Direct and Indirect Effects of Light Conditions on Red Coloration of Flesh of ‘Kurenainoyume’ Apple Fruit

Abstract

The direct and indirect effects of light conditions on the development of the red flesh of ‘Kurenainoyume’ apples were examined in order to better understand the reasons for color variations as well as to develop management technologies to improve the flesh color. The amount of anthocyanin in the flesh was significantly correlated with the amount of anthocyanin in the skin, and anthocyanin in the flesh nearest the skin rose with increasing anthocyanin in the skin. LED blue light (450–470 nm) induced anthocyanin accumulation in the flesh of the fruit on the tree, as well as in the detached fruit. Blue light (450–470 nm) was highly effective in stimulating anthocyanin accumulation in sliced flesh, which had been irradiated directly. On the other hand, defoliation and ringing on the fruiting branch before anthocyanin accumulation significantly decreased the amount of anthocyanin in the flesh of bagged as well as non-bagged fruit. These results suggest that anthocyanin accumulation deep in the flesh of the fruit does not depend on light irradiation, but depends instead on photoassimilates. The results also showed that light conditions directly affect red coloration in the flesh near the skin, and indirectly affect anthocyanin accumulation in flesh at deeper positions within ‘Kurenainoyume’ apple fruit.