| Kuqa Apricot is one of the famous apricot cultivars in Xinjiang, mainly produced in Xinjiang Kuqa and Luntai. Kuqa Apricot fruit are oval, transparent light yellow color, smooth and hairless with yellow flesh and freestone. They taste mellow and refreshing, sweet and chewy with lingering pleasant flavor. The fruit mature early and are nutritious. However, because of the hot temperature during the harvest season, Kuqa apricot has a short harvest period, highly perishable, and short storage life. The shelf life is usually only3-5d. The difficulty in maintaining keeping quality has greatly restricted the development of Kuqa apricot industry. This study was carried out to investigate the effect of different storage temperatures, low pressure storage,1-MCP, and the combined treatment of1-MCP and low pressure storage on postharvest physiology and storage life of Kuqa apricot. The mechanisms of Kuqa apricot fruit senescence and softening during storage were also studied in order to provide scientific basis for obtaining economically feasible preservation technology.(1) Kuqa apricot is a typical climacteric fruit, respiration rate and ethylene production showed a trend first and then decreased during storage. Storage temperature has a profound effect on Kuqa Apricot fruit quality. Cold storage inhibited the increase in respiration rate and ethylene production, reduced the loss of the fruit nutritional value (TSS, TA, Vc), retarded fruit decay, maintained fruit color, inhibited fruit LOX activity and the rise of H2O2content, reduced the degree of oxidation of membrane lipids and thereby suppressed the increase of the relative conductivity and MDA content. Thus low-temperature delayed senescence and extended storage life of Kuqa Apricot. Storage at0℃is more effective than10℃and25℃, indicating that the storage temperature plays an important role in maintaining fruit quality and is the key factor that must be considered in apricot fruit storage.(2) Better results were obtained from low pressure storage than ordinary storage at0℃. Low pressure storage at50kPa inhibited respiration intensity and maintained a low level of respiratory metabolism, thereby reducing the energy loss of fruit. This treatment inhibited the rise in ethylene production and immediately removed ethylene produced by the fruit to prevent its harmful effects to the fruit. Low pressure storage at50kPa also inhibited the increase in H2O2content and LOX activity rise, thus, reducing their toxic effects on the cell membrane and inhibiting the increase of MDA content and relative electrical conductivity, This treatment also inhibited the increase of cellulase, delayed the hydrolysis of pectin and cellulose material, therefore, reducing the damage to the cell wall and better able to maintain the cell structure and firmness of Kuqa apricot fruit. Low pressure storage at20or80kPa was also effective, but the results were not as good as those of50kPa. Taking into consideration of economic as well as equipment situation, Kuqa apricot fruit should be stored in50kPa.(3) Treatment with the combination of1-MCP (1μl/L) and50kPa at0℃not only inhibited the rise in fruit respiration rate and ethylene production, and reduced the consumption of respiratory substrate, but also maintained higher nutrients in fruit including TSSã€TA and Vc. This combination treatment was able to maintain the activities of SOD, APX, POD and CAT, inhibited LOX and PPO activities, in fruit, retarded the increase of O2-and H2O2in fruit, inhibited the accumulation of the relative conductivity and MDA content, and maintained the active oxygen metabolism balance. In addition, this combination treatment maintained better firmness of the fruit through the inhibition of PE, PG and cellulase activity rise, and the slowing of the degradation of pectic substances and cellulose as compared to the control.(4) In conclusion, the combination treatment with1-MCP (1μL/L)+low pressure storage at50kPa was more effective in delaying the senescence and softening of Kuqa apricot fruit than the treatment with1-MCP or low pressure storage alone. Our objective of delaying the softening and extending the storage life of Kuqa apricot fruit was achieved by using this combination treatment. |
