The Effect of Vegetative Ground Cover and Ethylene Degreening on ‘Valencia’ Rind Pigments1

Abstract

Abstract The influence of vegetative ground cover which lowers soil temperature was evaluated on regreening of fruit of ‘Valencia’ [Citrus sinensis (L.) Osbeck] orange. Carotenoid content of the rind increased to a maximum in March and then declined at each subsequent sampling. Chlorophyll content declined to a minimum in February, then increased slightly through May and increased markedly during June and July. Cartenoid content was higher and the chlorophyll content lower in the rind of fruit from the ground cover plots than in fruit from the bare-ground plots. Ethylene degreening for 5 days improved color index values of regreened ‘Valencia’ oranges; however, the color of fruit direct from the ground cover plots was superior to the color of fruit from the bare ground plots after degreening. Postharvest, regreened ‘Valencias’ showed no significant loss of chlorophyll or changes in carotenoids in air at 20°C. Exposure to ethylene caused a loss in chlorophyll, but the rate of loss was slower and the final chlorophyll levels after 8 days degreening with ethylene were relatively high compared with other citrus cultivars given similar treatment.