Abstract: In present study, the components including the contents of ascorbicacid (AsA) , glutathione(GSH) , oxalic acid (OA) , tartaric acid ( TA) and hydrogen peroxide (H₂O₂) and some enzymes activities related with AsA metabolism, were investigated during the growth and development of kiwifruit (Actinidia deliciosa ‘Qinmei’). The results showed that AsA content per gram of fresh fruit increased significantly and reached the maximum at the 30 th day after anthesis (DAA ) , then decreased and maintained essentially constant after the 75 th DAA. The ascorbicacid content per fruit increased significantly and reached the maximum at the 45 th DAA, and then maintained essentially no change to ripe period. It shows that the AsA is mainly accumulated during the fruit cell division stage. Glutathione was accumulated continuously before the
120 th DAA, and the accumulation speed was the fastest in young fruit period. As possible products of AsA degradation, OA showed a similar changes with H₂O₂ content and ascorbate peroxidase (APX) activity during kiwifruit development, which was decreased fast in the fruit early fast development period before the 30 th DAA and was no clear change to maturation, but changes of TA contentwere similar pattern with AsA content. The
activity of ascorbate oxygenase (OA) which can led to oxidation of AsA is similar with activities of monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR) used to recycling oxized ascorbate to AsA during the development, which showed a clear increase before the 60 th DAA, then decreased fast and maintained a low level during the fruit maturation period.

Key words: kiwifruit, fruit, ascorbate, metabolites, enzyme activity