Interactions of microbial inoculants with soil and plant attributes for enhancing Fe and Zn biofortification in maize genotypes

Abstract This study aims to improve the iron and zinc mobilization from soil to maize kernels using cyanobacteria-based formulations. Towards this, focused analyses of plant physiological attributes, nutrient availability in soil and its enrichment in the kernels of maize hybrid, Pusa Vivek QPM 9 Improved (G1) and its parental inbreds Pusa Maize Inbred Provitamin 1 (G2) and Pusa Maize Inbred Provitamin 2 (G3) was undertaken. The treatments included formulations of individual agriculturally beneficial organisms-a cyanobacterium- Anabaena torulosa, fungus-Trichoderma viride, and a bacterium Providencia sp. and their laboratory-developed biofilms - A. torulosa – Trichoderma viride (An-Tr) and A. torulosa – Providencia sp. (An-PW5). Application of An-Tr biofilm formulation led to 14- and 3.3-fold increase in nitrogenase activity and chlorophyll of soil respectively, over control, at the seedling stage. Hybrid (G1) recorded a significant increase of 1.2–1.5-fold in terms of nitrogenase activity over the parent genotypes. The highest zinc content in maize kernels, with a 1.34-fold increase over control, was recorded with An-Tr biofilm treatment, while T. viride increased kernel Fe content by 2.1-fold. Multivariate analyses illustrated a significant correlation of soil biological parameters-nitrogenase activity, chlorophyll, polysaccharides, Fe, Zn, with kernel Fe and Zn content in maize genotypes. Linear discriminant analyses validated the significant effects of individual microbial inoculation and biofilms. An-Tr biofilm- G1 (hybrid) combination can be a model system for in-depth analyses of beneficial effects of microbe-mediated biofortification of maize, leading to improved kernel quality and 25 % N savings.