U.S. Department of Agriculture, Agricultural Research Service, North Central Agricultural Research Laboratory, 2923 Medary Ave, Brookings, SD, 57006, USA.
TerraNimbus, LLC, 5326 GA Highway 93, Pelham, GA, 31779, USA.
Mycorrhiza. 2019 May;29(3):227-235. doi: 10.1007/s00572-019-00884-4. Epub 2019 Mar 13.
Arbuscular mycorrhizal (AM) fungi are considered to be a key group of soil organisms for assessments of soil biological properties and developing relationships among crop production management practices, soil properties, crop performance, and ecosystem services. In a field study of cover crop treatments established during the transition from small grains to corn (Zea mays L), we assessed multiple measures of AM fungal responses to the management treatments: soil propagule numbers, biomass via lipid biomarkers, and root colonization extent. Our objectives were to determine response variables that reliably distinguished cover crop treatments and formed consistent relationships with grain yield, plant biomass, and mineral nutrient concentrations of the following corn crop. The number of soil AM fungal propagules and amount of the NLFA biomarker C16:1cis11 measured on fall-collected soils most consistently and significantly responded to fall cover crop treatments. Neither of these measures of soil inoculum potential was strongly related to measures of crop performance. The PLFA biomarker C16:1cis11 was marginally responsive to cover crop but did not strongly relate to crop performance parameters. Corn root colonization by AM fungi was not significantly affected by cover crop treatment, but significant negative relationships were found between root colonization and grain N concentration and plant biomass at maturity. In contrast, a significant positive relationship between root colonization and plant N concentration at the 6-leaf stage was found. Understanding the relative effectiveness and limitations of AM fungal response variables will inform their application in field studies of agricultural management practices.
丛枝菌根（AM）真菌被认为是评估土壤生物特性的关键土壤生物类群之一，有助于建立作物生产管理实践、土壤特性、作物表现和生态系统服务之间的关系。在从小麦向玉米（Zea mays L.）过渡期间建立覆盖作物处理的田间研究中，我们评估了 AM 真菌对管理处理的多种反应措施：土壤繁殖体数量、通过脂质生物标志物测量的生物量以及根系定植程度。我们的目标是确定能够可靠区分覆盖作物处理并与以下玉米作物的谷物产量、植物生物量和矿物养分浓度形成一致关系的响应变量。秋季采集的土壤中 AM 真菌繁殖体数量和 NLFA 生物标志物 C16:1cis11 的数量最能可靠地响应秋季覆盖作物处理，且变化幅度最大。这两种土壤接种潜力的测量指标都与作物表现的测量指标没有很强的关系。PLFA 生物标志物 C16:1cis11 对覆盖作物有一定的响应，但与作物性能参数没有很强的关系。玉米根系被 AM 真菌定植的情况不受覆盖作物处理的显著影响，但在成熟时与根系定植和谷物氮浓度以及植物生物量呈显著负相关。相比之下，在 6 叶期发现了根系定植与植物氮浓度之间存在显著的正相关关系。了解 AM 真菌反应变量的相对有效性和局限性将为其在农业管理实践的田间研究中的应用提供信息。
