Effects Of Rice Blast On Dynamic Ion Absorption Of Rice Seedling

Rice varieties KY131,KY163,SJ8 and LJ26 were taken as experimental materals in this paper. We detected the changes of K+、Ca2+、NH4+、NO3-、H+flux at root apical regions of four varieties of rice seedlings infected rice blast by Non-invasive Micro-test Technique, and determined the conventional physiological and biochemical indexes of SPAD value, potasslum content,calcium content,chlorophyll content,proline content and soluble sugar content. According to the comparative analysis on the experimental results, we discussed the effects of rice blast on ion flux of rice seedlings and the relationship between mean ion flux and corresponding physiological indexes. Then find out significant differences of ion flow between resistant varieties and susceptible varieties, and thus lay a foundation for rapid screening disease-resistant rice and cultivateing new resistant varieties. At the same time, this research provides the theory basis for monitoring and warning of rice blast happened and disease controlling.Based on the experimental results, we have preliminary obtained the following conclusion:1. After infected the rice blast, K+influx of rice seedlings decreased, even display efflux; susceptible varieties show Ca2+efflux, while Ca2+influx of resistant varieties enhanced. This difference can be used to screen disease-resistant rice; ion flux of NH4+turns to efflux, while NO3- influx decreased. This shows that rice seedings used the nitrate nitrogen as a nitrogen source after infected the rice blast; H+ which is used to homonymous transport across membrane ion reduced that possibly leads to H+efflux. These changes of ion flux are significant differences of rice seedings in the absence or presence of rice blast, which can be used for monitoring the blast happened. 2. After infected the rice blast, K+content in each part of rice seedlings reduced, and K+content of the ground part (cauline leaf)declined more significantly. Ca2+content in each part increased obviously, and Ca2+content in root increased more sugnificantly. Ca2+content gap between the ground part and root reduced. Ca2+content increased rate was certain different between different resistant varieties. Among them, the change of Ca2+content of resistant varieties was more intense. From this, we consider that Ca2+plays an important role in rice seedling resisting disease.3. After infected the rice blast, SPAD value in four varieties of rice seedings all decreased significantly, and LJ26 declined smallest. Photosynthetic pigment content in four varieties of rice seedings all decreased and the decreasing amplitude were different. Resistant varieties declined obviously less than susceptible varieties. Compared with carotenoids, the damage or inhibition effect of blast on chlorophyll is more apparent.4. The rice blast stress can cause significant increase in the proline content of rice seedlings and we find that proline content of resistant varieties higher than susceptible varieties. From that the accumulation of proline in rice seedlings is a adaptation response to cope with disease stress. However, After infected the rice blast, the change regularity of soluble sugar content of rice seedlings is not obvious, which suggests that the influence of soluble sugar is not significant in rice seedling resisting disease.