Whispers in the dark - do earthworms talk to plants?

蚯蚓被广泛认为对生态系统有益。它们负责许多土壤过程，产生所谓的“生态系统服务”，即生态系统为人类做和提供的事情，如食物生产和娱乐机会。人们普遍观察到，蚯蚓对生态系统的一个好处是促进植物生长。当蚯蚓在土壤中时，植物往往生长得更大、更快。随着人们对粮食安全和可持续性的担忧与日俱增，任何能够以“自然”方式提高植物生产力的东西都值得研究。蚯蚓可以通过多种机制促进植物生长。它们可能改变土壤中的微生物种群，要么增加有益微生物的数量，要么减少有害微生物的数量；蚯蚓摄取种子可能会提高发芽成功率；蚯蚓的消耗和有机物的消化可能会增加养分的有效性；挖洞活动可能会增加土壤的通气性或土壤可以容纳的水量。所有上述机制无疑在蚯蚓促进植物生长的方式中发挥了作用。蚯蚓影响植物生长的另一种不太为人所知的机制是通过产生植物生长促进激素。植物就像动物一样，对激素做出反应。土壤微生物利用这一事实来获取食物。植物根部向土壤中释放有机化合物；土壤细菌以这些化合物为食。其他土壤微生物以细菌为食，释放出帮助植物生长的营养物质。土壤微生物释放促进植物生长的激素，从而导致更多的植物生长。这种植物生长的增加导致植物将更多的有机化合物释放到土壤中，从而增加了微生物可获得的食物量。最近有研究表明，蚯蚓也可能增加土壤中植物生长促进化合物的浓度。它们这样做的原因可能与细菌相似，以增加它们可获得的食物量。蚯蚓以根部碎屑和土壤微生物为食。通过增加土壤中植物生长促进剂的水平，蚯蚓可以刺激更多植物根的产生，也可以刺激更多的土壤微生物以植物分泌的有机化合物水平的增加为食。蚯蚓如何增加植物生长促进化合物的浓度尚不清楚，这也是我们将在这个项目中寻求发现的。蚯蚓本身可以释放植物生长促进激素，这些激素可能是由蚯蚓活动促进的细菌种群产生的，或者是通过蚯蚓消化有机物而产生的。植物可能也有作用，刺激蚯蚓产生荷尔蒙。我们的研究将由一系列实验组成，在这些实验中，我们测试了各种蚯蚓-细菌-植物-土壤的存在/不存在组合，以使我们能够说明上述哪些机制是重要的。我们的结果可能有助于改变土地管理做法，以最大限度地发挥蚯蚓对植物生长的自然促进作用。

Earthworms are widely recognised as being beneficial to ecosystems. They are responsible for many of the soil processes that give rise to so called "ecosystem services", that is the things that ecosystems do and provide for humans, such as food production and recreational opportunities. One commonly observed benefit that earthworms have on ecosystems is to increase plant growth. Plants tend to grow larger and more rapidly when earthworms are in the soil. With increasing concerns about food security and sustainability anything that can increase plant productivity in a "natural" way warrants investigation. There are a number of mechanisms by which earthworms could increase plant growth. They might alter the micro-organism population in the soil, either increasing numbers of beneficial micro-organisms or reducing numbers of detrimental ones; ingestion of seeds by earthworms may increase germination success rates; earthworm consumption and digestion of organic matter may increase nutrient availability; burrowing activity may increase the aeration of the soil or the amount of water the soil can hold. All the above mechanisms undoubtedly play a part in the way that earthworms boost plant growth. Another, less well understood mechanism by which earthworms might affect plant growth is through the production of plant growth promoting hormones.Plants, just like animals, respond to hormones. Soil micro-organisms exploit this fact to get food. Plant roots release organic compounds into the soil; soil bacteria feed on these compounds. Other soil micro-organisms feed on the bacteria and this releases nutrients that help the plants to grow. The soil micro-organisms release plant growth promoting hormones which leads to more plant growth. This increase in plant growth leads to the release of more organic compounds by the plants into the soil and thus an increase in the amount of food available for micro-organisms.Recently it has been suggested that earthworms might also increase the concentration of plant growth promoting compounds in soils. They might do this for similar reasons to the bacteria, to increase the amount of food that is available to them. Earthworms feed on root debris and soil micro-organisms. By increasing levels of plant growth promoting compounds in the soil, earthworms could stimulate the production of more plant roots and also more soil micro-organisms feeding on the increased levels of plant secreted organic compounds that come from them. How earthworms increase the concentration of plant growth promoting compounds is not known and that is what we will seek to discover in this project.Earthworms could release plant growth promoting hormones themselves, the hormones could be produced by bacterial populations that are boosted by earthworm activity, or the hormones could be produced by the digestion of organic matter by earthworms. Plants may also have a role, stimulating earthworms to produce the hormones. Our study will consist of a series of experiments in which we test a variety of earthworm - bacteria - plant - soil present / absent combinations to allow us to state which of the above mechanisms are important.Our results could help lead to a change in land management practises to maximise the natural boost that earthworms give to plant growth.