Cyanobacteria-based bioinoculants influence growth and yields by modulating the microbial communities favourably in the rhizospheres of maize hybrids

Abstract

Interactions between ten maize hybrids (Prakash, HM4, HM8, HM9, HQPM1, HQPM5, PEHM7, PEHM3, PEHM5 and VH27) and five cyanobacteria based inoculants, along with uninoculated control, were evaluated for identifying the promising combinations for improved soil microbial activities and crop production. The rhizosphere soil samples analyzed at mid-crop stage revealed significant interactive effects of hybrids and inoculants on the concentrations of glomalin and polysaccharides and dehydrogenase activity. Acetylene reduction (assayed as an estimate of nitrogenase activity) was three folds higher in the inoculated treatments. In the phospholipid fatty acid based analysis of selected rhizosphere soils, the concentrations of total PLFAs were found to range from 163 to 398 nmol g−1 soil with lowest at H1B1 (control) and highest at H5B2 (HQPM1 inoculated with Anabaena + Nostoc consortium). The principal component analysis suggested that H1B1 (control) and H4B2 (HM9 inoculated with Anabaena -Nostoc consortium) shared common characteristics of community profiles with higher abundance of AM fungi and Eukaryotes. Among the inoculants, Anabaena-Azotobacter, Anabaena-Trichoderma biofilms, and the Anabaena + Providencia consortium were identified as the most promising for all the hybrids tested, while the combination of hybrid Parkash and Anabaena-Trichoderma biofilm was superior to other combinations, exhibiting highest values for both crop and microbiological parameters. Maize plant height, was positively influenced by the cyanobacteria-based formulations, though the cob yields were statistically at par with control (no inoculation), albeit with 20–30% increases in all inoculated treatments. These analyses suggest the promise of these bioinoculants as plant growth promoting options in the integrated nutrient management strategies for maize hybrids.