关键词: 枇杷, 果实, 有机酸, 酶代谢酶, 反光膜

Abstract: Effects of reflecting film mulch around tree trunks on titratable acidity（TA），organic acid content and acid-metabolizing enzyme activity in the pulp during the fruit development and total soluble solid（TSS）content in the ripe pulp were investigated，using 15-year-old‘Jiefangzhong’loquat[Eriobotrya japonica（Thunb.）Lindl.] trees. Reflecting film mulch significantly increased ripe pulp TSS content and reduced its TA. At the early stages of fruit development，the increase in both TA and malate content was faster in reflecting film-treated pulp than in control，and reflecting film-treated pulp had higher TA and malate content；At the later stages，the decrease in both TA and malate content was faster in reflecting film-treated pulp than in control，and reflecting film-treated ripe pulp had lower TA and malate content. Malate was the major organic acid determining ripe pulp acidity. Reflecting film mulch induced decrease in ripe pulp acidity mainly resulted from the reduction in malate content. At the early stages of fruit development，the increase in both phosphoenolpyruvate carboxylase（PEPC）and NAD-malate Dehydrogenase（NAD-MDH）activities and the decrease in NADP-malic enzyme（NADP-ME）activity were faster in reflecting film-treated pulp than in control，and reflecting film-treated pulp had higher PEPC and NAD-MDH activities and lower NADP-ME activity；At the later stages，the decrease in both PEPC and NAD-MDH activities and the increase in NADP-ME activity were faster in reflecting film-treated pulp than in control，and reflecting film-treated ripe pulp had lower PEPC and NAD-MDH activities and higher NADP-ME activity. The reduction in malate content in reflecting film-treated ripe pulp was probably caused by decreased malate biosynthesis and increased malate degradation.

Key words: loquat, fruit, organic acid, acid-metabolizing enzyme, reflecting film