鎘對綠豆生長及生理之影響

Abstract

綠豆幼苗經鎘處理後，乾物重、含水量及葉片總葉綠素濃度減少，葉黃素之合成亦受到影響。植株產生矮化現象、葉片縮小、嫩葉黃化易脫落，根部生長亦受限制，根群小且褐化。 經鎘處理之綠豆幼苗，根部累積大量之鎘。地上部氮、鉀、鈣、鎂、鐵及錳濃度減少，而磷及鋅在低濃度鎘處理時增加。顯示鎘處理可影響元素之吸收及運送。 綠豆幼苗經鎘處理後，葉片及根部硝酸鹽濃度減少，氨濃度及可溶性碳水化合物濃度增加。葉片可溶性蛋白質亦有增加現象，根部總游離胺基酸濃度減少。葉片及根部硝酸鹽還原酶活性降低，而酸性磷酸酯酶、過氧化物酶及α-澱粉水解酶活性增加。過氧化物酶及水解酵素活性之提高，顯示鎘有促進綠豆幼苗衰老之現象。The objectives of this experiment was to investigate the effects of cadmium on the growth and metabolism of the mungbean seedlings. The dry weight, water content and total chlorophyll concentration of seedlings were found decreased. Chlorosis, abscission of upper leaves, browning of roots and reduced growth rate occurred in seedlings treated with cadmium. Besides, the synthesis of xanthophylls were also affected. Cadmium was accumulated in the roots of mungbean seedlings after treatment. The aboveground parts showed a decrease in concentration of nitrogen, potassium, magnesium, calcium, iron and manganese and an increase in phosphorus and zinc. Also a decrease in concentration of nitrogen, phosphorus, potassium and manganese and an increase in calcium, zinc, copper and iron were observed in roots. This seems to indicate that absorption and translocation of some elements were hampered by cadmium. The total free amino acids in root, nitrate in both leaves and roots decreased while soluble protein in the root, ammonia and soluble carbohydrate in leaves and roots were increased after treatment. The total free amino acids in leaves, soluble protein in roots were not effected by cadmium. The activities of acid phosphatase, α-amylase and peroxidase were enhanced whereas that of nitrate reductase was reduced by cadmium. The increase in hydrolytic enzymes and peroxidase activities could be a sign of senescense brought about by cadmium treatment