The Production of Plant Growth Regulators in Soil through Interactions between Earthworms, Microorganisms and Organic Materials

A.项目概述有相当多的证据表明，蚯蚓可以对自然和人工管理的生态系统中的植物生长产生重大影响。蚯蚓在土壤中的主要作用是：有机质的破碎和分解、微生物活动的促进和植物养分的释放和转化。然而，蚯蚓对改善植物生长的贡献往往大大超过它们改善土壤结构和养分有效性的潜力。有很好的研究证据表明，蚯蚓和微生物之间的相互作用可能通过各种非生殖介导的生物因素影响植物生长，例如，通过产生促进植物生长的物质，其作用类似于甚至可能包括生长素、赤霉素或细胞分裂素。这种可能性，如果广泛发生，足以显著影响植物的生长，具有重要的意义，植物的生长。自然生态系统以及管理生态系统中的作物生产，并将对土壤生物群在整个植物生产力中的作用产生重要的生态和经济影响。在过去的2-3年中，越来越清楚地表明，土壤微生物可以产生大量的植物生长调节剂（pgr）。这就提出了一个问题，即蚯蚓是否可以通过增加微生物活动间接影响pgr的产生，从而显著影响植物生长，而不依赖于它们对养分供应的影响。这个项目的重点是确定蚯蚓是否能够刺激土壤中植物生长调节物质的整体生产，它们采取什么形式，它们的数量是否足以显著影响植物生长，以及它们持续多久。本项目的三个主要目标是：利用实验室植物生物测定法，确定除营养物外，影响植物生长的物质是否通过土壤中蚯蚓的活动在有机物分解中产生。利用理化方法分离、表征、鉴定和定量研究蚯蚓在有机物分解过程中产生的植物生长调节化合物（pgr）。通过蚯蚓在有机物分解中的活动，确定土壤中产生的植物生长调节剂（pgr）是否会显著影响植物的生长。该项目将试图通过两种蚯蚓和微生物在实验室培养的两种植物有机物质上的相互作用来确认和量化pgr的产生。它还将评估对蚯蚓种群进行的两个长期田间试验土壤中pgr的产生情况。将整合蚯蚓培养物和蚯蚓处理土壤水提取物中PGR对蔬菜和其他植物生长的影响。

A. PROJECT SUMMARY There is considerable evidence that earthworms can have major influences on the growth of plants in natural and managed ecosystems. It is well-established that the key roles of earthworms in soils are: the fragmentation and decomposition of organic matter, the promotion of microbial activity and the release and transformation of plant nutrients. However, the contributions of earthworms to improvements in plant growth often greatly exceed the potential that they have to improve soil structure and nutrient availability. There is very good research evidence that interactions between earthworms and microorganisms may influence plant growth through various biological factors that are not fertility-mediated, e.g. by producing substances that promote plant growth similar in effect to or even possibly including auxins, gibberellins or cytokinins. Such a possibility, if occurring widely enough to affect the growth of plants significantly, has important implications for both the growth of plants in .natural ecosystems as well as crop production in managed ecosystems, and would have-important ecological and economic implications for the role of the soil biota in overall plant productivity. During the last 2-3 years it has become increasingly clearly demonstrated that soil microorganisms can produce significant amounts of plant growth regulators (PGRs). This raises the question whether earthworms can influence the production of PGRs indirectly, through increasing microbial activity and as a consequence affect plant growth significantly, independent of their infiuences on nutrient availability. This project focuses on establishing whether earthworms can stimulate the overall production of plant growth-regulating substances in soil, what form they take, whether they occur in amounts sufficient to influence plant growth significantly, and how long they persistS. The three main objectives in this project are: To determine, using laboratory plant bioassays, whether plant grow th-influencing substances (PGIs), other than nutrients, are produced through in the soil through the activities of earthworms in organic matter breakdown. To isolate, characterize, identify and quantify, using physico-chemical methods, some specific plant growth-regulating compounds (PGRs) produced through the activities of earthworms in organic matter breakdown. To determine whether plant growth can be influenced significantly by plant growth regulators (PGRs) produced in the soil through the activities of earthworms in organic matter breakdown. The project will attempt to confirm and quantify the production of PGRs by interactions between two species of earthworm and microorganisms on two kinds of plant organic matter in laboratory cultures. It will also assess the production of PGRs in the soils of two long-term field experiments with manipulated earthworm populations. The influence of PGR's in aqueous extracts from earthworm cultures and from earthworm-manipulated field soils on growth of vegetables and other plants will be integrated .