Selective interactions between different species of mycorrhizal fungi and Rhizobium meliloti strains, and their effects on growth, N₂‐fixation (¹⁵N) and nutrition of Medicago sativa L.

Abstract

SUMMARYThree isolates of vesicular-arbuscular (VA) mycorrhizal fungi, belonging to the species Glomus mosseae (Nicol. and Gerd.) Gerd. and Trappe, G. fasciculatum (Taxter sensu Gerd.) Gerd. and Trappe, and G. caledonium (Nicol. and Gerd.) Trappe and Gerd, were inoculated in dual combinations with six strains oi Rhizobium meliloti with the aim of testing these combinations for functional compatibility with their common host plant, the legume Medicago sativa L. Symbiotic efficiency (promotion of plant growth and N and P nutrition) was found to be dependent on the particular combination of Rhizobium strain and Glomus species indicating selective and specific compatibilities between strains and isolates of the two types of microsymbiont, but also between them and the common host plant. Observed effects on plant growth were in general, though not always, related to the extent of VA mycorrhizal colonization. Although the different mycorrhizal and/or rhizobial treatments produced different effects on plant growth, the rate of nodule formation on M. sativa roots remained constant. Most mycorrhizal treatments increased the concentration and/or content of N in plant shoots but effectiveness was in the order: G. fasciculatum > G. mosseae > G. caledonium. In some cases, this increase in N-content may be a consequence of a P-mediated stimulation of Nj-fixation by VA mycorrhiza, as ascertained using ^''N. In other instances, however, the increase seems to reflect a VA mycorrhizal-mediated enhancement of N-uptake from soil. VA mycorrhizal inoculation decreased the concentration of Ca and Mg in plant shoots and a buffering effect of VA mycorrhiza in situations of nutrient excess in soil is proposed.

Arbuscular mycorrhizal fungi and mycorrhizal stimulant affect dry matter and nutrient accumulation in bean and soybean plants1

“…The bacteria, in turn, increase the N content, by means of biological fixation of atmospheric N 2 , and the arbuscular mycorrhizal fungi contribute primarily to P intake. However, the simultaneous presence of symbionts may result in synergistic, neutral or even antagonistic effects for the development of the host plant, depending on the bacteria and arbuscular mycorrhizal fungi species (Azcón et al 1991, Ahmad 1995, Xavier & Germida 2002, Silva et al 2016.…”

Interactions between plant‐growth‐promoting rhizobacteria (PGPR), arbuscular mycorrhizal fungi and Rhizobium spp. in the rhizosphere of Anthyllis cytisoides, a model legume for revegetation in mediterranean semi‐arid ecosystems

“…In this context, the role of the AM fungi as P suppliers to the plant, and particularly to the nodule, appears to be of great relevance. Because mycorrhizal status benefits the uptake of immobile ions, the symbiotic N., fixation results were favoured by the increased P content in plant tissues (Barea & Azcon-Aguilar, 1983;Barea, Azcon-AgLiilar & Azcon, 1987;Azcon, Rubio & Barea, 1991). Some other non-P-mediated effects might also be involved (Ames & Bethlenfalvay, 1987;Johansen et al, 1993).…”

Crop rotation biomass and arbuscular mycorrhizal fungi effects on sugarcane yield

“…These fungi are present in over 80% of plant species (Azcón et al, 1991). In contrast with the large diversity of plants, which includes sugarcane, that have their roots colonized by mycorrhizas, only 150 fungi species are responsible for that colonization (Azcón et al, 1991).…”

“…These fungi are present in over 80% of plant species (Azcón et al, 1991). In contrast with the large diversity of plants, which includes sugarcane, that have their roots colonized by mycorrhizas, only 150 fungi species are responsible for that colonization (Azcón et al, 1991). A crop whose roots are colonized by mycorrhizal fungi can raise the soil mycorrhizal potential which can benefit plants which are responsive to this fungi association and that are cultivated in sequence.…”