Studies On Effects Of Salicylic Acid On Fruit Softening And Senescence And Its Mechanism Of Actinidia

Kiwifruit (Actinidid) is a kind of berry fruit with specific respiratory climacteric, which can't undergo long time storage and transport under ordinary conditions. So the development of kiwifruit yielding and improvement of economic benefits are restricted. With the studies on effects of Salicylic Acid (SA) on physiological function of plant developing, ft was found that SA has the function of scavenging the hydroxyl radicals and superoxide radical. And SA can restrain the biosynthesis of ethylene. Thus some scientists presumed that SA may be used to keep fruits and vegetables fresh. This is very important to the study on the storage and keeping fresh of kiwifruit. Therefore, nine-year-old Actinidia Chinensis cv. Fengyue and six-year-old Actinidia deliciosa cv. Miliang I were used as materials. Postharvest fruits of 'Fengyue' were soaked in SA solution of different concentration (1.25,2.5,5mmol/L). Preharvest treatment of 1.25mmol/L SA spraying the fruits and leaves and postharvest treatment of immersing fruits in solutions of 1.25,2.5,5 and 10mmol/L SA were applied to 'Miliang I 'kiwifruit. We aim at studying the regulating effects of SA on the softening and senescence of kiwifruit and its mechanism.The results showed that 'Fengyue' kiwifruit, treated by 5mmol/L SA, had better storage quality than any other ones immersed in SA solutions of other concentration, fruit firmness of which was the highest (0.38MPa), and softening fruit ratio of which was the lowest(33.33%) at 101 day after storage(DFS). The good fruit ratio of preharvest 1.25mmol/L SA-treated 'Miliang I ' kiwifruits is the highest(80.56%). And fruit firmness of postharvest-treated ones, soaked in 10 mmol/L SA, was higher (0.59MPa) at 101 DPS.We also found that there were significant differences in the physio-biochemical changes between fruits of the two cuftivars. During cold storage, the respiratory intensity peak of 'Fengyue' kiwifruit didn't appeared untill about 81 DFS; the peak of LOX activity occurred at around 22 DFS. The Amylase activity declined at the beginning of the storage. 22d later, it had the trend to increase with the peak appearing at 61 DFS. The PG activity was very low at the beginning. It gradually reached the peak at about 82 DFS. Whereas, the respiratory intensity peak of 'Miliang I ' appeared at 11 DFS, LOX activity peaked at 22 DFS. Thechanges of Amylase activity had the same trends as that of 'Fengyue' kiwifruit , the lowest point appeared at 22 DPS. Then it increased slowly.S A treatments of proper concentration can restrain the activity of LOX, POD, PG, and Amylase. It also decreased the accumulation of MDA. So SA can prolong the storage time of kiwifruit.