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Iron (Fe) deficiency is a universal phenomenon restricting plant production and soil microbes, which can be observed mostly in semi-arid regions. Inoculation of mycorrhizal fungus (Glomusmosseae) with a foliar spray of Fe in arid soil could improve soil quality and plant biomass, resulting in a better eggplants yield. However, it remains uncertain how such an association increases soil quality, nutrients content and plant production in arid lands. We tested the effect of four treatments (control C, mycorrhiza M, foliar spray of F F, and mycorrhizae + foliar spray of Fe M+F) respectively on soil respiration, soil microbial biomass (SMB), the metabolic quotient (qCO2), infection rate, nutrients content, roots weight and eggplant (Solanum melongena L.) yield in arid agricultural soils of Iraq. Overall, M showed the highest values in soil respiration (233.20 CO2-C mg g-1), infection rate (72%), SMBC (107.58 µg C g-1 soil) and microbial quotient (8.52 µg C g-1 soil- g C /kg soil). Nevertheless, F neither changed significantly (p<0.05) phosphorus content and MBC nor chlorophyll rate over control. More specifically, the fruit yield was closely associated with the infection rate, qCO2, microbial biomass, roots weight, nitrogen and phosphorous contents but not to iron content. These novel results indicated that chelated iron application alone had no uniform positive effects on most MBC and phosphor content while the combination of a mycorrhizal fungus with chelated iron was more effective in enhancing soil microbes and plant yield in arid agricultural lands.

Mycorrhizae, MBC, qCO2, microbial respiration, foliar spray of Fe, eggplant.

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