Assessment of Arbuscular Mycorrhizal Fungal Inoculants for Pulse Crop Production Systems

引入市售的丛枝菌根（AMF）接种剂在豆类作物生产系统中的应用具有重要的前景。已知有效的AMF缔合可增强相对固定的营养素（如磷和各种微量营养素）的吸收，并且涉及改善的抗旱性、疾病耐受性、氮吸收和增强的生物固氮。目前，大规模释放AMF接种剂的潜在后果尚不清楚，人们认为AMF接种最好是有益的，最坏是良性的。然而，已知AMF物种促进生长的能力不同，从互利到寄生，取决于宿主植物、环境气候和土壤条件。重要的是，几乎所有市售的AMF接种物都含有根内球囊霉（Glomus intraradices）。该菌种是接种剂行业的首选，因为它易于形成孢子，适合大规模生产。一个容易产生孢子的AMF物种是否有可能取代其他天生更好的生长促进剂物种？考虑到一种持久的、积极产孢的AMF物种可能对有益的本土AMF物种和非目标宿主作物产生的潜在影响，我们必须相信，引入的物种确实是土壤微生物群落的理想补充;它是一种有效的生长促进剂;它不会取代天然存在的AMF，这些AMF本身就是更好的生长促进剂;并且对未来轮作中生长的非目标宿主作物没有负面影响。本项目的目标是：1）评估生长促进特性（包括与根瘤菌接种剂的协同作用和固氮作用）; 2）评估AMF接种对AMF种群和本地AMF定植成功的影响; 3）研究土壤和气候/天气对引入AMF的持久性的影响;（4）研究AMF接种量对促进生长和与土著AMF竞争的影响。

The introduction of commercially available arbuscular mycorrhizae (AMF) inoculants holds significant promise for use in pulse crop production systems. Effective AMF associations are known to enhance uptake of relatively immobile nutrients such as phosphorus and various micronutrients, and are implicated in improved drought resistance, disease tolerance, nitrogen uptake, and enhanced biological dinitrogen fixation. Currently, the potential consequences of large-scale release of AMF inoculants are not known, and it is assumed that AMF inoculation will be beneficial at best, or benign at worst. However, AMF species are known to differ in their ability to promote growth, ranging from mutualistic to parasitic, depending on host plant, and ambient climatic and soil conditions. Importantly, virtually all commercially available AMF inoculants contain the species Glomus intraradices. This species is preferred by the inoculant industry because it sporulates readily and is amenable to large-scale production. Does an AMF species that sporulates readily have the potential to displace other species that are inherently better growth promoters? Given the potential impact that a persistent, aggressively sporulating AMF species might have on beneficial indigenous AMF species and non-target host crops, we must be confident that the introduced species is indeed a desirable addition to the soil microbial community; that it is an effective growth promoter; that it will not displace naturally occurring AMF that are inherently better growth promoters; and there will be no negative consequences to non-target host crops grown in the future rotation. The objectives of this project are to: 1) assess the growth promotion characteristics (including synergies with rhizobial inoculants and dinitrogen fixation) of commercially available AMF inoculants as compared to indigenous AMF isolated from prairie soils; 2) assess the impact of AMF inoculation on populations and colonization success of indigenous AMF; 3) examine the impact of soil and climate/weather on the persistence of introduced AMF; and 4) examine the influence of AMF inoculant rate on growth promotion and competition with indigenous AMF.