Rizobactérias mobilizadoras de fósforo em feijoeiro comum

Abstract

The use of low quality seeds and low efficiency in the use of P by the plant are factors that negatively interfere in the productivity of beans. Studies show that the use of Plant Growth Promoting Rhizobacteria can contribute to sustainable management and can make P available to plants through the solubilization of inorganic phosphorus present in the soil. Therefore, the objective was to evaluate the effect of seed microbiolization with phosphorus-mobilizing rhizobacteria on the development of common bean seedlings, as well as to verify the use of the Neubauer technique in the selection of rhizobacteria that optimize P absorption in bean culture. . In experiment 1, a completely randomized design was used. The treatments evaluated were six rhizobacteria applied to the seeds and one control (saline). The seeds were submitted to the germination test on Germitest paper and the germination speed index, length of the root system, length of the aerial part, length and dry mass were evaluated. Experiment 2 was conducted in a greenhouse in a 7x5 factorial scheme, with rhizobacteria (Bacillus altitudinis-7, RZ-13, B. amyloliquefaciens41, Bacillus thuringiensis-66, Bacillus xiamensis-67, RZ-70 and absence of seed microbiolization ) and increasing doses of P (0; 100; 200; 400 and 800 mg dm-3). The adapted Neubauer technique was used and at 29 days of cultivation, total dry matter and leaf phosphorus content were determined. The data from the experiments were subjected to analysis of variance and when the significant F value was found, the means were compared using the Scott-Knott test at 5% probability. In the first experiment, a greater length of the root system was observed associated with treatments with B. amyloliquefaciens-41, B. xiamensis-67 and RZ 70. B. altitudinis-7, B. amyloliquefaciens-41, B. xiamensis-67 and RZ 70 promoted greater seedling length. The rhizobacterium B. amyloliquefaciens-41 promoted an increase in the germination speed index of bean seeds. In experiment 2, there was a significant response of root dry matter to the application of the treatments B. amyloliquefaciens-41 and B. xiamenensis-67. Higher P contents were identified in microbiolized plants with B. amyloliquefaciens-41, B. xiamensis-67 and RZ 70. RZ 70 promotes greater economic efficiency of phosphate fertilization in the production of total dry matter. It is concluded that rhizobacteria do not negatively affect the germination of seeds and the development of common bean seedlings. B. amyloliquefaciens-41, B. xiamensis-67 and RZ 70 stand out in both experiments. In experimental conditions, RZ-70 increases the efficiency of phosphate fertilization by common bean culture. Neubauer's technique can be a quick alternative to test the efficiency of bacteria in optimizing phosphate fertilization.