| Find out the plant which has high biomass and high absorption efficiency of heavy metals contributes to enhance the efficiency about plant extraction. In this study, Corchorus capsularis L.was taken as experimental material, discussed the growth and photosynthesis under different concentrations of cadmium by pot experiment, analysised the cadmium accumulation characteristics of C. capsularis. In order to investigate the physiological response process and revealed the mechanism of resistance of C. capsularis under cadmium stress, the different levels and treatment time hydroponics experiments were carried out. The main results showed as follows:(1)The plants height and roots length of C. capsularis. decreased with increasing Cd concentration, but a slowly decrease in low concentration, the plants height decreased by 6.34%,8.98%,13.93%,33.62%,39.41% comparised with control. The roots length decreased by 5.36%,9.53%,24.87%,37.50%,50.41% compared with control, respectively. The biomass of each organs showed as stems> roots> leaves. The biomass decreased gradually with increasing Cd concentration, and the stem showed a slow descending tendency.(2) The Cd concentrations in roots, stems and leaves elevated with the Cd concentration, the Cd concentrations in different organs showed as stems> roots> leaves, and reached the maximum at the concentration of 100 mg·kg-1, for the 261.92 mg·kg-1, 186.98 mg·kg-1,102.97 mg·kg-1, respectively. The Cd concentration in the stems of C. capsularis showed upside> middle> bottom, which showed the good ability in Cd upward conveying of C. capsularis. The accumulation of Cd in C. capsularis reached 3.83 mg·plant-1 at the treatment of 50 mg·kg-1.The BCFs of C. capsularis at each concentration were greater than 1, and accorded with hyperaccumulator.(3) The O2- produce rate of leaves increased with the increasing Cd concentration and processing time, significantly, but a complex trend in roots, it showed a trend of rised first and fell later process generally. The H2O2 content in roots and leaves increased with the increasing Cd concentration and processing time. MDA showed a same tendency as H2O2.(4) From the point of antioxidant enzymes, with increasing Cd concentration and processing time, APX activity enhanced unceasingly; GR activity reached the maximum at T1 (25μM), but decreased with increasing concentration and time. From the point of antioxidation substances, AsA content in roots also increased with the increasing of the concentration and time, but reduced after the first rise trend generally in leaves; GSSG content and GSH content were higher than the control significantly.The soluble sugar, soluble protein showed reduced after rised first trends with concentration and time.(5) Chlorophyll a, chlorophyll b and total chlorophyll were decreased with the concentration and the biggest drop in chlorophyll b. Chlorophyll a/b increased with the increasing Cd concentration, so as to improve the light energy utilization of C. capsularis under Cd stress. The Pn, Gs and Tr are reduced after the rising trends, Ci was rising with concentration. The C. capsularis was obtained by the Ls and Ci changes of photosynthesis decline which caused by non stomatal restriction factors.Above all, in order to strengthen the ability against the stress of Cd, C.capsularis utilized initiating mechanism of antioxidant defense and osmoregulation.The strong accumulation ability to Cd of C.capsulari was shown and the BCFs were greater than 1 at each concentration, the highest accumulation of Cd in aboveground reached 3.83mg·plant-1.Therefore, C.capsulari is a potential useful material for phytoremediation. |
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