中国农业科学 ›› 2008, Vol. 41 ›› Issue (5): 1317-1325 .doi: 10.3864/j.issn.0578-1752.2008.05.008

• 耕作栽培·生理生化 • 上一篇    下一篇

铜对苋菜幼苗光合参数和活性氧代谢的影响

柯世省   

  1. 台州学院生命科学学院
  • 收稿日期:2007-06-05 修回日期:2007-06-25 出版日期:2008-05-10 发布日期:2008-05-10

Effects of Different Copper Levels on Photosynthetic Parameters and Active Oxygen Metabolism of Amaranthus tricolor Seedlings

Shi-sheng KE   

  1. 台州学院生命科学学院
  • Received:2007-06-05 Revised:2007-06-25 Online:2008-05-10 Published:2008-05-10

摘要: 【目的】明确铜毒影响苋菜(Amaranthus tricolor)幼苗光合作用和活性氧代谢的生理机制。【方法】采用土培试验测定了不同水平铜处理下苋菜幼苗生长、光合作用、矿质元素吸收和活性氧代谢的相关指标。【结果】2.0~4.0 mmol•kg-1铜处理下植株干重降至无铜处理(对照)的91%~73%,净光合速率和气孔导度均明显减小,但胞间CO2浓度并没发生显著变化,最大光化学效率的变化比实际量子效率小得多,这暗示着光合作用暗反应对ATP和NADH需求减少使光化学下调。此外,叶片光合色素、水分和矿质元素Fe、K和Mg含量均明显降低,Cu含量明显升高。2.0~4.0 mmol•kg-1铜处理显著增加叶片超氧化物歧化酶、过氧化物酶活性和脯氨酸含量,降低过氧化氢酶、抗坏血酸过氧化物酶活性及类胡萝卜素、还原型谷胱甘肽和抗坏血酸含量,并伴随丙二醛含量和细胞电解质渗漏率增加。【结论】2.0 mmol•kg-1以上铜处理引起苋菜活性氧代谢失衡,明显降低净光合速率和实际量子效率,加剧过氧化作用,导致植株生长严重受阻。

关键词: 苋菜, 铜毒, 光合作用, 活性氧代谢

Abstract: 【Objective】The objective of this study was to gain better insight into the physiological mechanisms of copper (Cu) on photosynthesis and active oxygen metabolism in three-coloured amaranth plants (Amaranthus tricolor). 【Method】The experiments were performed to investigate the parameters of growth, photosynthesis, mineral elements contents and active oxygen metabolism. Three-coloured amaranth seedlings were subjected to different Cu levels in soil at the whole experimental period. 【Result】2.0-4.0 mmol•kg-1 Cu treatment decreased the whole plant dry mass to 90%-73%. The net photosynthetic rate (Pn) and stomalal conductance (gs) in the third leaves of three-coloured amaranth seedlings treated with 2.0-4.0 mmol•kg-1 Cu were similarly reduced. None of the investigated Cu levels decreased internal CO2 concentration (Ci). The effect of Cu on potential efficiency of photosystem Ⅱ, PSⅡ (Fv/Fm) was negligible. The Cu dependent reduction of PSⅡ quantum efficiency (ΦPSⅡ) after plant adaptation in actinic irradiation was more noticeable. This could imply that reduced demand for ATP and NADPH in a dark phase of photosynthesis caused a down-regulation of PSⅡ photochemistry. Furthermore, in third leaves of Cu-treated plants the decrease in water percentage as well as lower contents of photosynthetic pigments and mineral elements including Fe, K and Mg were observed. Superoxide dismutase (SOD) and guaiacol peroxidase (POD) activities and proline (Pro) content in third leaves of three-coloured amaranth seedlings treated with 2.0-4.0 mmol•kg-1 Cu significantly increased, while catalase (CAT) and ascorbate peroxidase (APX) activities and the contents of carotenoid (Car), glutathione (GSH) and ascorbic acid (AsA) decreased accompanied by the contents of hydrogen peroxide (H2O2), superoxide (O2-•) and malondialdehyde (MDA) and electrolyte leakage increased. 【Conclusion】 Treated with 2.0-4.0 mmol•kg-1 Cu, Pn and ΦPSⅡ decreased, and peroxidization aggravated by unbalance of active oxygen metabolism, so the growth of three-coloured amaranth were significantly inhibited.

Key words: Copper toxicity, Growth, Photosynthesis, Active oxygen metabolism, Three-coloured amaranth plants (Amaranthus tricolor)