Effect of rhizobacteria (PGPR) and growing medium on the productive and nutraceutical quality of blackberry (Rubus spp.)

ABSTRACT The growing demand and consumption of blackberry (Rubus spp.) fruits is based on their nutraceutical quality. One option for achieving sustainable production is the use of plant growth-promoting rhizobacteria (PGPR). The productive and nutraceutical quality of blackberry is linked to its management and nutrition during its development. Therefore, the objective of this research was to evaluate the effect of PGPR strains of the genus Pseudomonas on different growing medium on the productive and nutraceutical quality of blackberry under greenhouse conditions. The experiment established rhizomes with roots of the ‘Tupy’ blackberry, under a completely randomized design with a factorial arrangement (2 × 3). The factors were the growing medium (tezontle, soil) and PGPR strains (without PGPR, P61, A46) with six replicates each. Defoliation was performed 192 d after transplantation. During fruiting, morphological and nutraceutical variables were determined in fruits, and foliar nutritional analysis. According to the results, strain A46 stimulated the length (4%) and fruit diameter (10%), foliar concentrations of S and Fe and the nutraceutical variables are exploratory for further research with this strain, while strain P61 increased foliar concentrations of N (58%) and Mo (51%). The use of tezontle improved foliar concentrations of S, and in soil, increased fruit size, and foliar concentrations of N, Fe and Mo. Therefore, the productive quality of blackberry under greenhouse conditions, could be optimized by inoculation the A46 strain in soil as a growing medium.