Study On The Screening Of Low Accumulation Rice Cultivars

In recent years,the problem of excessive heavy metal content in rice has frequently appeared,and the quality and safety of rice have attracted much attention.A field experiment was conducted in order to investigate the accumulation of heavy metals(Cd,Pb,Ni,Cu,Zn,Fe,Mn)in 15 rice cultivars from the contaminated soil.The main factors affecting the accumulation of heavy metals by rice were discussed.This study was aimed to provide a basis for the safe use of heavy metals polluted agricultural soil.The main results were as follows:(1)The Mn accumulation ability of the tested rices was the highest,the Pb accumulation ability was the lowest,and the accumulation ability of the all other heavy metals was modest.The elements were mainly concentrated in roots(except Zn,Mn).The Cd in all brown rice did not exceed the standard;except for Taigeng 8,the Pb content in brown rice did not exceed the standard.(2)Considering comprehensively the rice accumulation ability of heavy metals and the yield of rice grains,it was found that Taigeng 8 was a low-yield cultivar with low accumulation of Cd,Ni,Mn and Fe.Yiyou 673 and Donglian 5 were a high-yield,low Cd-Zn accumulation cultivars.Huayou 63 was a high-yield,low Cd-Pb-Cu-Mn-Fe accumulation cultivar.Chunyou 84 was a high-yield,high Cd-Pb-Ni-Cu accumulation cultivar.Zheyou 18 was a high-yield,low Ni-Cu-Zn-Fe accumulation cultivar.Yongyou 9 was a cultivar with high-yield and low accumulation of Pb,Ni and Cu accumulation cultivar.Guangyou 673 was high-yield,low Cd-Ni accumulation cultivar.In the Cd-Pb compound contaminated soil,Yiyou 673,Donglian 5 and Huayou 63 can be selected preferentially.(3)Different rice cultivars had different amounts of Fe-plaque on its root surface.The higher amount of the Fe-plaque formed on the root surface,and the higher contents of Cd,Pb,Ni,Cu and Zn also were in the Fe-plaque.The contents of Cd,Ni,Zn and Mn in the roots increased with increasing contents of Cd,Ni,Zn and Mn in Fe-plaque.However,the Pb content in roots tended to decrease with increased Pb content in Fe-plaque,suggesting that the Fe-plaque favors the uptake of Cd,and hinders the uptake of Pb by roots.(4)The accumulation of the heavy metals in the brown rice related to the transfer characteristics of the metals within the parts of soil-rice system.The Cd and Ni concentration increased with increasing transfer ability of Cd and Ni from leaves to rice grains.However,the transfer characteristics influencing the accumulation of the other metals in the brown rice were not clear.