镉胁迫下施氮措施对喀斯特特有树种蚬木生理生化的影响

摘要

采用盆栽方法,研究镉胁迫及施氮措施对喀斯特特有树种蚬木(Excentrodendronhsienmu)抗性生理特性的影响,结果表明:镉胁迫显著降低了蚬木可溶性糖、可溶性蛋白和叶绿素含量(P<0.05),高镉胁迫(120 mg/kg)时,分别比对照(CK)降低19.0%、12.0%和33.3%;镉胁迫显著提高蚬木丙二醛(MDA)、脯氨酸(Pro)含量以及超氧化物歧化酶(SOD)活性(P<0.05),高镉胁迫时,分别比CK升高65.3%、72.9%和12.1%.低镉胁迫(30 mg/kg)下施氮,蚬木叶绿素、可溶性蛋白含量以及超氧化物歧化酶SOD活性均在低氮(0.4 g/kg)处理时达到最高,分别比不施氮处理升高8.6%、8.8%和4.1%,同时丙二醛含量也达到最低,比不施氮处理降低19.9%,以上除叶绿素外,其它指标均与不施氮处理存在显著差异(P<0.05);蚬木叶片脯氨酸随着施氮量的增加而降低,可溶性糖含量则表现不断上升趋势,高氮(0.8 g/kg)处理时,脯氨酸比不施氮处理显著降低9.2%,可溶性糖则升高51.5%,但低氮与高氮之间均无显著差异.高镉(120 mg/kg)胁迫下施氮,蚬木叶绿素含量、可溶性蛋白含量、脯氨酸含量均随着施氮量的增加而不断降低,并且高氮处理分别比不施氮处理显著降低19.3%、25.0%和38.2%;施氮均显著降低超氧化物歧化酶活性、提升可溶性糖含量,而对丙二醛无显著影响.镉胁迫下施氮,蚬木主要通过增加体内可溶性糖含量来更好的适应镉胁迫环境.低镉胁迫下施低氮对蚬木镉胁迫环境的适应性有一定的提升作用,而高镉下施氮以及低镉下施高氮均使氮协同镉对蚬木产生毒害作用.%The effect of nitrogen application on resistance of endemic species Excentrodendron hsienmu under cadmium stress in Karst areas was studied by using pot-culture method.Results indicated that contents of solu-ble sugar,soluble protein and chlorophyll significantly reduced under cadmium stress,which reduced by 19.0%,12.0% and 33.3%,respectively under high cadmium stress(120 mg/kg).The content of MDA,pro-line(Pro)and superoxide dismutase(SOD)activity significantly increased,which increased by 65.3%, 72.9% and 12.1%,respectively under high cadmium stress.Under low cadmium stress(30 mg/kg),com-pared with control group,the chlorophyll content,soluble protein content and SOD activity reached the high-est in the treatment of low nitrogen(0.4 g/kg),which increased by 8.6%,8.8%,4.1%,respectively,and MDA content reached the lowest,which reduced by 19.9%,and all indexes existed significant differences in addition to chlorophyll(P<0.05).The Pro decreased with the increase of nitrogen application,but soluble sugar content increased.Pro reduced by 9.2% and soluble sugar content increased by 51.5% with the high nitro-gen treatment(0.8 g/kg),but there was no significant difference between low nitrogen and high nitrogen.The content of chlorophyll and soluble protein as well as Pro decreased with the increase of nitrogen application un-der high cadmium stress.The content of chlorophyll and soluble protein as well as Pro decreased by 19.3%, 25.0% and 38.2%,respectively with application of high nitrogen treatment.The SOD significantly decreased, while soluble sugar content significantly increased,but MDA had no significant effect with the increase of ni-trogen application.E.hsienmu increased the content of soluble sugar in order to adapt to environment with ni-trogen application under cadmium stress.The adaptation of E.hsienmu promoted under low cadmium stress by adding low nitrogen.It was harmful for E.hsienmu under high cadmium stress by adding nitrogen or under low cadmium stress by adding high nitrogen.