Characteristics Of Soil Fertility Under Paddyfield Winter Conservation Tillage And Its Effects On Rice Senescence And Grain Quality

Conservation Tillage is a complete cropping system, which adopt conservational crop planting models and techniques to reduce water and soil erosion, protect environment. Ecological agriculture and agricultural sustainable development have become the developmental trend of future agriculture, and it is one of the realization measures to use organic manure participating in the nutrient circulation, resusing and soil fertility improvement in sustainable agriculture. Winter crops are resources of organic manure. Green-cover technique which can improve ecological environments and save energy is an important measure of realizing sustainable development of southern paddyfield. So, fully utilizing the paddyfield winter conservation tillage techniques, not only be able to alleviate the farmers' burden, but also be able to control the aeolian erosion and nutrient availability loss . The former studies of conservation tillage were mainly focus on the characteristics of soil fertility and ecological environment protection, while the researches of rice growth, physiological characteristics and quality in conservation tillage is still relatively little, especially in the rice senescence and quality which has not been reported so far. With the development of society, the high yield and quality of rice are the goal pursuited by farmers and experts. In order to study the effects of paddy winter conservation tillage on the rice growth, using rice variety guodaoliuhao as materials, we analysed the influence of four winter greencover plant on characteristics of soil fertility, rice senescence and quality with fallow as control(CK).; using early season indica rice of zhongzao22 as material, we studied the effect of organic fertilizer. The four winter green-cover plants are potato covered with straw(T1, fertilization of two years), oatgrass(T2, fertilization of one year), rape(T3, fertilization of two years), ryegrass(T4, fertilization of one year), which are common in Middle and Lower Reaches of the Yangtze River, The results are as follow:1, Compared to the control treatment, the organic significantly improved soil protease, phosphatase and catalase activities; During grain-filling stage, chlorophyll and soluble protein content, SOD activity in the leaves under organic nitrogen treatment decreased slowly, while POD activity increased quickly, MDA content changed little, which showed that organic fertilizer can effectively postpone the senescence of rice; The correlation analysis showed that it was significant correlation between the soil enzyme activities and the leaf senescence characteristics.2, Effects of returning straw on soil enzyme activities and rice integrated quality depends on the weight of straw returning and the fertilization life. There were significantly positive correlations between soil enzyme activities and rice comprehensive quality, with the soil protease activity had the most important effect on comprehensive quality, with significant correlation or very significant correlation in the latter part of grain filling stage especially. Soil enzyme activities in T 1 were higher than the other treatments, followed by T3. However, the activity in T3 is low, but it is stable and advantageous for the development of rice quality. And the comprehensive quality in T3 was the highest at 52.3 of quality index, the next are T1 and T2 with 51 and 49 respectively, and there were significant differences compared to the control treatment (CK).3, Returning straw can increase rice leaf SOD and POD activity, delay the degradation of chlorophyll and soluble protein effectively, and prevent the increasing of the MDA content during the grain filling. The significant correlation was widely found between the soil enzyme activities and leaf senescence in the research and the soil protease activity had the most effect on the leaf senescence, which showed significantly or very significantly correlated between the soil protease activity and leaf senescence in the mist and late grain filling, especially. The results show that T1, T2 and T3 can better delay the rice leaf senescence, and their yield reached 12.27 t/hm~2, 12.30t/hm~2 and 12.21t/hm~2 respectively (Compared to the control treatment (CK), there were significant differences). Correlation analysis showed that there was significant or very significant positive relationship between rice yield and leaf senescence. 4, Compared to the control treatment (CK), different previous crops played a great role in promoting dry weight accumulation, leaf area index and leaf weight of rice, but T1 had the most important effect on the rice growth, followed by T2; The root activities was higher, Chlorophyll content decreased more slowly in T1 and T2 than the other treatments; In grain filling, the initial potential was large and the average grain filling rate was fast, it is helpful to enrich the grain.