Assessment of Arbuscular Mycorrhizal Fungal Inoculants for Pulse Crop Production Systems

商业上可获得的丛枝菌根(AMF)接种剂的引入在豆类作物生产系统中具有重要的应用前景。已知，有效的AMF组合可以增强对相对固定的营养物质的吸收，如磷和各种微量营养素，并有助于提高抗旱性、抗病能力、氮素吸收和增强生物脱氮固定。目前，大规模释放AMF接种剂的潜在后果尚不清楚，并假设AMF接种最好是有益的，或者是最坏的良性接种。然而，根据寄主植物、环境气候和土壤条件的不同，AMF物种在促进生长的能力方面存在差异，从互惠到寄生不等。重要的是，几乎所有商业上可用的AMF接种剂都含有IntraradicsGlomus。本种是接种剂行业的首选品种，因为它很容易萌发孢子，并且易于大规模生产。一种容易产生孢子的AMF物种有可能取代其他天生更好的生长促进剂吗？考虑到持续的、积极产孢量的AMF物种可能对有益的本土AMF物种和非目标寄主作物产生的潜在影响，我们必须相信，引进的物种确实是土壤微生物群落的理想补充；它是有效的生长促进剂；它不会取代自然发生的AMF，后者本来就是更好的生长促进剂；并且不会对未来轮作中种植的非目标寄主作物产生负面影响。本项目的目标是：1)与从草原土壤中分离的本地AMF相比，评估市售AMF接种剂的促生长特性(包括与根瘤菌接种剂的协同作用和固氮作用)；2)评估接种AMF对本地AMF种群和定植成功的影响；3)研究土壤和气候/天气对引入AMF的持久性的影响；以及4)研究AMF接种率对促进生长和与本地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.