Aging Physiology of Peanut Seed

本研究主要目的為利用人工老化方式，探討花生種子台南11號及立枝仔之 老化生理因素，並以萌爆技術來處理高活力及低活力種子花生種子，以探 討種子活力改善之可能生理因素。試驗結果顯示，人工老化種子之發芽率 ﹑發芽速度﹑發芽係數﹑幼苗長度及幼苗乾重均明顯下降，全粒種子及切 離胚軸之滲漏均隨人工老化處理增加，顯示人工老化處理已造成種子膜系 破壞，因而造成種子之生理代謝異常，因此種子之呼吸作用率及異檸檬酸 分解﹑蘋果酸合成合成均隨人工老化處理明顯下降。本研究也同時測 試脂氧化﹑超氧歧化﹑觸﹑過氧化及ascorbate peroxidase等酵 素在人工老化期間之活性變化，以了解膜系破壞的因素，結果發現除觸 及子葉內脂氧化type-I之活性外，其他各種酵素活性均隨人工老化處理 而下降，所以由脂氧化來促進脂質過氧化而造成種子老化的可能性似乎 不高，但自由基及過氧化物清除酵素活性降低，造成過氧化物及MDA的累 積，這些現象可能與老化現象有關。萌爆處理可明顯提高種子活力，此一 現象可能與種子胚軸內超氧歧化﹑觸﹑過氧化﹑ascorbate peroxidase及種子子葉內觸﹑ascorbate peroxidase等之活性，因萌爆 處理而提升有關。The basic objective of this study was to iden- tify the factors linked to accelerated seed aging in "TN.11" and "Li-Chih Tzae" peanut cultivars. The effect of solid matric priming on high vigor and low vigor peanut seeds were investigated. The results indicated that accelerated aging reduced seed vigor parameters including germination time ,germination coefficient ,seedling length and seedling dry weight. Increasing leakage in seed and axes coincided with the vigor decline,indica- ting the loss of membrane integrity through acce- lerated aging ,Moreover , sereral metabolic acti- vities seed became abberrant , with lower respi- tion and reduced isocitrate lyase and malate synthase activities were obtained in aged seeds. In this study , we aslo evaluated the activities of lipoxygenase ,superoxide dismutase ,catalase ,peroxidase and ascorbate peroxidase in peanut seeds . subjected to diffenrent aging duration in two cultivars. It appeared that most of enzyme lost their activity at accelerated aging except that the activity of cotyledon- catalase and the activity pf cotyledon-lipoxygenase type-II remaining unchanged during accelerated aging. These results seem to indicate that the decresed lipoxygenase activity was unlikely to be the factor including lipid peroxidation . Importantly ,the reduced activities of the scavening enzymes of free radical and peroxide were responsible for the stimulated lipid peroxidation observed in aged peanut seeds . Solid matric priming improved the vigor of peanut seed.This phenomenon might be linked to the increased superoxide dismutase, catalase, peroxidase, and ascorbate activities