中文摘要：

以4年生南方红豆杉幼苗为实验材料,通过对南方红豆杉幼苗喷施不同浓度外源一氧化氮（NO）供体硝普钠溶液（0、0.01、0.1、0.5和1 mmol·L-1SNP）,测定光合色素含量、抗氧化酶活性、丙二醛（MDA）含量和过氧化氢（H2O2）含量等生理指标,以探讨不同浓度外源NO对南方红豆杉叶片光合色素和抗氧化酶的影响。结果表明：喷施低浓度（0.01、0.1mmol·L-1）SNP可显著提高南方红豆杉叶片的叶绿素a、叶绿素b、类胡萝卜素和总叶绿素含量,增加叶绿素a/b的比值,而喷施高浓度（0.5、1 mmol·L-1）SNP降低了叶片的光合色素含量。随着外源NO供体浓度的增加,叶片过氧化氢酶（CAT）活性显著增加,过氧化物酶（POD）活性先增加后降低。此外,处理前期,低浓度SNP处理明显提高了抗坏血酸过氧化物酶（APX）活性,而高浓度SNP处理显著降低了APX活性,处理后期APX活性随SNP浓度的增加而显著下降。喷施低浓度SNP可有效提高超氧化物歧化酶（SOD）活性和增加可溶性蛋白含量,降低MDA和H2O2的含量,而喷施高浓度SNP显著增加了MDA和H2O2的含量。因此,低浓度的SNP（〈0.5 mmol·L-1）处理南方红豆杉幼苗,可增加其叶绿素含量,提高抗氧化酶活性,降低MDA和H2O2的含量,而高浓度的SNP（≥0.5 mmol·L-1）处理会降低叶绿素含量,提高H2O2含量,增加细胞膜质过氧化程度,从而对南方红豆杉幼苗造成一定伤害。

英文摘要：

In this experiment,4-year-old Taxus chinensis var.mairei seedlings were used as test material and treated with different concentrations（0,0.01,0.1,0.5 and 1 mmol·L-1） of sodium nitroprusside（SNP）,a donor for exogenous nitric oxide（NO） to study the effect of exogenous nitric oxide on photosynthetic pigment and antioxidant enzymes in T.chinensis seedlings.The contents of photosynthetic pigment,malondialdehyde（MDA） and hydrogen peroxide（H2O2）,and the activities of antioxidant enzymes in T.chinensis seedlings were determined.Spraying low concentrations（0.01,0.1 mmol·L-1） of SNP would significantly increased chlorophyll a/b ratio and the contents of chlorophyll a,chlorophyll b,carotenoids and the total chlorophyll,while the treatment of high concentrations（0.5,1 mmol·L-1） of SNP would reduce the chlorophyll contents.The activity of catalase（CAT） significantly increased with the increasing of the concentration of exogenous NO donor,while the activity of peroxidase（POD） was first increased,and then decreased.Moreover,at the early stage of treatment,low concentrations of SNP treatment obviously increased the ascorbate peroxide（APX） activity,while high concentrations of SNP treatment significantly decreased the APX activity,and at the later stage of treatment,the activity of APX significantly decreased with the increasing of SNP concentration.Spraying low concentrations of SNP would effectively improve the superoxide dismutase（SOD） activity and increase the soluble protein concentrations,reduced MDA and H2O2 contents,while the treatment of high concentrations of SNP significantly increase the MDA and H2O2 contents.Therefore,treatment of low concentrations of SNP（0.5 mmol·L-1） would increase chlorophyll contents,the activity of antioxidant enzymes,and reduce the MDA and H2O2 contents in T.chinensis seedlings,while the treatment of high concentrations of SNP（≥0.5 mmol·L-1） would reduce the chlorophyll contents,increase the H2O2 contents and membrane lipid peroxidati