Mycorrhizal symbiosis and bioavailability of micronutrients in maize grain

Field experiments were conducted in calcareous and non-calcareous soils in order to study the biofortification of Fe and Zn in maize grain using arbuscular mycorrhizal fungal (AMF) symbiosis. Treatments consisted of two levels of FeSO4 (12.5 and 25 kg ha-1), two levels of ZnSO4 (12.5 and 25 kg ha-1) and two mycorrhizal treatments [with (M+) or without (M-)] inoculum carrying Glomus intraradices) replicated four times in a factorial RBD. The results revealed that AMF colonization significantly increased soil available Fe (M- 1.9; M+ 2.1 mg kg-1) and Zn (M- 4.16; M+ 4.50 mg kg-1). Siderophore production in M+ plants (51.4 μmol cm-3 hr) were higher than M- plants (39.5 μmol cm-3 hr) and the increase observed irrespective of levels of Fe and Zn. Increased availability of Fe and Zn in soil in combination with enhanced concentrations in plants assisted M+ plants to maintain higher micronutrient contents in grains (Fe M- 31.2, M+ 35.3; Zn M- 45.1, M+ 52.4 mg kg-1). Mycorrhizal plants produced grains with had 10- 15% higher Fe and Zn contents while anti-nutritional factor “phytic acid” had decreased (M- 1.13; M+ 1.07 mg g-1). Overall, the data suggest that mycorrhizal fungal inoculation assists in biofortification kernels with Fe and Zn besides circumventing the impact of anti-nutritional factors