Tolerance And Accumulation Characteristics Of Cadmium In Herbaceous Plants

This research has selected 36 kinds of common herbaceous plants and two hyper-accumulator plants as materials, the tolerance and accumulation characteristics of cadmium in herbaceous plants were studied with pot experiment method in outdoor. The tolerance and accumulation characteristics of cadmium in herbaceous plants, the absorption and transport mechanism of cadmium were primarily analyzed. On the basis of single stress,6 plants with high-absorption and high-tolerance features were selected and the plant’s tolerance, accumulation characteristics and root morphology under multi-gradient cadmium stress were analyzed and the tolerance threshold and super-rich features were estimated. The main results are as follows:1) The herbaceous plants have a higher tolerance to cadmium, only 9 species of plants were significantly inhibited in the herbaceous plants that selected before. Cadmium absorption and accumulation were different, and the variation coefficient of cadmium content and accumulation in shoot were 30.9% and 64.5% respectively. The highest cadmium accumulation in shoot is Lolium multiflorum witch is 3.4 times to hyper-accumulator plant Solarium nigrum,4.1 times to Brassica juncect, which indicates that part of the herbaceous plants have a high absorption capacity for cadmium.2) The total cadmium uptake and aboveground biomass had significant correlation, the correlation coefficient was 0.842, and linear regression analysis also reached extremely significant level, and the R2 was 0.7084. It indicates that the absorption of cadmium affected by aboveground growth. The cadmium content in shoot is affected by both total uptake and transport coefficients.3) Under the multi-gradient cadmium stress, the plant biomass showed a general downward trend with the increase of cadmium concentration while the content of Cd in the shoot and the root Cd content showed a linear increasing trend.6 species of herbaceous plants were sensitive to cadmium, the biomass is decreased significantly at the 50mg/kg treatment concentration. The cadmium content in shoot of Buchloe dactyloides and Lotus corniculatus can reach more than 100 mg/kg at the concentration of 100mg/kg treatment. Root morphology showed that the total root length, root surface area, root volume decreased, the average diameter of root, the number of root tips promoted under low concentration and inhibited in high concentration.