还田麦秸酚酸物质产生、转化及生物学效应

In the southern rice-wheat rotation agro-ecosystems, amounts of straw was produced, and often adversely affected the growth of rice seedling,the reason probable mainly due to straw decomposition products. In all decomposition products, phenolic acids from wheat straw may play a major role. However, the study focusing on the production mechanism, dynamic change, biological effects and threshold of phenolic acids from wheat straw is very lacking. The project is planned using liquid chromatography/mass spectrometry(LC/MS) and high performance liquid chromatography (HPLC) technology to investigate the species of phenolic acids, the dynamic changes of major phenolic acids from wheat straw and its influencing factors. The effects of wheat straw extract and decomposing and exogenous phenolic acids on growth and development of rice seeds and seedlings would be investigated through biological methods,and experiments about the effects of phenolic acids on microbial flora, bacterial activity and soil enzyme would be carried out to assess the relationship between the straw-phenolic-rice growth. Designed to reveal the mechanism of field straw phenolic substances production, to clarify the type, quantity, and release law of phenolic acids under different field conditions. Subsequently, the relationship between the wheat straw phenolic acids and rice seedling growth could be established,which would provide a theoretical basis for the regulation of wheat straw phenolic acids in farmland ecosystem management and straw returning practice.

秸秆还田具有良好的环境与生态效应，在南方稻麦轮作区，过量小麦秸秆还田常对水稻苗期的生长发育产生不利影响，其中由麦秸产生的酚酸类物质可能起主要作用，而目前对还田麦秸酚酸类物质的产生机制、动态变化、生物学效应及作用阈值的研究十分缺乏。本项目拟采用液相色谱/质谱联用技术（LC/MS）和高效液相色谱仪（HPLC）研究还田麦秸酚酸类物质的产生种类、主要酚酸物质数量动态变化及影响因素，采用生物学测定法研究小麦秸秆浸提液和腐解物以及外源酚酸物质对水稻种子和幼苗生长发育的影响，同时研究酚酸类物质对土壤微生物区系组成、活性及土壤酶的影响，进而对秸秆-酚酸-水稻生长发育间的关系进行评估。旨在揭示还田麦秸酚酸类物质的产生机制，阐明不同还田条件下酚酸类物质的种类、数量及释放规律，初步建立小麦秸秆酚酸类物质与水稻苗期生长发育间的关系，为将小麦秸秆酚酸物质调控引入农田生态系统管理和秸秆还田实践提供理论依据。

在稻麦轮作区，过量小麦秸秆还田不利于水稻幼苗的生长发育。为全面准确评估麦秸还田对水稻生长和土壤微生态系统的影响，本研究开展了还田麦秸腐解产生酚酸等化感物质的产生机制、动态变化、生物学效应及作用阈值等系列试验；通过采用液相色谱/质谱联用技术（LC/MS）鉴定麦秸腐解产生的酚酸等化感物质，分析了主要酚酸物质数量动态变化及影响因素，并用生物学测定法评估了小麦秸秆浸提液和腐解物以及外源酚酸对水稻生长发育的影响，同时采用分子生物学方法评估了麦秸不同还田条件及酚酸物质对土壤微生物区系组成、活性的影响。结果表明：不同品种小麦以及不同土壤养分和水分供应下，麦秸中的酚酸等化感物质种类和主要酚酸物质含量显著不同，其中水分和养分供应不足，均会显著增加麦秸中酚酸物质的含量；麦秸在淹水条件下腐解产生的酚酸等化感物质种类和酚酸物质含量要多于在好氧状况时，且酚酸物质含量在14天后快速下降；土壤中酚酸的含量随着麦秸施用量的增加而增加，其中砂性土壤中的酚酸含量要高于粘土中；小麦秸秆浸提液和腐解液均会对水稻产生化感效应，且受小麦秸秆不同部位及腐解时间的影响；供试10种外源酚酸均对水稻种子的萌发产生低浓度促进、高浓度抑制作用，且与酚酸种类以及浓度有关。麦秸和酚酸物质施用均会改变土壤微生物群落细菌和真菌的结构、组成和活性。本研究初步建立起了小麦秸秆酚酸类物质与水稻苗期生长发育间的关系，有助于将小麦秸秆酚酸物质调控技术引入农田生态系统管理，进而指导秸秆还田生产实践。