茉莉酸甲酯燻蒸對‘珍珠拔’番石榴果實採後寒害之影響

Effects of Methyl Jasmonate Fumigation on Chilling Injury of Harvested 'Jen-Ju Bar' Guava Fruit

‘珍珠拔’番石榴（Psidium guajava L.）為寒害敏感型園產品，果實貯藏在5℃以下便有發生寒害之虞，果實在低溫貯藏或低溫檢疫處理時，亟須建立減輕寒害之採後處理方法。本研究將‘珍珠拔’以0、25、50、100、200、2000 mg．L^(-1)之茉莉酸甲酯（methyl jasmonate, MJ）燻蒸處理16 h，結果顯示以100 mg．L^(-1)MJ可有效減緩在0℃貯藏7天與14天後於20℃回溫3天的寒害褐化面積，果皮葉綠素螢光值Fv／Fm分別為0.73和0.71，高於未燻蒸MJ之對照組的0.67和0.65，而果皮離子滲漏率分別為19%和21%也明顯較對照組30%和31%低；但是貯藏延長至21天即喪失減輕果皮寒害褐化之效果。100 mg．L^(-1)MJ燻蒸處理時間以16 h較6、12或24 h為佳。以100 mg．L^(-1)MJ處理16 h對‘珍珠拔’果實硬度、可溶性固形物、可滴定酸、抗壞血酸含量的品質變化並無不良之影響。 Jen-Ju Bar' guava fruit, a chilling-sensitive horticultural commodity, is susceptible to chilling injury (CI) when stored at 5℃ or lower temperatures. Establishment of postharvest method alleviating CI is crucial for lower temperature storage or cold quarantine. Effects of o, 25, 50, 100, 200, and 2000 mg．L^(-1) methyl jasmonate (MJ) CI of guava fruits were investigated. Results indicate that fumigation of 100 mg．L^(-1) MJ for 16 h exhibited the best efficacy in reducing peel browning area caused by CI of 'Jen-Ju Bar' fruits after storage for 7 and 14 days at 0℃ followed by 3 days at 20℃. As compared with the untreated control, the 100 mg．L^(-1) MJ treatment resulted in higher peel Fv/Fm values (0.71-0.73 vs. 0.65-0.67) and lower peel electrolyte leakage percentage (19%-21% vs. 30%-31%) on days 7 and 14 after storage. No alleviation effect of chilling injury was found between 100 mg．L^(-1) MJ and control when stored at 0℃ for 21 days. Fruits fumigated with 100 mg．L^(-1) MJ for 16 h had less CI than those for 6, 12, and 24 h. No negative side effect was observed in fruit quality attributes including firmness, total soluble solids, titratable acidity, and ascorbic acid.