Algoma University, Sault Ste. Marie, Ontario, Canada.
Department of Forestry, Michigan State University, East Lansing, Michigan, USA.
Ecol Appl. 2022 Mar;32(2):e2501. doi: 10.1002/eap.2501. Epub 2022 Feb 6.
Plant-soil feedback (PSF) can be a major driver of plant performance in communities, and this concept can be used in selecting crop rotation sequences to maximize agricultural yields. Potential benefits of using PSF in this context include nutrient use optimization, pathogen reduction, and enhancement of mutualisms between crops and microbes. Yet the contributions of these combined mechanisms are poorly understood. Here we investigated the relative contributions of these mechanisms using five major crops commonly cultivated in rotation (alfalfa, canola, maize, soybean, and wheat) under controlled conditions. We trained soil by growing each of the five crops in a "training phase," and then reciprocally planted the five crops in the trained soils in a "feedback phase." To tease out soil biota from nutrient effects, we established three treatments: "control" (trained unsterilized soil used in the feedback phases), "biota" (sterilized soil in the feedback phase inoculated with soil biota from the control treatment after the training phase), and "nutrient" (sterilized soils in both phases). Plant-soil feedback for each crop was calculated by comparing the total biomass of each crop grown in soils trained by each of the four other crops (i.e., in rotation) against total biomass in self-trained soil (i.e., monocropping). We found that PSF values varied among crop combinations in all the treatments, but such variation was the greatest in the nutrient treatment. Overall, soil biota feedback tended to be lower, whereas nutrient feedback tended to be greater compared to the unsterilized control soil, suggesting that effects of antagonistic biota outweighed those of beneficial microbes in the biota treatment, and that plants optimized nutrient uptake when the soil microbiome was absent in the nutrient treatment. Furthermore, soils in the nutrient treatment trained by the legume crops (alfalfa and soybean) tended to provide the greatest positive feedback, emphasizing the important legacy of N fixers in crop rotation. Taken together, our data demonstrate how nutrients and soil biota can be integral to PSFs among crops, and that assessing PSFs under controlled conditions can serve as a basis to determine the most productive crop rotation sequences prior to field testing.
植物-土壤反馈（PSF）可以是群落中植物表现的主要驱动因素，这一概念可用于选择作物轮作序列以最大化农业产量。在这种情况下，利用 PSF 的潜在好处包括优化养分利用、减少病原体和增强作物与微生物之间的互利共生。然而，这些综合机制的贡献还知之甚少。在这里，我们在控制条件下，使用五种常见的轮作作物（紫花苜蓿、油菜、玉米、大豆和小麦）来研究这些机制的相对贡献。我们在“训练阶段”中种植每一种作物来训练土壤，然后在“反馈阶段”中在经过训练的土壤中反向种植这五种作物。为了从养分效应中分离出土壤生物群，我们建立了三种处理方法：“对照”（在反馈阶段中使用未经灭菌的土壤）、“生物群”（在反馈阶段中用来自对照处理的土壤生物群接种灭菌土壤，然后在训练阶段之后）和“养分”（在两个阶段中都使用灭菌土壤）。通过比较每种作物在由其他四种作物（即轮作）中的每一种作物训练的土壤中生长的总生物量与在自我训练的土壤（即单作）中的总生物量，计算出每种作物的 PSF 值。我们发现，在所有处理中，作物组合之间的 PSF 值存在差异，但在养分处理中差异最大。总的来说，与未灭菌的对照土壤相比，土壤生物群反馈往往较低，而养分反馈往往较高，这表明拮抗生物群的影响大于生物群处理中有益微生物的影响，并且当养分处理中不存在土壤微生物组时，植物优化了养分吸收。此外，在养分处理中，由豆科作物（紫花苜蓿和大豆）训练的土壤往往提供最大的正反馈，这强调了固氮菌在作物轮作中的重要作用。总之，我们的数据表明，养分和土壤生物群如何成为作物之间 PSF 的组成部分，并且在受控条件下评估 PSF 可以作为在田间试验之前确定最具生产力的作物轮作序列的基础。
