Effect of Bag Removing with Reflective Film Mulching Before Harvest on Fruit Coloration and Expression of Anthocyanin Related Genes in Peach

Appearance quality is the main element forming the fruit quality. Both bagging and reflective film application can improve appearance comprehensive quality. In order to determine the effects of bagging and reflective film on peach fruit coloration, this study explored the effects of applying reflective film before harvest on fruit appearance quality of peach (Prunus persica), and discussed the influencing mechanism on fruit coloration. Yellow outside and black inside double-layer bags were removed from fruit twelve days d before harvest. Peel color, pigment content, enzyme activity as well as the gene expression related to fruit coloration of a well-colored and late-ripening peach cultivar ‘Xiahui 8’ with different treatments (non-bagging with non-reflective film mulching, debagging with non-reflective film mulching, debagging with reflective film mulching) were researched. The results showed that both debagging with non-reflective film mulching and debagging with reflective film mulching could significantly improve red and green color difference value (a*), a*/b* (b* is yellow and blue color difference value), chroma (C), anthocyanin (Ant) content and reduce hue angle (h), while debagging with reflective film mulching had higher Ant content than debagging with non-reflective film mulching (P < 0.05). The two treatments up-regulated the transcript level of anthocyanin biosynthetic related genes (UFGT, CHS) at the beginning of the experiment, however, the expression of DFR, LDOX and F3H were enhanced along with the testing process. A downward trend on peel phenylalanine ammonia lyase (PAL) activity of non-bagging with non-reflective film mulching was observed during the experiment, however, the peel PAL activity of the other two treatments first increased and then decreased. What’s more, peel PAL activity of debagging with reflective film mulching was higher than debagging with non-reflective film mulching. These results suggested that Ant synthesis in the peel was the result of cooperation among several genes, and debagging with reflective film mulching had better effect on promoting Ant accumulation than debagging with non-reflective film mulching.