Tolerance And Accumulation Characteristics Of Different Species Of Ricinus Communis L. Under Cd Stress

Heavy metal such as cadmium pollution is a significant environmental problem and has a negative impact on human health. In order to investigate the tolerance and accumulation characteristics of five species which are Ricinus communis L.of Hanyuan(HY), Space castor NO.189(SD), Yunnan (YB), Thailand207(TG) and Red No.4(YZ) under Cd stress, the plot experiment is taken. The main results were showed as follows:Ricinus communis L. of five species grew normally when the Cd concentrations≤100mg kg-1. The leaves of plants showed the symptom of yellow and withered at150mg kg-1. TG and YZ injured more seriously and were led to death at the concentration of Cd≥200mg kg-1. The root projected area, root surface area and root volume of TG decreased with the increasing of Cd concentration, while the rest four species increased first and then decreased. Root length of five species increased first and then decreased with the increasing of Cd concentration, but plant height tended to decrease in the third month. Except that the shoot biomass of YZ decreased with the increasing of Cd concentration, the rest four species increased first and then decreased.With the increasing of Cd concentration, Pn, Cond and Trmmol of five species all tended to increase first and then decrease while Ci decreased first and then increased. With the increasing of Cd concentration, POD, CAT and SP in roots and leaves of five species increased first and then decreased. But with the increasing of Cd concentration, GSH of different species presented different trends. Under the Cd stress, POD, CAT, SP and GSH in roots and leaves of five species were roots<leaves.With the increasing of Cd concentration, the content of Cd in roots and leaves of five species increased gradually, and root> shoot. Among them, the highest Cd contents of roots in HY,SD and YB were234.61,243.78and292.47mg kg-1, while it was below170mg kg-1in TG and YZ. The highest Cd contents of shoots in HY, SD and YB were234.61,243.78and292.47mg kg-1, it was below60mg kg-1in TG and YZ.With the increasing of Cd concentration, Cd accumulation in roots of five species took on the trend to increase, besides the Cd accumulation of HY and SD in shoots increased gradually, the Cd accumulation of YB, TG and YZ increased first and then decreased, and roots<shoots. Among them, the highest Cd accumulation of roots in HY, SD and YB were0.59,0.70and0.51mg pot-1, while it was below0.30mg pot-1in TG and YZ. The highest Cd accumulation of shoots in HY, SD and YB were1.23,1.02and0.91mg pot-1, it was below0.40mg pot-1in TG and YZ. Generally speaking, HY, SD and YB had strong tolerance accumulation ability under low and middle concentration of Cd.The shoots BCF in HY, SD and YB were0.34to0.71,0.23to0.73and0.30to0.57. The TF were0.42to0.71,0.27to0.49and0.29to0.39. The shoots BCF and TF in TG and YZ were between0.33-0.80and0.28-0.67.