JWSS - Journal of Water and Soil Science

Arbuscular mycorrhizal fungi (AMF) are widespread endosymbionts in terrestrial ecosystems and their exudates have important effects on soil properties. A greenhouse experiment was conducted with six AMF treatments including four exotic species inoculums (Funneliformis mosseae ,Claroideoglomus claroideum  and Rhizophagus irregularis and a mixed isolate of three species), one mixed native AMF species treatment and a sterilized soil (control) with four salinity levels (1, 5, 10 and 15 dS m^-1). AMF increased the soil (EEG) and total (TG) extractable glomalin, and also the hot water (HWC) and diluted acid (DAC) extractable carbohydrates compared to control treatment in all salinity levels. The native AMF species had the greatest effects on EEG, TG, HWC and DAC at 10 and 15 dS m^-1. Soil EEG and TG concentrations were higher in the mixed exotic AMF treatment than in each AMF species. The greatest glomalin concentration was related to F. mosseae at 1, 5 and 15 dS m^-1 but at 10 dS m^-1 the greatest glomalin concentration was related to C. claroideum. The greatest carbohydrate concentration was related to F. mosseae at 1 and 5 dS m^-1 but at 15 dS m^-1 significant differences were observed among the three AMF species. Our results showed that there is an interaction between salinity and different AMF species, and a combination of them determines the function of AMF.

Glomalin is a glycoprotein identified in and extracted from cell walls of hyphae and spores of Glomeral fungi. It deposites on soil particles and acts as a glue which leads to the formation and stabilization of soil aggregates. Water deficit stress by affecting mycorrizal symbiosis can alter glomalin production. This study was conducted as a factorial experiment arranged in a completely randomized design (CRD) with four replications using corn (Zea mays L. Single cross 704) under greenhouse conditions. The first factor was three levels of soil moisture including 10-30% (W₀), 35-55% (W₁), 60-90% depletion of available water (W₂) and the second factor was three species of mycorrhizal fungi, Glomus versiforme (Gv), Glomus intraradices (Gi), Glomus etunicatum (Ge) and non mycorrhizal control (NM). At the end of vegetative growth, easily extractable glomalin (EEG) and total glomalin (TG) were measured using the Bradford method after extraction from soil. Shoot and root dry weights and root colonization decreased by declining soil moisture level. Water deficit significantly increased the amount of EEG and TG in soil. Also, a significant increase in glomalin production was observed at W₂ level in all three fungal species compared to the W₀ and W₁ moisture levels. Moreover, by enhancing water deficit stress and decreasing root colonization, glomalin production per unit percent of root colonization was significantly increased.