種子萌爆處理後對超甜玉米幼苗鞘葉及葉片延長之研究

Abstract

種子經萌爆後，均有發芽時間及幼苗出土時間縮短之現象，且具有幼苗生長優勢，但幼苗出土時間縮短與幼苗生長優勢，究竟是肇因與發芽時間提前，或細胞生長加速，則仍無定論。本試驗係以超甜玉米（Zea mays L.）Honey236（H236）為試驗材料，研究種子萌爆處理後，幼苗芽鞘（coleoptile）及葉片延長速率，細胞壁內過氧化活性與過氧化氫含量之變化情形。研究結果顯示，在取樣期間，對照組與萌爆處理組地上部（芽鞘 + 葉片）之鮮重、乾重及水分含量，均有逐漸增加之趨勢。唯在水分含量上，以萌爆處理組之幼苗所發生之變化較大。二種處理在芽鞘延長速率上無明顯差異。但在幼苗葉片生長上，二種處裡有顯著差異，以萌爆處理組之葉片延長速率較高。在芽鞘及葉片中過氧化氫含量變化，對照組含量明顯高於萌爆處理組。經處理芽鞘及葉片內鍵結在細胞壁上之過氧化（ionically bound peroxidase、covalently bound peroxidase及ferulic acid-peroxidase）及NADH-peroxidase（NADH-POD）和diamine oxidase（DAO）活性萌爆處理均高於其對應之對照組。

Priming is known to shorten the germination speed, emergence speed and to improve seedling vigor. Whether the shortened emergence speed and improved seedling vigor are due to the faster germination or increased cell growth is still not defined. In the present study, seeds of sweet corn cultivar Honey 236 was primed and the relationships among the elongation of coleoptile and leaves, the activities of peroxidases and the levels of H2O2 were exanined. The results indicated that the fresh weights, dry weights and moisture level of coleoptiles + leaves were increased during sampling period. Primed samples had higher moisture level than non-primed samples. No difference in coleoptile elongation rates was observed between primed and non-primed samples. However, evident difference in leaf elongation rate existed between two treatments, with the primed samples having higher growth rate than non-primed samples. Non-primed sample accumulated more H2O2 in growing coleoptile and leaves, and had lower ionically bound peroxidase, covalently bound peroxidase, ferulic acid-peroxidase, NADH-peroxidase and Diamine oxidase (DAO)than primed counterparts.