Abstract:

In order to evaluate the injures and responses of the anti-oxidation of mango fruits under two different doses of enhanced UV-B radiation treatments, the adult trees of the variety ‘Tainong No. 1’ in the field were treated with enhanced UV-B radiation at the levels of 24 kJ/(m ²·d) and 96 kJ/(m ²·d), and those with natural sunlight were used as the control (CK). The dynamic changes of physiological and biochemical indexes related to plant yield, fruit quality and physiological damage, antioxidant protection mechanism, etc. were observed. The results showed that the yield per tree and single fruit weight of 96 kJ/(m ²·d) was significantly decreased compared with CK, and the fruit soluble sugar was decreased, titratable acid content was increased, and then the sugar-acid ratio was decreased, resulting in the fruit quality was worse. The content of MDA in the pericarp of two UV-B radiation treatments was not significantly different from CK, but the flesh was significantly higher than the CK. The contents of vitamin C and unknown compounds in pericarp treated with 96 kJ/(m ²·d) were significantly higher than the CK, while the POD activity was significantly lower than the CK, and there was no significant effect on the activity of other antioxidant enzymes and content of reductive protective components. The antioxidant enzyme activity and reduced GSH content of the flesh treated with two UV-B radiations increased first and then decreased with time. Compared with CK, the activity of SOD and CAT in the flesh treated with UV-B radiation were significantly decreased. POD activities, flavonoids and reduced GSH contents in the flesh treated by 96 kJ/(m ²·d) were significantly lower than the CK, while POD activities treated by 24 kJ/(m ²·d) showed no significant difference from CK. Flavonoids and reduced GSH contents was significantly lower than the CK only in the post-ripping stage, while polyphenol contents was almost unaffected. It can be seen that enhanced UV-B radiation [96 kJ/(m ²·d)] caused damage to the tree body and flesh, but no damage to the pericarp.

Key words: enhanced UV-B radiation, mango fruits, injures, anti-oxidation