Vesicular–arbuscular mycorrhizas respond to corn and soybean cropping history

Abstract

SUMMARYCommunities of vesicular-arbuscular (VA) mycorrhizal fungi were studied in a long-term crop rotation experiment at two locations (Waseca and Lamberton, Minnesota, USA). Spores of mycorrhizal fungi were counted and identified in experimental plots with a cropping history of either corn (Zea mays L.) or soybean \Glycine max (L.) Merrill], Mycorrhizal fungal communities were affected by both location and cropping history. At Waseca, Glomus aggregatum Schenck & Smith, G. leptotichum Schenck & Smith and G. occulttmi Walker spores were more abundant in soil with a corn history than a soybean history, while spores of G. microcarpum Tul. & Tul. exhibited the reciprocal pattern. Approximately 90 % of the spores recovered at Lamberton were G. aggregatum and did not vary with crop history. However, the spores of three other species: G. albidum Walker & Rhodes, G. mosseae Gerdemann & Trappe, and G. occultum, were more abundant in plots with a corn history than a soybean history. Densities of G, aggretatiim spores were negatively correlated with soil pH at Waseca, but were unrelated to pH at Lamberton were the mean soil pH was lower. Our results indicate that mycorrhizal fungal species are individualistic in their responses to cropping history and edaphic factors.

General microflora, arbuscular mycorrhizal colonization and occurrence of endophytes in the rhizosphere of two age groups of Ginkgo biloba L.of Indian Central Himalaya

“…The density of AM fungi as measured by per cent colonization and total spore count, fi rst increased with time since abandonment and then decreased in the late successional forest sites [20]. Our results on two age groups of G. biloba trees can be considered as early and late successional stages, respectively, show consistency with the above.…”

Abundance, richness and root colonization of arbuscular mycorrhizal fungi in natural and semi-natural land use types at upper Hantana

“…This was perhaps due to higher phosphorus levels in soil which could inhibit the development and colonization of AMF (Abbott and Robson, 1984). According to previous studies, AMF colonization by roots is influenced by several factors including soil properties, soil water content, plant phenology, predation and propagule availability (Anderson et al, 1984;Johnson et al, 1991;Anderson et al, 1994;Schultz et al, 2001;Muthukumar et al, 2003). Others suggested that AMF spore abundance do not always correlate with root colonization potential of AMF (Camargo-Ricalde and Dhilion 2003).…”

Negative feedback within a mutualism: host–specific growth of mycorrhizal fungi reduces plant benefit

“…Several studies have identi ed patterns consistent with negative feedback through the AM fungal community ( Johnson et al 1991;Bever 1994;Kiers et al 2000). However, in each case, accumulation of host-speci c root pathogens provides a likely alternative mechanism (Mills & Bever 1998;Bever 2002).…”