Abstract
High fertilizer rates are often applied to horticulture crop production systems to produce high quality crops with minimal time in production. Much of the nutrients applied in fertilizers are not taken up by the plant and are leached out of the containers during regular irrigation. The application of plant growth promoting rhizobacteria (PGPR) can increase the availability and uptake of essential nutrients by plants, thereby reducing nutrient leaching and environmental contamination. Identification of PGPR can contribute to the formulation of biostimulant products for use in commercial greenhouse production. Here, we have identified Serratia plymuthica MBSA-MJ1 as a PGPR that can promote the growth of containerized horticulture crops grown with low fertilizer inputs. MBSA-MJ1 was applied weekly as a media drench to Petunia×hybrida (petunia), Impatiens walleriana (impatiens), and Viola×wittrockiana (pansy). Plant growth, quality, and tissue nutrient concentration were evaluated 8weeks after transplant. Application of MBSA-MJ1 increased the shoot biomass of all three species and increased the flower number of impatiens. Bacteria application also increased the concentration of certain essential nutrients in the shoots of different plant species. In vitro and genomic characterization identified multiple putative mechanisms that are likely contributing to the strain’s ability to increase the availability and uptake of these nutrients by plants. This work provides insight into the interconnectedness of beneficial PGPR mechanisms and how these bacteria can be utilized as potential biostimulants for sustainable crop production with reduced chemical fertilizer inputs.
Highlights
The plant rhizosphere, the microscopic environment surrounding plant roots, hosts a diversity of microorganisms
Plants treated with MBSA-MJ1 were larger and had greener leaves than the control plants that were not treated with bacteria (Figure 1)
We determined that S. plymuthica MBSA-MJ1 can increase the growth and quality of containerized horticulture crops produced with low fertilizer inputs
Summary
The plant rhizosphere, the microscopic environment surrounding plant roots, hosts a diversity of microorganisms. The bioavailability of nutrients for plant uptake plays a significant role in plant nutrient use efficiency (NUE), and the lack of bioavailability increases the susceptibility of nutrients to leaching and runoff (Adesemoye and Kloepper, 2009; Bindraban et al, 2015). This is of particular concern for horticulture crops grown in peatbased soilless substrates, which have lower ion exchange capacities than field soil, increasing the possibility that nutrients will be removed from the substrate via leaching (Bachman and Metzger, 2008). It is important that crop producers find sustainable ways to produce crops with high yield and quality while minimizing chemical fertilizer inputs
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