The Characters Of Cadmium Accumulation And Partitioning In Ratoon Rice And Its Differences Among Varieties And Nodes

Taking the combination of field test and cadmium-free liquid culture,in 2019-2020,the cadmium distribution characteristics of 15 ratooning rice varieties and the differences between varieties,ratooning nodes and between the first season rice and ratooning rice were systematically analyzed,with a view to providing a basis for rational selection of varieties and cadmium reduction measures in production practice.The main conclusions are as follows.（1）The accumulation and distribution characteristics of cadmium in ratoon rice:There areobvious differences in the cadmium accumulation and cadmium enrichment coefficient of plants among different rice varieties,and the 5 varieties for trial in 2020 are shown as the Yongyou 4949>Q Liangyou 1606>Quanyousimiao>Quanyou 1606>C Liangyousimiao.Cadmium content in brown rice and milled rice of Q Liangyou 1606 and Yongyou 4949isthe highest at lower nodes,the other 3 varieties show that cadmium content in the upper nodes is higher than in the lower nodes,and the lowest is that of the 4^th nodes.（2）The cadmium accumulation and distribution characteristics of ratooning rice and first-season rice:the cadmium content of each organ in the first rice follows the law of root>stems>leaves>brown rice>fine rice,and the cadmium content of organs of ratooning rice generally follows the law of root>rice piles>stems>leaves.The cadmium content of brown rice in ratooning rice is lower than that of first-season rice,and the cadmium transport coefficient of ratooning rice is shown as TF stem/rice pile>TF fine rice/brown rice>TF leaf/stem>TF brown rice/stem,of which TF spike/stem and brown rice/spike show that ratooning rice is larger than first-season rice.（3）The cadmium accumulation of cadmium-free liquid-cultivated rice is much lower than that of field-cultivated ratooning rice.Compared with the cadmium-free liquid culture,the cadmium accumulation in the stems and leaves of the second and third nodes in the field test was 2.49 times～2.64 times and 22.06 times～82.32 times that of the plants cultured in cadmium-free liquid.The accumulation of cadmium in the stems and leaves of the 4^th nodes was 1.39～15.79 times and 5.95～38.49 times respectively.The accumulation of cadmium in the stems and leaves of the5^thnodes was 0.83～3.84 times and 6.91～31.03 times respectively.The accumulation of roots and rice piles was 2.47～8.19 times and 1.39～15.79 times of that of cadmium-free liquid culture,respectively.The accumulation of cadmium in the whole plant of ratooning rice,cadmium-free liquid cultivation is 15%to 38%of the field test.It is implied that the absorption and accumulation of cadmium from the soil continues during the growth phase of ratooning rice.