Mycorrhizal (Rhizophagus Intraradices) Symbiosis and Fe and Zn Availability in Calcareous Soil

ABSTRACT

Greenhouse experiment was conducted to assess the iron (Fe) and zinc (Zn) fractionation patterns in soils of arbuscular mycorrhizal (AM) fungus-inoculated and uninoculated maize plants fertilized with varying levels of Fe and Zn. Soil samples were collected for Fe and Zn fractions and available Fe, Zn and phosphorus (P) contents besides organic and biomass carbon (BMC), soil enzymes and glomalin. Major portion of Fe and Zn fractionations was found to occur in the residual form. Mycorrhizal symbiosis increased the organically bound forms of Fe and Zn while reducing the crystalline oxide, residual Fe and Zn fractions, indicating the transformation of unavailable forms into available forms. Soil enzymes, viz. dehydrogenase and acid phosphatase activities in M+ soils, were significantly higher than M− soil consistently. Overall, the data suggest that mycorrhizal symbiosis enhanced the availability of Fe and Zn as a result of preferential fractionation and biochemical changes that may alleviate micronutrient deficiencies in calcareous soil.

Abbreviations: AM: arbuscular mycorrhiza; Fe: Iron; Zn: Zinc; P: Phosphorous; Amox-Zn: amorphous oxide bound zinc; Cryox-Zn: crystalline oxide bound zinc; DAS: days after sowing; DTPA: diethylene Triamine Penta Acetic Acid; MnO₂-Zn: manganese oxide bound zinc; OC-Zn: organically bound zinc; WSEX: water soluble plus exchangeable zinc; MnO₂ Fe: manganese oxide bound iron; OC-Fe: Organically bound iron; WSEX Fe: water soluble plus exchangeable iron.

KEYWORDS:

• Iron
• maize
• micronutrients
• mycorrhiza
• soil enzymes
• zinc

Funding

The authors are thankful to the Indian Council of Agricultural Research (ICAR) for providing financial support to the Principal Investigator of the Scheme Dr. K.S. Subramanian under the AMAAS (Application of Microorganisms in Agriculture and Allied Sector) for the past 5 years during the period 2006–2014.

Additional information

Funding

The authors are thankful to the Indian Council of Agricultural Research (ICAR) for providing financial support to the Principal Investigator of the Scheme Dr. K.S. Subramanian under the AMAAS (Application of Microorganisms in Agriculture and Allied Sector) for the past 5 years during the period 2006–2014.