茉莉酸酮類貯前處理技術對減輕‘珍珠拔’番石榴寒害
效果與其可能機制之探討

‘珍珠拔’番石榴(Psidium guajava L.)為臺灣重要經濟果樹之主要栽培品種。為拓展外銷市場，目前模擬檢疫條件(0℃貯藏14天)或長期運輸都會將番石榴果實置於低溫環境，但由於番石榴屬於低溫敏感型園產品，容易在採後處理過程遭受寒害，呈現外觀褐變、凹陷徵狀而喪失商品價值。雖然‘ 珍珠拔’貯藏前以茉莉酸甲酯(methyl jasmonate，MeJA)燻蒸可延緩及減輕寒害徵狀發生，但是燻蒸處理耗時(16小時)、需要密閉空間都減損實際運用的可行性。本試驗目的在開發MeJA與茉莉酸(jasmonic acid，JA) 減壓及浸泡處理減輕‘ 珍珠拔’減輕寒害的處理條件，以縮短採後處理時間，維持果品品質。‘珍珠拔’果實浸泡於0.1 mM JA或MeJA溶液分別進行400、500、600、650、700mmHg減壓處理1或5分鐘，所有減壓處理組皆較對照組寒害嚴重。 ‘珍珠拔’果實以0.05~1 mM MeJA或0.05~0.2 mM JA浸泡不同時間處理，經0℃貯藏14天、20℃回溫3天，以外觀寒害指數、果皮離子滲漏率、光合系統II最大光化學量子效率(maxium quantum efficiency of PSII photochemistry；Fv / Fm)評估果實寒害程度，結果顯示本試驗所使用的MeJA處理條件皆無法有效減輕寒害發生。然而，0.1 mM JA浸泡10 mins處理寒害指數為2.5較對照組3.5減輕番石榴寒害發生，其離子滲漏率約42%較對照組55%低，並且於低溫貯藏期間較能減緩Fv / Fm值下降約0.7，果實寒害徵狀較其他處理組輕微；探討0.1 mM JA浸泡處理10 min減輕‘珍珠拔’番石榴寒害機制，總抗氧化能力部分DPPH自由基清除能力在貯藏後期上升，FCR值顯著高於對照組，貯藏期間延緩catalase活性下降， superoxide dismutase 、glutathione redutase酵素活性及比活性皆在貯藏第14天及回溫後高於對照組，增加還原態AsA含量，推測JA減輕番石榴寒害的機制可能與提高其抗氧化系統，清除ROS能力增加，減少細胞產生氧化逆境。

關鍵字

茉莉酸；寒害；抗氧化系統

並列摘要

‘Jen-Ju Bar’guava (Psidium guajava L.) is an important economical fruit crop in Taiwan. In order to expand the overseas market, both quarantine treatment (14 days at 0℃) and long-term transportation have been associated with low temperature storage for guava fruits. However, since guava fruit is a chilling-sensitive produce, low temperature storage often causes chilling injury (CI) symptoms, such as browning and pitting, on guava fruits, reducing the quality and marketability. To reduce the development of CI symptoms, methyl jasmonate (MeJA) has been utilized in the form of fumigation. But the fumigation treatment of MeJA demands an airtight space and long period of time (16 hours), which is time-consuming and hence decreasing the practicability of this method. Therefore, the objective of this study is to develop an effective treatment to reduce the CI by using MeJA and jasmonic acid (JA) for both immersion and pressure infiltration. For immersion treatment, fruits were first dipped in solution of 0.05~1 mM MeJA and 0.05~0.2 mM JA , and then stored at 0℃ for 14 days followed by 3 days at 20℃. CI index, electrolyte leakage and maximum quantum efficiency of PSII photochemistry (Fv / Fm) were used to estimate the level of CI. Result showed that, the CI index of treatment with 0.1 mM JA for 10 minutes was 2.5, which is significantly lower than that of control group, 3.5. And the percentage of electrolyte leakage of treated group is 42%, while that of control group is 55%. Furthermore, JA treatment delayed the decrease in the Fv / Fm value guava fruits. In contrast, the treatment of 0.05~1 mM MeJA showed no effect on CI development. For pressure infiltration treatment, fruit were pressure infiltrated at 400、500、600、650、700 mmHg for 1 or 5 min in 0.1 mM JA or MeJA solution. However, comparing with control fruits, all fruits showed serious CI symptoms after pressure infiltration treatment. To study the mechanism of JA on reducing the CI of guava fruits, the enzyme activity of catalase, superoxide dismutase, and glutathione reductase were analyzed. Results showed that the activity of catalase decreased during storage, while the activity of superoxide dismutase, glutathione reductase, and AsA in treated fruits were significantly higher than control group at the 14th day of storage and under 20℃. And the DPPH percentage of treated fruits increased during the later stage of storage. It could be inferred that JA alleviate CI symptoms on guava fruits possibly via increasing the antioxidant system and the ability of scavenging reactive oxygen species (ROS) therefore reducing the oxidative stress.

並列關鍵字

jasmonic acid ； chilling injury ； antioxidant system

參考文獻

張哲嘉、林宗賢. 1998. 臺灣番石榴生產之現況與改進. 中國園藝 44:116-124.

郭婉秋、柯立祥. 2006. 貯藏前熱水處理對‘珍珠拔’和‘水晶拔’番石榴果實採收後生理、品質及貯藏壽命之影響. 臺灣園藝 52:413-431.

楊淑惠、謝鴻業. 2004. 具有亞硝酸鹽清除力的水果-番石榴. 農業試驗所技術服務58:21.

劉德駿. 2010. 不同後熟特性番石榴品種ACC氧化酶cDNA之選殖與分析. 國立臺灣大學園藝學系碩士論文. 臺北.

謝鴻業. 2002. 栽培番石榴應有的正確觀念. 高雄區農業專訊40:24-26.

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茉莉酸酮類貯前處理技術對減輕‘珍珠拔’番石榴寒害效果與其可能機制之探討

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