3种土壤下巨菌草对镉胁迫的生理响应

通过盆栽试验研究了四川盆地3种典型土壤(冲积土、紫色土和黄壤)不同浓度镉(Cd)处理(0、20、50、100 mg·kg~(-1))对巨菌草植株生长的影响以及对抗氧化酶、丙二醛(MDA)、可溶性糖、可溶性蛋白和叶绿素等生理生化指标的影响。结果表明:3种土壤条件下,20 mg·kg~(-1)的Cd处理浓度对巨菌草的生长未造成显著影响,而随着处理浓度的增加,巨菌草的生长受到了显著的抑制作用;巨菌草地上部和地下部生物量随着Cd处理浓度的增加而呈现下降趋势,各部分生物量的降幅表现为黄壤紫色土冲积土。巨菌草地上部与地下部植株Cd含量随着Cd处理浓度的增加而显著增加,且表现为黄壤紫色土冲积土。巨菌草叶片中超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)的活性均随着Cd浓度的增加呈先升高后降低的趋势;随着Cd处理浓度的增加,可溶性蛋白含量呈下降趋势,而丙二醛(MDA)和可溶性糖的含量则表现出上升趋势。总体来看,巨菌草对Cd污染具有一定的忍耐力和富集吸收作用,3种土壤类型中巨菌草对Cd的生理响应有所差异,但与其他2种土壤相比,冲积土中生长的巨菌草抗氧化酶活性的变化幅度和MDA含量都比较低,可溶性蛋白、叶绿素含量相对较高,表现出较强的耐Cd性。

Physiological Responses of Pennisetum spp. to Cadmium Stress in Three Types of Soils

Pennisetum spp is an adversity-resistant perennial energy plant. However, there is little information available about its physical responses to cadmium(Cd) stresses. A pot experiment was designed to study the effects of Cd at different concentrations(0, 20, 50 and 100 mg·kg^-1) on the growth and physiological indexes, including antioxidant enzyme activity, and MDA, soluble sugar, soluble protein and chlorophyll content of Pennisetum spp grown in three types of soils(alluvial soil, purple soil and yellow soil). Results showed that the growth of Pennisetum spp was not significantly influenced by Cd up to 20 mg·kg^-1, but it was significantly inhibited at higher Cd concentrations in all three soils. The belowground and aboveground biomass of Pennisetum spp decreased with increasing Cd concentrations. Such reduction was in order of yellow soil >purple soil >alluvial soil. The content of Cd in Pennisetum spp increased with increasing Cd concentrations, with increment being yellow soil >purple soil >alluvial soil. The activities of superoxide dismutase(SOD), peroxidase(POD) and catalase(CAT)increased at low Cd but decreased at high Cd concentrations. As Cd concentrations increased, soluble protein decreased whereas soluble sugar and malondialdehyde(MDA) increased. Overall, Pennisetum spp had certain tolerance to and absorption and bioaccumulation of Cd in contaminated soils. The physiological responses of Pennisetum spp to Cd were different among three soils. Antioxidant enzyme activity and MDA content were lower, but soluble protein and chlorophyll content was higher in alluvial soil than in other two soils.