Study On Growth Period Of Cadmium Accumulation And Mitigation Of Cd Assimilation With Bio-fertilizer And Lime In Brown Rice

This study was made for analyses of period of rice grain Cd accumulation and for seeking amendments for controlling Cd pollution. Selection of appropriate Cd concentration for whole growth duration nutrient solution tests of rice were based on the analyses of effect of Cd stress on rice seed and seedling growth that were got from the tests of different Cd concentration stress on seed germination and seedling cultivation. Contribution rate of different growth duration on Cd accumulation of rice grain was caculated by comparison and mutual authenticating based on theory of "subtraction" between the test of adding exogenous Cd after different growth stages of rice and the no adding test. And tests of influence of basal bio-fertilizer and lime dressing on Cd accumulation of rice grain were made to be the theoretical basis and technical reference for resistance control of accumulation of rice grain Cd. The main results of the study were as follows:?1? Rice seed germination test and seedling cultivation experiment were made to study the effect of Cd content on rice germination and seedling growth of seeds by inflicting defferent concentrations of Cd stress on rice seeds during the bud and seedling stage. The results showed that 5 mg-L^-1 is the critical Cd concentration for inhibition of seed germination. The bearable Cd stress concentration range of rice seed germination stage is 0-5mg-L^-1.And lmg-L^-1 is the critical concentration that has significant impact on rice seedling root length, seedling height, and biomass. The increase of the seedling Cd accumulation growing normally was related to that of Cd concentration. The concentration of 0.05mg L^-1 could factually reflect the normal rice accumulation.?2? Test of adding 50 ?gL^-1 exogenous Cd after different growth stages of the rice ?yu zhen xiang? was made to study the influence of the accumulation of Cd. The results showed that Cd concentration of each part of the rice plants not only changed with but also was significant positive correlation of the time length of rice inflicted Cd stress. The same gradient changes occurred in each part of rice plants Cd accumulation?straw parts:root> stem sheath> leaf; and grain parts:chaff> brown rice?;56.27%Cd content of chaff from tillering stage while 18.69%from heading and flowering stage, and 35.11% of brown rice from tillering stage while 26.61% from grain filling stage.?3? Test of no adding exogenous Cd after different growth stage of the rice ?Xiang Wanxian No.13? was made to study the influence of the accumulation of Cd. The results showed that exogenous Cd concentration of 50 ?gL^-1 did not obviously influent the rice normal growth; The change of accumulated Cd concentration of rice plant was linear with the length of time that rice inflicted Cd stress; Accumulated Cd content of each part of pant: root> stem sheath> leaf> chaff> brown rice; 43.64%,24.06%and 14.21%Cd content of chaff from maturation stage, tillering stage and heading stage, respectively 36.36%,18.18% and 16.36 Cd content of brown rice from tillering stage, filling stage and maturation stage, respectively.?4? The field random plot experiments were applied in this study. The effect of base bio-fertilizer ?Bi?, lime ?L?, base bio-fertilize bio-fertilizer combined with lime ?Bi+L? on rice biomass and ability of late rice enrichment on soil Cd, cadmium ?Cd? migration trend in 4 growth period and translation coefficient between organs were studied. Results showed that compared with CK, the treatment group were biomass had no obvious effect on rice, and the Cd content of different parts of rice has remarkable resistance control effect, can effectively reduce rice Cd concentration in the different parts of the soil, reduce the content of Cd in rice chaff significantly. The best effect is ?Bi+L? can processing of Cd content in brown rice rate was 84.76%, to meet the national food hygiene standards.