镉污染对水稻不同生育期抗氧化系统的影响

Antioxidative responses to cadmium stress in the leaves of Oryza saliva L. in different growth period

采用土培的方法,研究了不同Cd添加水平(0、5、10、20、30、60 mg.kg-1,以CK,T1,T2,T3,T4,T5表示)对水稻分蘖期、孕穗期和抽穗期叶绿素、可溶性蛋白质、丙二醛(MDA)、总巯基(-SH)、谷胱甘肽(GSH)、植物络合素(PCs)含量以及水稻叶片中超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性的影响。结果表明,叶片中Cd的含量随生长时期的延长而增加;T1处理时,水稻3个时期中叶绿素a、叶绿素b、叶绿素a+b含量最高,表明低质量分数Cd有利于水稻的生长;而T4和T5处理显著降低了叶绿素含量(P<0.05)。Cd对不同生育时期抗氧化酶的影响不一,对分蘖期SOD、POD、CAT活性影响较明显,而对孕穗期和抽穗期SOD、POD、CAT活性以及可溶性蛋白质含量影响不显著(P>0.05)。高质量分数Cd提高了叶片中MDA含量,在T5处理时,MDA含量在分蘖期、孕穗期和抽穗期分别为对照的1.9倍、4.5倍和4.6倍。水稻不同生育时期总-SH、GSH、PCs含量随着Cd处理质量分数的增加而增加,表明Cd处理诱导了水稻PCs的解毒机制。

Effects of cadmium （Cd） on various enzymatic antioxidants and non-enzymatic antioxidants in the leaves of Oryza saliva L. in different growth period （the tillering stage, the booting stage and the heading stage） were studied. Rice seedling was grown in soils added with various Cd concentrations （0, 5, 10, 20, 30, 60 mg.kgl）. Plant leaves were analyzed for contents of glutathione （GSH）, phytochelatins （PCs） and total acid soluble SH, chlorophyll, malondialdehyde （MDA） and activities of superoxide dismutase （SOD）, peroxidase （POD） and catalase （CAT）. Results showed that the contents of chlorophyll a, chlorophyll b and chlorophyll a＋b were the highest with the 5 mg.kglCd concentration in the soil. The content of Cd and MDA in the leaves increased as the soil Cd concentrations rose. Under the stress of Cd, the activities of SOD, POD and CAT in rice＇s leaves in different growth period showed their maximums in the tillering stage, and the minumums appeared in the heading stage. The contents of GSH, PCs and SH rose with the increment of Cd treatment concentrations. The results indicated both enzymatic and non-enzymatic antioxidants played significant roles in Cd detoxification in this plant different growth period.