Evaluación de Bacillus y Pseudomonas para colonizar la rizosfera y su efecto en la promoción del crecimiento en tomate (Physalis ixocarpa Brot. ex Horm.)

Abstract

One of the main characteristics that plant growth-promoting rhizobacteria (PGPR) must have is good rhizosphere colonization. This study evaluates the ability of five PGPR separately and together (Bacillus-Pseudomonas), including four strains of Pseudomonas fluorescens (UM16, UM240, UM256 and UM270) and one of Bacillus thuringiensis (UM96), to colonize the rhizosphere of maize (Zea mays L.) plants. Additionally, the promoting effect of the bacterial consortium on green tomato (Physalis ixocarpa Brot. ex Horm.) seedlings was assessed. The results showed that the five strains analyzed are highly competent to colonize the rhizosphere, in addition to not presenting antagonism in vitro between them. The recovered strains were analyzed by means of their natural resistance to carbenicillin and by means of random amplified polymorphic DNA. Also, by assessing the growth-promoting effect of inoculating the strains together, only the combination of B. thuringiensis UM96 and P. fluorescens UM16 significantly improved the total fresh weight of the tomato seedlings and increased hypocotyl and root length. The P. fluorescens strains, separately, were the only ones that showed a beneficial effect on seedling development. The results showed that only the UM96-UM16 consortium had beneficial interaction with the plant, while separately the strains showed broad potential for colonizing the rhizosphere and promoting tomato plant growth.