植物根系化感物质与生物炭的相互作用及其环境效应

在我国耕地质量与面积不断下降的紧迫情况下，耕地轮作障碍成为了提高耕地使用效率的主要瓶颈，化感物质在农田系统中的积累，可能是土壤功能退化和产生生态风险的关键过程。我们假设，生物炭能通过吸附、降解、减少作物分泌等过程减少土壤系统中化感物质的含量；同时，能协助土壤微生物突破化感物质的胁迫，整体优化耕地轮作。本研究拟系统研究不同性质生物炭对植物分泌化感物质的调控，并通过模拟实验区分化感胁迫和营养竞争；用批量吸附实验研究生物炭对典型化感物质的吸附和降解，深入理解生物炭作用下的化感物质环境行为和作用范围；并在引入化感物质胁迫的特定条件中，通过对微生物群落结构和丰度的描述，评估生物炭对微生物的保护。在这些研究的基础上，尝试建立生物炭种类与化感物质或者植物类别搭配的技术方案。本研究致力于系统理解生物炭施用如何改变植物根系化感物质的分泌和迁移，为突破耕地轮作、连作障碍提供理论支持。

Because of the fast development of civilization, the land use change as well as the intensive agricultural activities, both quality and quantity of the cultivated land are decreasing greatly in recent years in our country. The main bottleneck for the high efficient utilization of cultivated land is the continuous cropping barrier. One of the major reason for this barrier is the accumulation of allelochemicals excreted by plant roots. The frequent rotation of cultivated land and the high-density cropping may stimulate crops to release more allelochemicals, even exceed the need for their own defense. These accumulated allelochemicals may have toxic effects on themselves and other crops. Understanding and controlling the excretion and environmental behavior of allelochemicals may be an important strategy to overcome the continuous cropping barrier and thus realize the efficient use of cultivated land. Because of its porous structure and abundant surface functional groups, biochar is widely used in controlling soil and water pollution. We hypothesize that biochar may reduce the content of allelochemicals in soil system through sorption, degradation, and reduction of crop secretion; at the same time, biochar can provide habitat for soil microorganisms, attenuate the stress of allelochemicals, and optimize the overall cultivated land rotation. This study intends to systematically understand the regulation of different types of biochars on crop secretion of allelochemicals. Based on lab experiments, the impact from allelochemicals stress and nutrition depletion will be distinguished. The sorption and degradation of allelochemicals by various biochars will be investigated in-depth, and thus the potential impact of biochars on the transport and effectiveness will be evaluated. Based on a detailed description of the community abundance and structure of the microbial, the sheltering of microorganisms by biochars will be studied. Based on these results, we will establish a relationship between biochar properties and allelochemical behavior, and suggest a matched application of biochars to certain crop species or allelochemical types. This study intends to illustrate how biochar applications change the secretion and mobility of allelochemicals. The result of this work will provide a core theoretical basis for a comprehensive assessment of the environmental implications of biochar, and a technical support for overcoming the obstacles of cultivated land rotation and continuous cropping.