Effects Of Organic Manure On The Development And Accumulation Of Cadmium In The Different Rice Types Under Cadmium Stress

Rice is the main food crop in China, and also posses the strongest cadmium accumulation in the staple crops. In recent years, damage to crops caused by cadmium and their response have particularly attracted more attention. Different rice types, zhendao88and Eryou107, were used to study the effects of cadmium and organic manure on the growth, physiological characteristics in heading stage and mature stage, yield and yield components, concentration and accumulation of cadmium in rice by two years pot experiments, in order to elucidate the mechanism of cadmium injury and the remission of organic manure to rice, and further provide theoretical basis and technical support for in the actual production of rice. The results were as follows:1. Compared to cadmium free treatment, it occurred that the significant reduction of the dry matter accumulation and yield in two rice types under cadmium stress (cadmium:3.0mg/kg), where the grain yield of Zhendao88and Eryou107were dropped by13.90%and13.74%respectively, for the decrease of panicle number per plant, seed setting rate,1000-grain weight, and the number per spike of Eryou107. Organic-inorganic-mixed fertilizer, made the initial heading stage of two types of rice in advance and the accumulation of dry matter at different growth stages significantly increased. Organic manure may significantly rose theoretical yield with the increase of the panicle number per plant in cadmium free treatment and seed setting rate as well as spikelet number per panicle besides it under cadmium stress. Otherwise, it showed different effects of cadmium and organic manure on two rice types.2. Under cadmium stress, antioxidative enzyme activities, non-enzyme antioxidant contents, chlorophyll content and photosynthetic rate all decreased gradually, while MDA content of rice increased significantly. Organic manure made SOD and POD and CAT activity and GSH, soluble protein content, chlorophyll content and photosynthesis physiological characteristics increased differently, while MDA content reduced, especially in heading stage. But two rice types showed some differences in mitigating mechanism about organic manure.3. Under cadmium stress, the concentration of cadmium in various organs of plant and distribution ratio of cadmium in root and milled rice significantly increased. Organic manure had no significant effects on the concentration of cadmium in vegetative organs of the treatments with no exogenous cadmium (background concentrations of soil cadmium0.202mg/kg), such as slightly decreased that in panicle. Fortunately, organic manure could reduce the concentration of cadmium in vegetative organs, bran and milled rice, and increase the distribution ratio of cadmium in vegetative organs, and however there was a decrease of that in panicle under cadmium stress. For panicle, it also partially increased the distribution ratio of cadmium in chaff and bran, and decreased that in milled rice. In addition, organic manure could significantly reduce the enrichment coefficient of cadmium in single stem of Eryou107. Therefore the final suggestion was organic manure significantly decreased the concentration of cadmium in milled rice by reducing available cadmium in the soil and inhibiting cadmium transport from root to above-ground and above-ground to milled rice. Furthermore, the effects of organic manure in the two different rice types were different.