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采用4个不同pH值(pH7,6,5,4)培养液模拟菜豆萌发和幼苗生长环境,研究了酸化条件下菜豆种子萌发和幼苗生长特性、幼苗根系和幼叶的抗氧化酶系活性以及叶片的碳氮代谢的主要酶系活性和产物水平,以期明确菜豆的碳氮代谢对酸化胁迫的响应机制。结果表明:随着pH的降低,菜豆发芽势和发芽率降低,幼苗和根系干物质量减少;谷氨酰胺合成酶活性降低,蔗糖磷酸合成酶活性增强,从而增加了蔗糖、果糖和总可溶性糖含量;根系的超氧阴离子自由基(O2ˉ·)和丙二醛(MDA)含量降低,叶片的O2ˉ·和MDA含量增加,而叶片和根系的抗氧化酶系活性同向变化,即超氧化物歧化酶和过氧化氢酶活性增强,过氧化物酶活性降低。酸化条件下,菜豆的碳代谢加强,氮代谢受到抑制;叶片过氧化物酶活性的降低和O2ˉ·含量的增加,导致了叶片膜脂过氧化程度的加剧。
Four different pH values (pH7, 6, 5 and 4) were used to simulate the germination and seedling growth environment of bean and to study the seed germination and seedling growth characteristics under acidified conditions, the antioxidant enzyme activities of seedling root and young leaves, The main enzyme activities and product levels of leaf carbon and nitrogen metabolism were determined in order to clarify the response mechanism of carbon and nitrogen metabolism of bean to acidification stress. The results showed that with the decrease of pH, the germination potential and germination rate of bean decreased, the amount of dry matter in seedling and root decreased, the activity of glutamine synthetase decreased and the activity of sucrose phosphate synthase increased, which increased the content of sucrose, fructose and total soluble sugar (O2ˉ ·) and malondialdehyde (MDA) contents in roots decreased, while the contents of O2ˉ · and MDA in leaves increased, while the activities of antioxidant enzymes in leaves and roots changed in the same direction, that is, superoxide dismutase Enzyme and catalase activity increased, peroxidase activity decreased. Under acidification conditions, the carbon metabolism of kidney bean was enhanced, and the nitrogen metabolism was inhibited. The decrease of peroxidase activity and the increase of O2ˉ · content led to the aggravation of membrane lipid peroxidation.