ASHS 2015 Annual Conference

Current fertility systems used in agriculture overwhelm the environment with nutrients above crop demands, which leads to water pollution and multiple environmental problems.  Biofertilizers (or microbial soil inoculants) can be used to reduce current fertilizer inputs while maintaining or improving crop plant growth and yield.  Pseudomonas putida is a plant growth promoting rhizobacteria (PGPR) and biofertilizer that is known to improve plant growth by assisting with nutrient availability, managing plant hormones, and acting as a biological control of several plant pathogens.  Therefore, a field study was conducted in 2014 at the Southern Illinois University Horticulture Research Center in Carbondale, IL, assessing the effects of application timing and dosage of two plant growth promoting rhizobacteria (PGPR) strains of P. putida [(17-29) and (G11-35)] on ‘Revolution’ bell pepper growth and yield.  Results indicated that the inoculum population denisity increased early-season vigor, plant height and caliper, and flower bud count (P < 0.0001), as well as late-season leaf SPAD values (P < 0.0001) for both strains.  Although early season fruit yield (first two harvests) increased with rhizobacteria inoculum population density (P < 0.0007 and  P < 0.0005 for total fruit weight and number, respectively), late-season fruit yields (last three harvests) were not affected.  It appears that higher early-season yields resulting from increasing rhizobacteria inoculum population densities were greater due to increased flower bud formation on more vigorous plants.