requires more drastic ethyl ene treatment conditions for ripening.