Study On The Difference Of Cadmium Absorption In Different Cultivars’ Rice Of The Northeast Region

In order to provide theoretical and practical basis for breeding rice varieties with high tolerance to cadmium resistance and low accumulation, a pot experiment was conducted with 5 different rice cultivars of Liaoning Province under soil exogenous cadmium added conditions. The differences of cadmium accumulation in different parts of rice were investigated; meanwhile the contents and distribution in subcellular fractions of rice were analyzed to further reveal the mechanism. Results showed that,(1)Liaoxing 1,Shennong 15 and Shennong 315 drop less in the total grain yield and biomass affected by cadmium, have a less influence and strong resistance to cadmium; By contrast, Shendao 47 and Liaojing 9 drop more in the total grain yield and biomass affected by cadmium, have a greet influence and weak resistance to cadmium;(2)The cadmium content in each part of rice was increased with increasing applied cadmium amount and the differences were significant; there were significant differences in cadmium accumulation coefficients in grain of different cultivars rice, there was a downward tendency of the cadmium accumulation coefficient with increasing applied cadmium amount, among which Shendao 47 and Liaojing 9 were relatively high, while Liaoxing 1,Shennong 15 and Shennong 315 were low, and Shennong 315 was the lowest under all treatments; Grain of cadmium adsorption ability with the increase of the adding exogenous cadmium concentration, within a certain range will decrease, differences between each type has a weaker trend.(3) With the increase of the adding exogenous cadmium concentrations, different cultivars rice transport coefficient decreases under Cdl processing first, gradually increasing under Cd2 and Cd3 after Cdl treatment. All treatments, Shendao 315 transfer coefficient is minimum, the root transfer ability is low, immobilize most of the absorption of cadmium in roots. Under Cd3 treatment, Liaojing 9 transfer coefficient is the first place, Shendao 47 comes second. Under the high concentration of cadmium treatment, Liaojing 9 and Shendao 47 root transfer ability are strongest.(4) The cadmium content in subcellular fractions of shoots in heading stage was lower than that in tillering stage, the cell wall was the largest, the soluble part was the second, and the organelle is the smallest. From the point of allocation proportion, most of cadmium exist in the cell wall and cell organelles, After adding cadmium treatment, the content of each cell component are increase, the distribution proportion in cell wall is increase, cell organelles and soluble substance are reduced, and the organelles distribution range drops more, most of cadmium is still distribute in the cell wall and soluble substance.(5) The cadmium content in subcellular fractions of roots in heading stage was higher than that in tillering stage。Without adding cadmium content in each cell components at the highest of cell wall, cell soluble components,organelles minimum; adding cadmium treatment, cadmium in the cell is slightly larger than the cell wall in the soluble components. From the point of allocation proportion, most of the cadmium is present in the cell wall and cell soluble components, accounts for only a small part of organelles in proportion.Without adding cadmium, the percentage of cell wall is first place, cell soluble comes second. By contrast, the percentage of cell wall is reduced, cell soluble component is increase, and slightly larger than the cell wall. The most of cadmium are in the cell wall and cell soluble components.(6) The content and distribution proportion in subcelluar fractions of rice are different in different cultivars and growing stage, cadmium content and distribution proportion in the cell wall and soluble part of cadmium tolerance rice variety Liaoxing 1,Shennong 15 and Shennong 315 were higher than those of sensitive variety Shendao 47 and Liaojing 9, organelles were lower than sensitive varieties.(7) In mature stage, the cadmium content between shoot cell wall and grain are significantly negative correlation relationship, the greater the cadmium content of cell wall, the smaller the cadmium content in grains, the cell walls of cadmium content difference can reflect the mature grain of cadmium content.