Efficiency of plant growth promoting rhizobacteria in greenhouse

Plant growth promoting rhizobacteria (PGPR) play an important role in crop production by improving plant growth through various mechanisms that potentially increase sustainable agriculture. Blackberry (Rubus spp.) cultivation has acquired importance for its worldwide merchandising, including its high economic profitability, and for the health benefits in human consumption of the fruit. The quality of blackberry production depends on a good vegetative plant development; therefore, this research objective was to select strains of PGPR that stimulate vegetative growth of blackberry plants grown under greenhouse. The experiment was carried out using seedlings of the 'Tupy' blackberry, under a completely randomized design, using six rhizobacterial strains as treatments (A46, AC-35, P61, R44, BSP1.1, JLB4) and a control (no inoculated) with six replicates each. The plants were in the greenhouse for 78 d. At destructive sampling eight agronomical variables were determined. The results showed that strains A46 and P61 inoculated on blackberry plants stimulated height (45%), stem diameter (17%), leaf area (110%), and shoot DM (150%). Inoculation of strain A46 on blackberry plants increased nutrient extraction of N, P, K, Ca, Mg, S, B, Cu, Fe, Mn, and Zn. Pseudomonas tolaasii strains P61 and A46 stimulated growth and nutrient extraction in blackberry plants, and these will be selected to inoculate the blackberry crop for production under greenhouse conditions. Key words: Biomass, nutrient extraction, rhizobacteria, Rubus spp., vegetative development.