Plant Growth-Promoting Rhizobacteria in Bean Production

Attempts to produce food of plant origin without the use of fertilizers and pesticides are progressively becoming more numerous. It was also found that microorganisms have the ability to provide plants with necessary nutrients. Biofertilizers are expected to take an important place in agricultural production in the years to come. To produce quality biofertilizer, it is necessary to thoroughly study the microorganisms, their relationships, and relationships between organisms and crops for which the biofertilizer is intended. In the present study, we observed the effect of bean treatment with rhizobacteria on the soil microbial status and bean development and yield. A trial was established at Institute of Field and Vegetable Crops, Novi Sad. The inoculants came from the Faculty of Agriculture, Novi Sad. They had been developed from bean rhizosphere and tested in laboratory conditions prior to this study. Bean seeds were inoculated directly before sowing using 10 ml of inoculum per 100 g of seed. The following treatments were tested: 1. Rhizobium leguminosarum bv. phaseoli; 2. Azotobacter chroococcum; 3. Rhizobium leguminosarum bv. phaseoli + Azotobacter chroococcum + Streptomyces sp.; and 4. control (no inoculation). Plant material and rhizosphere soil were sampled at flowering and at full maturity. The rhizosphere soil was analyzed for total microbial abundance, the numbers of fungi, actinomycetes, aminoheterotrophs, azotobacter, and dehydrogenase activity as an indicator of the overall soil microbial activity. At full flowering, the effects of inoculation on the length of the above-ground plant part and root length were assessed. At full maturity, pod number, grain number and grain weight per plant were determined. The results of the study showed that inoculation effect depended on the type of inoculant, i.e., on interactions among the microorganisms used.