Biouninema no desempenho fisiológico de sementes e no controle de Meloidogyne javanica em feijoeiro

Abstract

The association of beneficial microorganisms with common bean seeds can favor the establishment of the crop, providing vigorous seedling growth, in addition to reducing the Meloidogyne javanica population, which is responsible for large losses in crop production. At the State University of Montes Claros, a formulation based on Bacillus subtilis-34 (Biouninema) in rice was developed, which proved to be efficient in promoting growth and controlling Meloidogyne spp. in vegetable crops. The objective was to evaluate the effect of microbiolization of BRS Estilo bean seeds with different concentrations of Biouninema on the physiological performance and control of M. javanica in bean plants. The first experiment consisted of evaluating the physiological performance of seeds microbiolized with Biouninema. The experiment was set up in a completely randomized design with seven treatments (Biouninema diluted at 25%, 50%, 75% and 100% and controls: distilled water, water with increments and Onix®) and four replications. To treat the seeds, they were disinfected using 70% alcohol/30s, 0.5% sodium hypochlorite/60s and then immersed 3 times in sterilized distilled water for 30 seconds and dried for 6 hours in a laminar flow chamber under UV light. Next, the seeds were immersed in the different treatments for 30 minutes and dried for 120 minutes. The formulation in the dilutions and the seeds treated with the treatments were subjected to analysis of the number of colony forming units (CFU) per seed through serial dilution 10-1 to 10-4 and plating of dilutions 10-2 , 10-3 and 10-4 on tryptic soy agar. Germination, root protrusion, first germination count, germination speed index (IVG), root length and aerial part of seedlings were evaluated. Serial dilution demonstrated that as the bacterial concentration in the sprays increased, the number of CFU in the spray and in the seed increased. The UFC values per seeds were 6.46x106 at a concentration of 25% and 1.22x107 at a concentration of 100%. Seeds treated with 25% Biouninema provided a higher percentage of germination in the first count and greater root length. Greater shoot length was provided by Biouninema at 25 and 50%. Higher values of root protrusion and germination speed index (GVI) were provided by the treatment of bean seeds with 25% Biouninema. A lower percentage of abnormal seedlings was found in Biouninema treatments at concentrations of 25%, 50% and 75%. Higher germination percentages were provided by the 25% formulation (83.50%). Biouninema at a concentration of 25% favors the physiological performance of BRS Estilo bean seeds. The second experiment was carried out in a greenhouse in a randomized block design (DBC) with four treatments, 27 mL of 25% Biouninema, 54 mL of 25% Biouninema, Onix® and pure seed) and four replications. The treatments were applied to BRS-Estilo bean seeds and after planting in pots containing previously autoclaved sandy soil at 29 and 42 days after seedling emergence. The application of a suspension containing 5000 eggs plus occasional second-stage juveniles (J2) of M. javanica to the soil was done 15 days after plant emergence. The data were subjected to analysis of variance and the means were compared using the Scott Knott test at 5% significance. After 50 days of nematode inoculation, fresh weight of the root, pod, number of pods, number of leaves, stem diameter, plant height, fresh and dry matter weight of the aerial part and SPAD index were evaluated. In addition, the variables number of galls, egg masses and eggs per root, number of J2 and reproduction factor were evaluated. The doses of 54mL and 27mL of the bacterial formulation and Onix® promoted lower averages for the number of galls, masses and number of eggs when compared to the control. For the reproduction factor, a reduction was observed when doses of 54 mL and Onix® were used in relation to the control. There was no effect of treatments on the number of J2 nematodes and on vegetative characteristics.