人参生长与生理特性对镉胁迫的响应

Effects of cadmium stress on growth and physiological characteristics of Panax ginseng

目的研究重金属镉(Cd)胁迫对人参生长及生理特性的影响。方法通过筒栽试验,对不同质量分数Cd处理(0、0.3、1.0、2.0、4.0 mg/kg)下人参的生物量、叶色值(SPAD)、抗氧化酶活性及丙二醛(MDA)进行测定与分析。结果随着Cd胁迫质量分数的增加,人参相对生长率呈现逐渐降低的趋势,与Cd添加质量分数之间呈显著负线性相关(P<0.05);人参叶片SPAD值呈降低趋势;而人参不同部位抗氧化酶活性及MDA量均有不同程度的升高,根和叶的MDA量与Cd质量分数呈显著正线性相关(P<0.05)。同一Cd水平处理下,人参不同部位MDA量表现为叶>茎>根。结论人参具有适应一定Cd质量分数(≤1.0 mg/kg)胁迫土壤环境的能力,此时可增强自身抗氧化酶活性等生理生化反应来清除活性氧,保持膜稳定,缓解Cd胁迫带来的伤害;然而在处理质量分数>1.0 mg/kg时,人参MDA量显著增加,氧化损伤严重,影响植物生长,导致人参生物量下降。

Objective To investigate the effects of cadmium（Cd） stress on the growth and physiological characteristics of Panax ginseng（ginseng）. Methods Two-year old ginseng was cultivated in barrels in phytotrone with different concentration of Cd（0, 0.3, 1.0, 2.0, and 4.0 mg/kg） soil for a whole growth period. In red fruit stage, the contents of biomass and SPAD, the activities of anti-oxidant enzymes, and contents of malondialdehyde（MDA） were determined and analyzed. Results With Cd concentration increasing, the relative growth rate of ginseng expressed a slowly decreasing trend, and showed negative linear correlations with Cd stress level（P〈0.05）; The SPAD value of ginseng showed a decline; But the activities of anti-oxidant enzymes of different parts of ginseng and the contents of MDA decreased on different levels. The contents of MDA from leaves and roots showed linear correlations with Cd stress level（P〈0.05）. Contents of MDA in different positions of ginseng showed as： leaf stem root. Conclusion Ginseng has an adaptability to the contaminated soil with Cd（≤ 1.0 mg/kg）, and at this time ginseng can enhance the activity of anti-oxidant enzyme and other physiological and biochemical responses to eliminate reactive oxygen species, maintain stability of the cell membrane, alleviate the harm from the stress of Cd; Though with Cd（ 1 mg/kg）, the contents of MDA could increase significantly, and the oxidative damage of ginseng is very serious. The growth of plants is affected, resulting in a decline in ginseng biomass.