Mycorrhizal development and effects on growth of the peanut (Arachis hypogaea L.)

Abstract

The association between the growth of peanut (Arachis hypogaea L.) and arbuscular mycorrhizal (AM) fungi of the genus was investigated by measurements; • mycorrhizal status of Glomus spp in diverse substrate soil conditions. • mycorrhizal dependency and nutrient uptake. • potential for mycorrhizal biocontrol of a bacterial pathogen. • mycorrhizal response to salinity stress. •effect of fungicides on Glomus mosseae mycorrhizal association. Generally these investigations indicated that both the AM fungi Glomus mosseae and Glomusfasciculatum were infective to peanuts, but displayed a differential effectiveness depending on the soil microbial biomass content in the soil. Glomus mosseae gave the best overall results in improving peanut growth and therefore it was selected for peanut mycorrhization in further experiments. There appeared to be a threshold' phosphorus requirement level for nonmycorrhizal peanuts, below which relative mycorrhizal dependency of the peanut was inclined to be significantly pronounced. Glomus mosseae protected peanut seedlings against the pathogenic bacterium Erwinia carotovora, it suppressed the pathogen population, improved the nutritional status of the plant, decreased the susceptibility of peanut seedlings to the bacterial soft rot disease and significantly alleviated disease effects. The fungus also demonstrated an ability to reduce NaCl salt stress syndrome. Glomus mosseae/peanut association in soils treated with relatively high dosages of Aspor and Plantvax fungicides was seriously affected and did not improve peanut growth substantially and appears to result in the loss of mycorrhizal benefits. This study indicates that Glomus mosseae may be a potential component to improve peanut production in low-input sustainable agrosystems.