Inhibitory effect of oxalic acid soaking treatment on Penicillium digitatum infection in postharvest navel oranges
To investigate the relationship between the induction effect of exogenous oxalic acid(OA)on the resistance to postharvest green mold and antioxidant capacity of navel orange fruits,and screen the appropriate concentration of exogenous OA treatment,Longhuihong navel orange fruits were used as the experimental ma-terials and soaked with 0(water treatment as control),12.5,25.0 and 50.0 mmol·L-1 OA for 10 min,and inducing the resistance at 25℃ for 48 h,then the spore suspension of Penicillium digitatum was inoculated by pinprick of the fruits.The optimum concentration of exogenous OA treatment was screened by analyzing the diameter of lesions.The total content of phenols and flavonoids,antioxidant enzymes activities and malon-aldehyde(MDA)content in flavedo and their dynamic changes in fruits treated with the optimum OA concen-tration and inoculated with spore suspension were determined.The results showed that the induction effect of 12.5,25.0 and 50.0 mmol·L-1 OA treatments on the resistance of navel orange to green mold were 16.26%,25.22%and 17.36%,respectively.The induction effect of 25.0 mmol·L-1 OA treatment was significantly higher than that of the other two treatments.25.0 mmol·L-1 OA treatment significantly increased the activities of ascorbate peroxidase(APX),peroxidase(POD)and polyphenol oxidase(PPO),promoted the accumulation of total phenols and flavonoids,improved the ability of free radical scavenging,inhibited the accumulation of MDA in flavedo,then reduced the occurrence of green mold of navel orange.25.0 mmol·L-1 OA treatment increased the resistance of navel orange to postharvest green mold,which may be closely related to the increase of antioxidant capacity of navel orange induced by OA.
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维普
