Assessment of different carrier materials for the preparation of microbial formulations to enhance the shelf life and its efficacy on the growth of spinach (Spinacia oleracea L.).

The current study was undertaken to determine the ability of different carrier materials for sustaining the viability of microbial consortium during storage. Different bioformulations consisting of carrier material and microbial consortium were prepared and examined for viability and stability for one year stored at 4 °C and ambient temperature. Total 8 bio-formulations were prepared consisting five economically viable carriers (gluten, talc, charcoal, bentonite, broth medium) and a microbial consortium. In present study, maximum enhanced shelf-life of consortium based on colony forming unit count were recorded for talc + gluten based (B4) bioformulation (9.03 log cfu/g) over other bio-formulations stored for 360 days. Furthermore, the pot experiments was conducted to evaluate the efficacy of B4 formulation on growth of spinach in comparison with recommended dose of chemical fertilizer, uninoculated and no amendment control. The results depicted that B4 formulation increased biomass (176-666%), leaf area (33-123%), chlorophyll content (131-789%) and protein content (68.4-94.4%) of spinach over controls. Further B4 application significantly increased the nutrients like available nitrogen (131-475%), phosphorus (75-178%) and potassium (31-191%) of pot soil along with noteworthy improvement in root colonization as evident from scanning electron microscope analysis in comparison to controls at 60 days after sowing. Therefore, exploiting B4 formulation can serve as the environmentally sound approach to enhance the productivity, biomass and nutritional value of spinach. Thus, Plant growth promoting microbes-based formulation can be the novel paradigm to improve the soil health and eventually the crop productivity in economical and sustainable manner.