Effect On Soil Microbial Community Structure And Rice Growth In Different Rice Paddy-upland Rotation Cropping System

Rice paddy-upland rotation cropping system has been widely used in southern rice growing regions of China.This cropping system can prompt sustainable development of farmland by improving land use efficiency,soil ecological environment and rice yield.The irrigation after rice transplanting caused dry farmland soil changed to full of water,soil environmental have dramatic changes in this process.In the process the soil water content,oxygen aeration condition and the soil redox status occurred great changes.Therefore,it has significant influence on soil nutrient and material cycling,ultimately affect the growth and development of rice.Reasonable paddy upland rotation mode can improve the ecological environment of soil,achieve more efficient utilization of soil nutrients,improve the structure of the soil,provide theoretical support for the paddy productive and sustainable development.Three kinds of crop rotation in rice fields,including potato with straw mulching under zero-tillage(PR),rape direct seeding under zero-tillage(RRPR),paddy winter leisure(ILR),the potatoes-maize rotation(PC)and five common paddy upland rotation modes including potatoes-rice(PR),rapeseed-rice(RR),garlic-rice(GR),wheat-rice(WR)and broad beans-rice(BR)were designed to study the changes in the structure of the soil microbial community,the soil enzyme activities,in rice growth and development and paddy field on rice yield.The main results were as follows:1.Through setting the field test and the combination of high throughput sequencing field test methods under different paddy upland rotation modes the rice soil microbial community structure changes,the result shows that: the changes in the structure of the soil microbial community under different paddy upland rotation modes vary differently in the main growth period of rice.But the soil under different paddy upland rotation modes all contain the same high level of ten door bacteria.The main advantage bacterium groups in the soil are Proteobacteria,Acidobacteria,Bacteroidetes and Chloroflexi.In the whole fertility period of rice,there was no significant difference in the soil microbial community diversity under different paddy upland rotation modes.Compared with paddy winter leisure,crop rotation modes not only improved the soil microbial diversity and change the advantage bacterium group in the soil microbial community.In the soil of paddy upland rotation modes,the highest relative abundance of the door in bacterial community composition is Proteobacteria.However,the highest relative abundance of the door in bacterial community composition in paddy winter leisure soil is Bacteroidetes.2.Catalase and Urease activity dynamic changes are different in the soil under different paddy upland rotation modes,and surface soil enzyme activities are higher than the lower soil enzyme activities.At the early stage of the rice growth and development,paddy soil enzyme activities in changing with the transplanting days tend to be consistent.Catalase activity presented rising at the beginning and declining then rising again.Urease activity presented reducing at the beginning and rising then reducing again.The Catalase activity in PR,BR and GR is higher than the Catalase activity in RR and WR.The activity of two enzymes in different rotation patterns and different rotation types in 2016 increased from the soil enzyme activity in 2015.3.Five paddy upland rotation modes have different effect on rice plant height and tillers,but rice plant height and tillers under paddy upland rotation modes change with the days number of transplanting have the same rule.Rice plant height,tillers,dry matter weight of single stem,groups of dry matter,after heading material assimilation and harvest index all are the highest in PR,GR and WR is the lowest mode.Compared with paddy winter leisure,crop rotation modes can significantly promote the growth and development of rice,the specific performance is:PR>RRPR>ILR.4.There are obvious differences in rice yield under different paddy upland rotation modes,PR,GR,BR are significantly higher than WR,RR.There paddy upland rotation modes could increase yield by increasing the effective panicles and spike grain number.Compared with paddy winter leisure,crop rotation modes can significantly increase yield.Compared with ILR,the yield in PRand RRPR was improved by 6.3% and 2.8%.