Isolation of growth-promoting bacteria from the rhizosphere of guava plants (Psidium guajava)

Abstract

The guava production for 2008 in the state of Guanajuato was 177 hectares of planted area and the same number of harvested area, production of 1,130.80 tons. In traditional agricultural practices, excessive use of mineral fertilizers has been made, which, although it is true, guarantee a good production, are expensive and cause imbalances in the agroecosystems by contaminating the soil, water, and food. In this work, the effect of Bacillus subtilis strains as a promoter of plant growth in guava plants in greenhouse conditions was evaluated. Three strains were used, and they were inoculated in a pot with the guava plant. The height, number of branches and leaves were measured. Soil samples were taken from 2 guava orchards for the isolation and characterization of rhizobacteria. A selective medium with 1-carboxylic acid, -1- aminocyclopropane was used and bacteria with ACC deaminase activity were selected. The isolates were determined to be resistant to antibiotics, confronted with phytopathogenic fungi, in vitro plant growth tests and BIOLOG metabolic profiles. 30 isolates with ACC activities were found, 7 had a biological control effect and 5 had an effect on root development in vitro. The use of growth-promoting rhizobacteria is an excellent alternative to improve guava production, a crop for which very little is known about the microflora associated with its rhizosphere and the ecological role they play in the soil.