Effects Of Different Pollens On Sugar And Organic Acid, Ascorbic Acid Compositions And Related Enzyme Activities In Apple Fruits

Three apple( Malus domestica) cultivars including Fuji,Gala and Golden Delicious were pollinated before the blooming period with pollens from different pollination trees. The ascorbic acid( As A) metabolism relative enzymes,including ascorbate oxygenase( AAO), ascorbate peroxidase( APX), dehydroascorbate reductase( DHAR),monodehydroascorbate reductase(MDHAR),L- galactono-1,4-lactone dehydrogenase( GalLDH),L-galactose dehydrogenase(GalDH) the fruit composition of sugar and acid, antioxidant enzymes superoxide dismutase(SOD), peroxidase(POD), catalase(C AT) and malondialdehyde(MDA) activity in the fruits were determined every 20 days during fruit development stage. The main results were as follows:(1)The results showed that AsA contents increased significantly during 40-60 days after pollination.The GalLDH activity of the pollinated fruits was significantly higher than that of the control.The GalDH activity of the pollinated fruits was also higher than that of the control even though the enzyme had relatively low activity during fruit development process.The activity of MDHAR and DHAR in the pollinated fruits was relatively higher than the controls during the fruit development stage,while the activity of AAO and APX in the pollinated fruits was lower than the controls,but there were no significant differences in those enzymes activities between the pollinated fruits and the controls. Besides,the activity of AAO,APX,DHAR,and MDHAR maintained a relatively high level at the early fruit development stage,then declined and finally remained stable at a low level.The study suggests that the increase of the synthetase activity leads to the increase of As A contents in the pollinated fruit.(2)Different pollen has different effects on the contents of As A in fruit. But the difference is not significant,and the contents were higher than the CK. During the fruit development stage, the activity of SOD, POD had the same changes with As A accumulation, decreased firstly, then increased, and then decreased. The changes of CAT activity,while the contents of MDA increased at first,and then decreased.. The pollen treated fruitenzyme activity was higher than that of CK,while the MDA content was lower than the CK. In the late stage of the fruit development, total acid content of fruit was less than CK, the oxalic acid and tartaric acid content was higher than that of CK,while the malic acid, citric acid and succinate were less than that of CK. the sugar content is higher than that of the CK, and the fructose and the sucrose content were significantly increased than CK. It suggested that different pollen can increase the content of As A in fruit,and have different effects on the Antioxidation enzyme activity and thecontent of sugar and organic acid at the same time.