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

A.项目摘要 有相当多的证据表明，蚯蚓可以对自然和管理的生态系统中的植物生长产生重大影响。众所周知，蚯蚓在土壤中的关键作用是：有机物质的破碎和分解，微生物活性的促进以及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远远超过它们改善土壤结构和养分供应的潜力。有非常好的研究证据表明，蚯蚓和微生物之间的相互作用可能通过各种非生育力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，其效果类似于或甚至可能包括生长素、赤霉素或细胞分裂素。如果这种可能性广泛发生，足以显著影响植物的生长，则对自然生态系统中的植物生长以及管理生态系统中的作物生产都具有重要意义，并且对土壤生物区系在整个植物生产力中的作用具有重要的生态和经济意义。 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，蚯蚓是否可以通过增加微生物活性间接影响植物生长调节剂的生产，从而显著影响植物生长，而不受其对养分有效性的影响。 该项目的重点是确定蚯蚓是否可以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，以及它们的持续时间。 该项目的三个主要目标是： 利用实验室植物生物测定法，确定土壤中是否通过蚯蚓分解有机质的活动产生影响植物生长的物质（PGI），而不是养分。 利用物理化学方法分离、表征、鉴定和定量蚯蚓分解有机质过程中产生的植物生长调节物质。 通过蚯蚓对土壤中有机质的降解，确定土壤中产生的植物生长调节剂（PGR）是否能显著影响植物生长。 该项目将试图通过实验室培养中两种微生物和两种植物有机物之间的相互作用来确认和量化PGR的产生。它还将评估两个长期田间试验的土壤中的植物生长调节剂的生产与操纵的杂草种群。 PGR的水提取物从蚯蚓培养物和蚯蚓操纵的领域土壤对蔬菜和其他植物的生长的影响将被整合。

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 .