| Congresso Brasileiro de Microbiologia 2023 | Resumo: 1149-2 | ||||
Resumo:Cowpea, a crop characterized by high demand but low productivity in the semi-arid region of northeastern Brazil, is primarily affected by abiotic factors, such as water scarcity and high temperatures, which restrict crop growth and productivity. Therefore, the objective of this study was to assess the impact of inoculation and co-inoculation in cowpea plants subjected to water restriction or not. The experiment consisted of two stages: the first stage was conducted in the greenhouse at DTCS/UNEB, organized in randomized blocks with four replicates. Three isolates previously identified with the potential to promote cowpea growth (T1-ESA380 and T2-ESA386), two recommended bacteria (T3-SEMIA6462 and T4-SEMIA6464), three co-inoculations (T5-ESA380+SEMIA6464 and T6-ESA386+SEMIA6464), and two control groups (T7-With mineral nitrogen addition, T8-Without mineral nitrogen addition) were tested. The treatments were subjected to two water regimes: full irrigation (100% of evapotranspiration throughout the crop cycle) and intermittent water regime (10 days without irrigation followed by 5 days of rehydration before harvest). Analyses were conducted at 35 days after emergence (DAE) and included the evaluation of nodule number, shoot and root dry mass, root system volume, and gas exchange parameters. Data were subjected to Tukey's test at a significance level of 5%. The second experiment, using the inoculants SEMIA 6464 (=3262), ESA386, and a combination of 3262 with ESA386, as well as controls with mineral nitrogen and negative control, was conducted in the field under the same irrigation conditions as the greenhouse, with water deficit imposed 15 days before harvest, organized in four randomized blocks. Plants were harvested at two cowpea phenological stages: at the R2 stage (beginning of flowering - 45 DAE) and at pod maturity (65 DAE). Nodule number, shoot dry mass, and yield were evaluated. Data were analyzed using Tukey's test at a significance level of 10%. The results indicated that the co-inoculation treatment with ESA386 was superior to other treatments, showing a significant increase in CO2 assimilation rate (102.9%) and stomatal conductance (119.0%) compared to the control receiving mineral nitrogen addition. Under intermittent irrigation conditions, ESA 386 isolates, both with and without co-inoculation, and ESA380 helped plants maintain higher CO2 assimilation compared to other treatments. Furthermore, the co-inoculation treatment with ESA386 showed higher transpiration rates after plant rehydration. Shoot dry mass also increased when cowpea was inoculated with ESA386, either alone or in consortium with a3262. The co-inoculation treatment demonstrated higher yield under intermittent irrigation conditions, and when the crop's full water demand was provided, ESA386 achieved values similar to the control with mineral nitrogen. In summary, these results suggest that co-inoculation had a positive effect, and inoculation with the ESA386 treatment, in consortium with BR3262, improved cowpea gas exchange performance and had a positive impact on yield when subjected to intermittent irrigation. Palavras-chave: water stress, biological nitrogen fixation, dry forest, semiarid, rhizobia Agência de fomento:CAPES - Fundação Coordenação de Aperfeiçoamento de Pessoal de Nível Superior | |||||