Effects Of Cortex Magnolia Officinalis Extract On Postharvest Storage Characteristics And Quality Of Peach Fruit

In this paper, control of postharvest diseases of peach fruit ( "Bayuecui") by postharvest infiltration inoculation or dipping of Cortex Magnolia Officinalis extract was investigated, and effects of these treatments on storage characteristics, quality and physiological metabolisms, disease resistance of peaches were also evaluated during storage at 0±0.5℃. Mechanisms of these treatments involved in enhancement of fruit resistance against postharvest diseases and improvement of fruit quality were studied. Results from our studies will provide theoretical information on how to effectively reduce postharvest decay and improve quality of peach fruit, and provide alternatives to applications of chemical fungicides on fruit and vegetable. The primary results of this research were as follows:Firstly, The results of postharvest Cortex Magnolia Officinalis extract treatment in peach fruit showed that 3.13mg/mL, 6.25mg/mL and 12.50mg/mL treatment showed the significantly inhibitory effects in natural fruit decay and inoculated diseases of Monilinia.fracticola and Rhizopus stolonifer rot in peach fruit. Cortex Magnolia Officinalis extract treatment reduced respiration rate of peach, inhibited decreases of fruit firmness and TSS level, reduced the sarcocarp browning degree of peach fruit while had little effect on TA content of fruit. Among three concentrations of Cortex Magnolia Officinalis extract, 6.25mg/mL was the best one to peach fruit postharvest treatment. In the sixth week of storage, after by 6.25mg/mL Cortex Magnolia Officinalis extract treatment, the respiration rate of peach fruit reduced 33.45% less than CK(blank water treatment), the fruit firmness and the TSS content increased respectively 14.81% and 8.57% more than CK.Secondly, 6.25mg/mL Cortex Magnolia Officinalis extract treatment effectively enhanced the activities of defense enzymes including phenylalanine ammonia-lyase (PAL), chitinase (CHT) and β-1,3-glucanase (GLU), and inhibited the activities of peroxidase (POD) and polyphenoloxidase (PPO)of peach fruit during storage. In the sixth week of storage, the PAL, CHT and GLU activity of peach fruit treated with 6.25mg/mL Cortex Magnolia Officinalis extract raised respectively 141.23%, 23.42% and 48.07% more than CK; and the activities of POD and PPO reduced respectively 16.02% and 26.27% compared with CK.Thirdly, In the condition of peach fruit decay incidence at room temperature less than 5%, the peach fruit treated with 6.25mg/mL Cortex Magnolia Officinalis extract had 4 days shelf life after cold storage(0±0.5℃) of 10 weeks.Fourthly, the possible mechanisms of Cortex Magnolia Officinalis extract treatments involved in enhancement of fruit resistance against postharvest diseases and improvement of fruit quality were as follows: (1) Cortex Magnolia Officinalis extract delayed the senescence of peach fruit after harvest and retained the fruits' strong disease resistance against pathogenic germs. (2) Cortex Magnolia Officinalis extract promoted the phenylallyl alkyl metabolizability of the peach fruit and improved the content of germ-proof substance in fruit. (3) Cortex Magnolia Officinalis extract induced the synthesization of Pathogenesis Related Proteins( PRs) in peach fruit and enhanced the disease resistance of peach fruit.