Nodulação de vigna unguiculata (L.) Walp. (Fabaceae) inoculada com isolados obtidos de raízes de Enterolobium contortisiliquum (Vell.) morong (Fabaceae) nativas de diferentessolos da caatinga

Abstract

The biological fixation FBN is a process of great relevance for the development of plants, and symbiotic it becomes one of the natural, biological, sustainable and safe phenomena for the plant, however it is important to emphasize that this activity has great results when the symbiosis happens with the Fabaceae family, considering that they are plants with a very high symbiotic potential when we refer to their relationship with rhizobia. Research carried out with legumes and bacteria from caatinga soils becomes a reference factor for better knowledge and understanding of this content, which is still something unknown, in that it disrespects the ecology of the caatinga. This study aimed to evaluate the nodulation potential of bacteria from caatinga soils associated with vigna unguiculata nodules. The research was developed in two stages which were named experiment 1 (authentication experiment) and experiment 2 (field efficiency experiment). The bacteria used were obtained prior to this research, and are deposited in the microorganism culture collection of the Reference Center for Recovery of Degraded Areas CRAD-AL, located at the Federal University of Alagoas (UFAL-Campus Maceió). The isolates were evaluated for their ability to form symbiosis with Vigna unguiculata, where 12 samples were used from the 28 samples of the collection. Bacteria were selected according to their phenotypic characteristics. The 12 bacterial samples were from Pão de Açúcar, Traipu, Delmiro Gouveia, and Olho D'Água do Casado. The seeds were subjected to disinfestation with alcohol (70%) for one minute, sodium hypochlorite (2%) for three minutes and five successive washings in sterile distilled water. After this process, planting was carried out, with 100g of soil added. It was stored in disinfested vases with a capacity of 300 ml, where four seeds containing autoclaved sand and vermiculite in a 2:1 ratio were added. 45 days after emergence, plants were collected, at which time the presence and absence of nodules and number of nodules per plant was determined. The experimental design was in randomized blocks with four replications. There was a significant variation in the nodulation of Vigna Unguiculata, at the level of 5% probability by Tukey's test. The soils of Pão de Açúcar and Olho D'Água do Casado provided greater nodulation compared to bacteria from Delmiro Gouveia and Traipu. In experiment two, seven bacterial samples were used. The choice of these bacteria took place after the result of experiment one, which allowed us to detect which bacteria had the best performance. Thus, after the results of experiment one, it was possible to use the bacteria: one from Pão de Açúcar, two from Traipu, one from Delmiro Gouveia, two from Olho D’Água do Casado and a commercial inoculant BR3267 and a non-inoculated control. The xperiment was conducted in a delimited area at the Federal University of Alagoas, UFAL- Campus Maceió. The design adopted was a randomized block with thirteen plots and thirteen repetitions for each inoculant. After the evaluations mentioned above, the plant biomass, root and nodules were placed to dry in an oven at 65oC for 72 hours to obtain the dry mass of the aerial part (MSPA), of the root (MSR) and dry mass of the nodules (MSN) . After collecting the data, it was possible to notice that all the bacteria nodulated, being the ones from Sugar Loaf, Delmiro Gouveia and Olho D Casa da Casa having better performance, even with the nodulation of the control.

Keywords: Biological nitrogen fixation, Caatinga, Rhizobia.