EFFECTS OF ETHEPHON APPLICATIONS ON THE RIPENING OF HAYWARD KIWIFRUITON THE VINE

Effects of ethephon application on the fruit ripening of 'Hayward' kiw ifruit [Actinidia deliciosa (A. Chev.) C. F. Liang and A. R. Ferguson var. deliciosa] on the vine were investigated. In 1990, when 200 ppm e thepon (dissolved with 50% ethanol) was applied at approximately 6-, 5 -, 4-, 3-, 2- and 1-week prior to commercial harvest, the 4- and 3-wee k treatments made the fruits edible. Brix, flesh firmness, and titrata ble acidity of the fruits were about 13%, 0.6 similar to 1.2 kg/cm(2) and 1.1 similar to 1.2%, respectively. On the other hand, 50% ethanol application was ineffective on fruit ripening. When ethephon was appli ed at various concentrations 3 weeks before commercial harvest, the 50 and 100 ppm treatments were ineffective on fruit ripening, whereas th e 500 ppm treatment hastened fruit ripening more than the 200 ppm trea tment. In 1991, when fruits were treated with 200 ppm ethephon, they d id not ripen as fast and uniformly as they did in 1990. We attribute t he difference to the lower air temperature and shorter duration of sun shine during the 1991 experiments. From the above results, we postulat ed that the air temperature and duration of solar radiation after ethe phon application strongly affect the kiwifruit ripening on the vine.