ARS | Publication request: Plant Growth-Promoting Rhizobacteria (PGPR) in Transplant Mixes

Submitted to: International Congress of Nematology
Publication Type: Abstract Only
Publication Acceptance Date: April 20, 2008
Publication Date: December 1, 2008
Citation: Burelle, N.K. 2008. Plant Growth-Promoting Rhizobacteria (PGPR) in Transplant Mixes - Benefits for Nematode Control. International Congress of Nematology.

Technical Abstract: Many high-value crops including vegetables, melons, and strawberries are propagated from transplants. In the U.S., plug transplants are typically used for vegetables and melons, while strawberries are predominantly planted from bare-root material. However, use of strawberry plug transplants has the potential to eliminate the need for fumigation of soil in strawberry nurseries, where it has been difficult to identify alternatives to methyl bromide that do not negatively impact runner plant production. Plug transplants also allow for the introduction of biological agents such as plant growth-promoting rhizobacteria (PGPR) into the planting medium. PGPR induce systemic resistance and/or increase tolerance to pathogens in the host plant, resulting in increased plant growth and yield. In experimental field trials conducted in Florida, two Gram-positive PGPR isolates (Bacillus subtilis strain GBO3 and B. amyloliquifaciens strain IN937a) in a formulation containing chitin, reduced galling caused by Meloidogyne incognita and improved root condition of pepper (Capsicum annuum) and muskmelon (Cucumis melo) when added to transplant medium at seeding. In subsequent field trials on pepper, the population dynamics of the same PGPR strains were monitored throughout the growing season and it was determined that both PGPR strains established stable populations in the rhizosphere that persisted through harvest. Additional aqueous applications of PGPR during crop production did not increase the populations of applied strains compared to treatments only receiving bacteria in the potting medium. However, in-field applications did increase plant growth compared to the untreated control. Additional advantages of PGPR-amended plug transplants include improved stand establishment and vigor, and earlier flowering and fruit set. It has also been demonstrated that under stress, PGPR amended plug transplants produce higher yields.