| Apple is an indispensable fruit in daily life and well received by consumers,which is rich in nutrients,especially vitamins and minerals.However,fruits of mid-early ripening apple cultivars are not resistant to long-term storage,the decline of apple fruits quality will occur in a short time after harvesting.To delay the ripening and aging process and extend its shelf life as much as possible,it is necessary to establish a safe,efficient,and low-cost method for apple storage and preservation,but it is a key issue that needs to be solved urgently in the process of fruits preservation at home and abroad in recent years.H2S is a signal molecule that regulates plant physiological metabolism and plays an important role in fruits ripening and senescence.In this paper,the postharvest'USA8'and'Starkrimson'apple fruits were used as experimental materials,the physiological characteristics of fruits treated by H2S,ethylene?ETH?and ETH+H2S were compared by using NaHS as the donor of H2S.The main results were as follows:?1?Compared with CK,ETH and ETH+H2S treatments,the decline rate of hardness of the postharvest'USA8'apple fruits in H2S treatment was delayed,the contents of soluble solids,vitamin C and titratable acid in H2S treatment were maintained,the activity of antioxidant enzymes such as SOD,CAT,POD and APX and PAL resistance enzymes of fruits in H2S treatment were effectively increased,however,the activities of PPO,LOX,PG,Cx and other enzymes were inhibited,the rate of·O2-production in fruits was reduced,and the accumulation of H2O2 and MDA was inhibited,too.On the 15th day after harvest,the PAL activity of H2S treated fruits increased by 12.25%compared with CK.At the same time,the activities of PPO,LOX,PG and Cx were inhibited,in the 15th day after harvest,the activities of PG,LOX and Cx in H2S treatment were 82.84%,60.42%and 82.35%of CK,respectively.The production rate of·O2-in fruits treated by H2S was effectively reduced,on the 15th day after harvest,only 88.77%of CK treatment and 91.13%of ETH+H2S treatment.On the 15th day after harvest,the H2O2content and the production rate of·O2-in the fruits treated by ETH+H2S were only 90.16%and80.23%of the ETH treatment.?2?Compared with CK,ETH and ETH+H2S treatments,the decline rate of hardness of the postharvest'Starkrimson'apple fruits in H2S treatment was delayed,the contents of soluble solids,vitamin C and titratable acid in H2S treatment was maintained,the activity of antioxidant enzymes such as SOD,CAT,POD and APX and PAL resistance enzymes of fruits in H2S treatment were effectively increased,at the same time,the activities of PPO,LOX,PG and Cx were inhibited,the rate of·O2-production in fruits was reduced,and the accumulation of H2O2and MDA was inhibited,too.On the 25th day after harvest,the hardness rate of fruits treated by H2S increased by 35.29%and 33.6%compared with that in CK and ETH treatments.The APX activity of apple fruits treated with H2S was higher than that in the CK by 23.77%.The H2O2 content and the production rate of·O2-in the fruits treated by H2S were only 88.68%and68.64%of which in CK treatment.The results showed that H2S can play a significant regulatory role in fruits ripening and aging.H2S can reduce the accumulation of ROS in the fruits,slow down the membrane lipid peroxidation,slow down the rate of fruits hardness decline,improve its disease resistance,etc.,and then it has a good effect on the fresh-keeping storage of apple fruits. |
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