Abstract:

In order to study the photosynthetic characteristics of green apple fruit, photosynthesis in different position of apple fruits and the dynamic variation of photosynthetic capacity as well as pigment contents in Starkrimson fruit peel were investigated at different development stages using Oxygen Electrode System and Spectral Analysis System. The result showed that photosynthetic rate in sun-exposed peel was higher than that in peel on shaded side. In longitudinal direction, the photosynthetic rate of sun-exposed peel gradually decreased from calyx-end peel to stalk cavity. The sun-exposed peel at the middle part of a fruit had an average photosynthesis along the longitudinal direction, which could be used as the representative photosynthesis of an apple fruit. With development of an apple fruit, photosynthetic O₂ evolution rate gradually declined, and chlorophyll content remarkably decreased, but the ratio of carotenoids /chlorophyll increased. At the late stage of green fruit development, the reduced chlorophyll content could decline the absorbed light energy, mitigating photoinhibition of apple fruit peel when the photosynthetic ability decreased greatly, which might be an adaptive mechanism of apple fruits in light environment.

Key words: apple (Malus pumila), green fruit peel, photosynthesis, chlorophyll