次適溫對萌爆處理後苦瓜種子活勢之影響

Abstract

苦瓜種子在次適溫下普遍有出土率低落及出土時間過長的問 題。本試驗以特6號及月華二品種苦瓜種子為材料，利用固體萌爆 (SP)、液體熱萌爆(LP)及LP+SP處理後，在適溫（25℃）、次適溫(20 ℃)及低溫（15℃）下進行出土率的調查。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，而萌爆處理亦確實能改善此 一問題。電解質滲漏量的測定也顯示，萌爆處理能改善種子活力。利 用掃描式電子顯微鏡觀看種皮後，發現經過萌爆處理的種子，種皮細 胞結構較未處理的種子鬆散，在X-ray的觀測下，經萌爆處理後種子 內的空腔也較小。此外，在適溫、次適溫及低溫下種子萌芽時所誘導之異檸 檬酸裂解梅、蘋果酸合成梅及蘋果酸去氫梅的活性也因萌爆而明顯提 升。整體而言在此三種萌爆處理方式中，以LP+SP處理最能有效地提 升苦瓜種子活力，改善種子在次適溫出土問題及品質。

Bitter gourd seeds are generally lower in emergence percentage and longer in emergence time. In this study, seeds of two bitter gourd varieties (Special Six and Moon Shine)were subjected to different priming treatments(solid priming (SP), liquid thermo-priming (LP) and a combination of solid and liquid-thermo priming (LP＋SP)).Both primed and non-primed seeds were emerged under norm temperatures(25℃) sub-optimal temperatures( 20℃)and low temperatures(15℃). The results indicated that sub-optimal temperatures lowered the emergence percentage and increased emergence time of bitter gourd seeds. However, priming alleviated this problem to some extend. Electrolyte leakage test confirmed the benefit of priming on seed vigor. Scanning electron microscope examination revealed a loose structure of seed coat in comparison with non-primed controls. X-ray examination also revealed that primed seeds tended to have a smaller unfilled free space compared to that of controls. In addition, priming also increased the activities of isocitrate lyase, malate synthase and malate dehydrogenase during seedling emergence under sub-optimal temperature. Among the three priming treatments, liquid thermo-priming plus solid priming was the best method to overcome the poor sub-optimal emergence of bitter gourd seeds.