Application of Microbial Inoculants Promote Plant Growth, Increased Nutrient Uptake and Improve Root Morphology of Corn Plants.

Reducing fertilizers impacts from agriculture is a world-wide concern, both from an environmental and human health perspective.  One way to reduce impacts of fertilizers is by enhancing plant uptake which improves nutrient use efficiency and also potentially reduce the amounts of fertilizer needed. Adding microbial inoculants with standard or reduced applications of inorganic fertilizers has recently been shown to improve fertilizer use efficiency. The objective of the present study was to test, at the greenhouse level, the effects of microbial inoculants on corn nutrient uptake, under different N fertilizer treatments and at different stages of corn growth. Treatments consisted of SoilBuilder (SB) from Agricen Science, a metabolite extract of SoilBuilder (SBF), and a mixture of PGPR bacilli (BM).  Experiments included three nitrogen fertilizers: urea, urea ammonium nitrate 32% N (UAN), and calcium ammonium nitrate 17% N (CAN) and an un-fertilized control. Plant growth parameters were taken at V2, V4, V6, and VT stages. Plant tissue analysis was performed at V4, V6 and VT stages, and root morphology analysis was performed at V2 and V4 stages. Plant growth parameters (height, shoot fresh and dry weight) were increased in plants treated with microbial inoculants and the differences were greater in plants evaluated at VT stage. Plant nutrient uptake (N, P, and K) was increased by microbial inoculants starting at the V4 stage, but more significant differences occurred at VT stage. Total root length, root volume, and root surface were increased at the V2 and V4 stages in plants with microbial inoculants.  The effect of microbial inoculants depends on the type of nitrogen fertilizer applied, and also depends on the stage in which the plant was evaluated.  Overall, the results demonstrate that microbial inoculants can increase nutrient uptake, enhance plant growth, and improve root morphology.