次適溫對萌爆處理後苦瓜種子抗氧化作用之影響

Abstract

中 文 摘 要 苦瓜屬於熱帶作物，其種皮較為堅硬，在次適溫下普遍有出土率低落及出土時間過長的問題。本研究以特6號及月華兩種苦瓜品種為材料，利用固體萌爆(SP)、溫湯處理(WWS)及WWS+SP處理後，探討在適溫(25℃)、次適溫(20℃)及低溫(15℃)下，苦瓜種子出土率改善之可能生理因素。試驗結果顯示，次適溫確會降低苦瓜種子出土率及增加出土時間，並且苦瓜種子之堅硬種皮會干擾水分與氧氣的吸收，亦為造成其發芽出土弱勢的原因，而萌爆及溫湯處理則確實能改善此一問題。經處理後的種子，其種臍抗穿刺阻力較未處理的種子為小。種子的電解質滲漏量測定也顯示，萌爆及溫湯處理能使膜系獲得修補，改善種子活力。試驗結果也顯示經萌爆處理後，確實可以有效地提高過氧化物清除機制活性，降低苦瓜種子內脂質過氧化物的累積，進而改善幼苗出土率及生長勢。經不同處理後之苦瓜種子在適溫與次適溫下之出土率測試有顯著的促進效果。在三種不同種子處理方法中，以固體萌爆處理與溫湯處理+固體萌爆處理最能有效提昇種子活力，改善種子在次適溫下之出土，而溫湯處理+固體萌爆處理方式較為複雜，建議以具有相同效果的固體萌爆處理方法來處理苦瓜種子，解決其在次適溫下之出土問題。

Abstract Bitter gourd is a tropical crop accompanying with hard seed coat. It is generally lower in emergence percentage and longer in emergence time. In this study, seeds of two bitter gourd cultivars Special Six and Moon Shine were subjected to different presowing treatments (solid priming, warm water soaking and a combination of solid priming and warm water soaking). For evaluating the possible physiological traits related to emergence percentage of seeds, both treated and non-treated seeds were germinated under 25 ℃(normal temperature), 20 ℃(sub-optimal temperature) and 15 ℃(low temperature). The results indicated that sub-optimal temperature lowered the emergence percentage and delayed emergence time of bitter gourd seeds. The hard seed coat of bitter gourd seed might affect the emergence by interrupting the absorption of water and oxygen. However, priming or warm water soaking the seeds alleviated these problem to some extend. The puncture resistances of hilum of the treated seeds were lower than the non-treated seeds. Imbibitional leakage test confirmed the benefit of treatments on the membrane repairing and subsequent seed vigor. The data further indicated that these presowing treatments could reduce the accumulation of peroxides by enhancing the activities of peroxide-scavenging enzymes, and subsequently improve seedling vigor at sub-optimal temperature. Among these three treatments, treatments solid priming and solid priming＋warm water saoking were more effective in improving the seed vigor. However, the treatment solid priming＋warm water saoking is more complex than SP, therefore, treatment SP is a better way to improve the emergence percentage of bitter gourd seeds under sub-optimal temperature.