Study On Ecological Effect Of Rice Rhizosphere Microbes With N Application Level And Water Regimes

Rice is an important cereal crop for human being. The microbes in the rhizosphere of rice play a key role in the nutrition flow between the soil and plants. Nitrogen and water are major factors for maintaining crop yield, getting better economic return. The ecological effect of rice rhizosphere microbes with N application levels was analyzed in paddy field. Meanwhile, the ecological effect of rice rhizosphere microbes with N application and water regimes by rhizobox at pot experiment was also studied. The results from the field and pot research indicated that It is a preparative for understanding the paddy field eco-system behavior, knowing the nutrition fluxion precisely and protecting the rice field environment. The major results were listed as foliowings:1) The ecological effect of rice rhizosphere microbes is not only affected by rice rhizosphere microbes population but also affected by the growth of the rice. In general, there is a competition on nutrition between the rice and the rice rhizosphere microbes in the rice tillering stage and filling stage. As a result, the ecological effect of rice rhizosphere microbes descends.2) split N fertilizer application will result in the ecological effect of rice rhizosphere microbes decline. Under split N fertilizer application, the conversion of urea to NH⁴⁺ and the enrichment of the NH4+ in the rice rhizosphere needs time, which will then induce an alkalescent surroundings in the rhizosphere. The alkalescent environment will produce a stress on the rice rhizosphere microbes and decline their livability.3) The microbial biomass C content in rice rhizosphere changed as the rice grows.4) The microbial biomass C, phosphatase, urease, total protein, total phenol content in rice rhizosphere are affected by split N fertilizer application. There is an obvious difference between N and no N treatment in the latest rice growth periods after fulfillment the N fertilizer.5) The various trend of the index of ecological effect of rice rhizospheremicrobes in the different rice growth stage at pot experiment differs in different water regimes. In the pot situation, the ecological effect of rice rhizosphere microbes is affected not only by the rice root and the N fertilizer application, but also by the water regimes.6) The microbial biomass C, phosphatase, urease, total protein, total phenol content in rice rhizosphere during the growth of the rice are not only affected by the water regimes and the N fertilizer levels separately, but also affected by the crossed action between the two factors. The factor N, in general, can show a notable affection on the ecological effect of rice rhizosphere microbes in the tillering stage. The effects of the water regimes produced little in this period and begin to be seen in the filling stage of the rice. Because the rice needs a lot of nutrition in the filling stage, but the split fertilization of the N fertilizer made the absorbed N occupied a little in the total nutrition, the factor N doesn't work so well in this period. After the rice ripe, the fact that the rice is not only affected by the water regimes and the N fertilizer fertilization, but also affected by the crossed action between the two factors indicates that both of the N fertilizer and the water regimes have accumulated influence on rhizosphere effect.7) Because there is an accumulated influence of water on the growth of rice, after the ripeness of rice, the depth of the effect of the different factors doesn't goes on the same way when compared in different ways using different indexes. Generally speaking, the water regime has the stronger effect on the ecological effect of rice rhizosphere microbes, but as for the urease, the N fertilizer is the key factor. This is related to the increase of the substrate matter, the enhancement of the activity and the enrichment of the enzyme. The order of the extent of the effect of the crossed action and the N factor does not show the same trend when using different indexes.8) After ripeness, the controlled water mode can enhance the content of the phosphatase, urease, total protein, total phenol content in rice rhizosphere notablely, but the content of the microbial biomass C reaches the top level under the dry and wet alternative controlling situation mode, "While the-five riec rhizosphcrc effect-indoxos shewed-feek- bottom levels when thcxOTitnmetts-imgation mode was adopter! duringriee-gfowth stage;All of these results showed that an appropriate control of water could benefit rice growth and the maintain the fertility of the soil.