Screening Of Rice Varieties For Efficient Use Of Organic Fertilizer And The Characteristics On Organic Nitrogen And Phosphorus Utilization

Excessive use of chemical fertilizers,causes not only waste of resources,but also environmental problems.Substitution of chemical fertilizers with organic fertilizers to keep efficient use of organic resources are important ways and decrease chemical fertilizers,as well as keep sustainable agriculture.There are many genotypes of rice in China,which have different efficiencies utilization of organic fertilizer.Rice varieties have better characteristics under organic fertilizer with high efficiency of organic fertilizer utilization.Based on the existing screening materials,this study used the chemical fertilizer and organic fertilizer at the same nutrients of nitrogen,phosphorus and potassium application in the field to study the responses of rice to nutrient forms between organic and inorganic fertilizers.Compared to chemical fertilizer application,the response of yield,absorption and utilization efficiency of nitrogen,absorption and utilization efficiency of phosphorus,in organic fertilization application were analyzed to screen efficiency varieties to organic fertilizer.Pot experiments were carried out on the selected rice materials to study the response of urease,acid phosphatase and phytase activities in the root system and rhizosphere soil under organic fertilizer application.Then we analyzed the changes in the expression levels of acid phosphatase and phytase encoding genes in rice roots under different fertilization application in order to explore the utilization characteristics of organic nitrogen and organic phosphorus nutrients by rice varieties with different organic fertilizer use efficiency.The results of the study are as follows:1.Field experiment were carried out to study the response of 33 rice varieties to organic fertilization.The results showed that 3%-15% of rice varieties are potential efficient varieties of organic fertilizer on yield,biomass,tiller number,ear weight,and plant height.There were 6%-29% of rice varieties in organic fertilizer application close to that in chemical fertilizer application,which were also organic fertilizer efficiency varieties.There were 60.1%-90.3% of rice varieties decreased on yield,biomass and tiller number etc.in organic fertilizer application than that in chemical fertilization.2.There were 58% and 79% of varieties of nitrogen and phosphorus content in stem and leaf increased in organic fertilization than that in chemical fertilization,respectively.There were 26% and 16% of varieties of nitrogen and phosphorus content in stem and leaf did not change in organic fertilization than that in chemical fertilization,respectively.While 16% and 5% of them decreased in organic fertilization than that in chemical fertilization,respectively.There were 47% and 26%of varieties of nitrogen and phosphorus content in grains reduced in organic fertilization than that in chemical fertilization,respectively.There were 53% of varieties of nitrogen and phosphorus content in grains did not change in organic fertilization compared to that in chemical fertilization.There were 21% of varieties of phosphorus content in grains increased in organic fertilization than that in chemical fertilization.Therefore,nutrients transfer from leaves to grain decreased when organic fertilizer application.3.There were 6%-11% of varieties higher in nitrogen and phosphorus absorption and utilization efficiency in organic fertilization than that in chemical fertilizers application,which suggested potential organic fertilizer efficiency.There were6%-22% of varieties did not change in nitrogen and phosphorus absorption and utilization efficiency.There were 72%-89% varieties of nitrogen and phosphorus absorption and utilization efficiency reduced in organic fertilization compared with that in chemical fertilization.4.According to responses of the varieties on yield,nitrogen absorption and utilization ratio,phosphorus absorption and utilization ratio in organic fertilizer application,potential organic fertilizer efficient varieties were selected as No.2,No.12,No.21,No.27 and No.33,and inefficient varieties were screened as No.7,No.28 and No.31.5.Pot experiment were carried out to demonstrate the utilization characteristics of organic nitrogen and organic phosphorus in efficient and inefficient varieties.The results showed that the efficient cultivar No.2 of Os PAP10 c,Os PAP20,Os PAP26,Os Phy1 and Os Phy2 expression were up-regulated,the urease,acid phosphatase and phytase activities on root were increased,and the urease activity in rhizosphere soil was increased under the condition of organic fertilizer nutrition.Os PAP20 and Os Phy2 expression of efficient variety No.27 were up-regulated,the urease activity on root was increased,and acid phosphatase activity in rhizosphere soil was increased under the condition of organic fertilizer.The inefficient variety No.7 of Os PAP10 b,Os PAP26 and Os Phy1 expression were down-regulated under the condition of organic fertilizer nutrition,urease activity on root was reduced,and phytase activity in rhizosphere soil was reduced.In conclusion,the efficient organic fertilizer variety No.2 upregulated coded genes of acid phosphatase and phytase in root,increased secretion of acid phosphatase and phytase activity on root,enhanced acid phosphatase and phytase activity in rhizosphere soil,to improve organic phosphorus hydrolysis.In addition,urease activity in rhizosphere soil was increased to improve organic nitrogen utilization in rhizosphere soil.Efficient variety No.27 increased the acid phosphatase activity in the rhizosphere soil by up-regulating the expression of secreted acid phosphatase genes and phytase genes,and also increases root urease activity and the organic nitrogen and phosphate monoester status in the root system under the condition of organic fertilization application.Phosphorus capacity can improve the utilization efficiency of organic fertilizer by roots.Inefficient variety No.7 has low root urease activity,some acid phosphatase coding genes and phytase coding genes were down-regulating,and rhizosphere soil phytase activity was reduced.The ability of roots to use organic nitrogen and phytate phosphorus in organic fertilizers was reduced,and the utilization efficiency of organic fertilizers was reduced.