Biological nitrogen fixation (BNF) can provide the necessary nitrogen for bean crops; however, for this to occur, important limitations involving the inoculant application technology need to be overcome.The use of co-inoculation is a management technique used to obtain benefits and increase the potential of N₂ fixation from the association between bacteria from the rhizobia group, such as R. tropici, and bacteria that promote plant growth, such as A. brasilense, in association with the addition of nutrients that allow greater efficiency of bacteria fixing atmospheric N₂. This study aimed to evaluate the bean response to the reinoculation of R. tropici in co-inoculation with A. brasilense in a mixture with the micronutrients Co/Mo, in the winter season of 2021, in Anápolis-GO, Brazil. A randomized block design was used, with four replications, and the following treatments (TRs) were studied: TR1—reinoculation with R. tropici; TR2—reinoculation with co-inoculation of R. tropici + A. brasilense; TR3—reinoculation of R. tropici + Mo/Co micronutrients; TR4—reinoculation with co-inoculation R. tropici + A. brasilense + Mo/Co micronutrients; TR5—inoculation via seed, without reinoculation; TR6—mineral N fertilization in the sowing furrow and topdressing; TR7—control, without any N source. At stage R6, nodulation characteristics (number and dry mass of nodules) and the morphophysiological parameters of the plants (main root length, root dry mass, plant height, shoot dry mass, leaf area, and leaf N content in the shoot) were evaluated. At harvest, the final plant stand and components (number of pods per plant, number of grains per pod, and average weight of one hundred grains) were determined, in addition to grain yield. It was concluded that inoculation followed by reinoculation in topdressing with R. tropici in co-inoculation with A. brasilense plus Mo/Co, compared to mineral nitrogen fertilization, improves the efficiency of the nodulation process and the morphophysiological characteristics of the common bean crop. Seed inoculation and topdressing application with R. tropici, associated with co-inoculation with A. brasilense + Mo and Co, have the potential to completely replace mineral nitrogen fertilization in common bean crops.

This study evaluates the impact of Rhizobium tropici reinoculation and Azospirillum brasilense co-inoculation at different growth stages on the physiological quality of common bean seeds. A randomized block design was used, assessing germination, vigor, electrical conductivity, seedling length, and dry mass. Treatments T7 (co-inoculation R. tropici + A. brasilense at R5) showed the highest germination rates, indicating enhanced seed viability. The accelerated aging test revealed that T7 exhibited greater resistance to stress, presenting greater seedling vigor, whereas T10 and T11 were more susceptible. The electrical conductivity results remained stable across treatments, suggesting that cell membrane integrity was not significantly compromised. Seedling length and dry mass did not present significant variations, reinforcing the idea that early germination and vigor are primary indicators of seed quality. Canonical discriminant analysis and MANOVA confirmed significant treatment differences, highlighting the influence of inoculation strategies on seed physiology. Overall, co-inoculation with Rhizobium tropici and Azospirillum brasilense (particularly in T7) demonstrated potential to improve seed quality at lower cost, offering sustainable alternatives for optimizing agricultural production.

The common bean relies on biological nitrogen fixation to meet part of its nitrogen requirements. This study aimed to evaluate the effect of reinoculation with Rhizobium tropici, alone or combined with Azospirillum brasilense, at different phenological stages. The experiments were conducted in the winter of 2023 and the rainy season of 2023/24, and significant differences were observed between seasons, mainly due to temperature and water stress, which impacted nodulation, plant growth and grain yield. However, appropriate water management mitigated these limitations, allowing reinoculation combined with co-inoculation at the V4 stage to improve nodular and morphophysiological traits, ensuring adequate nutrition through biological nitrogen fixation. This strategy promoted nodulation and plant development, resulting in an 8.5% increase in yield compared to nitrogen fertilization (80 kg ha⁻¹), reaching 2197.87 kg ha⁻¹. These results suggest that reinoculation with co-inoculation at the V4 stage can enhance biological nitrogen fixation, reduce dependence on synthetic fertilizers and serve as a sustainable and economically viable alternative.

Spray drift of agricultural pesticides compromises application efficiency and increases environmental risk. This study evaluated the drift-reducing potential of three oil-based adjuvants through droplet spectrum characterisation and computational simulation. Experiments were conducted at the Agricultural Mechanisation Laboratory of the Federal University of Viçosa using a laser diffraction particle analyser (Malvern Spraytec) and an XR11003 nozzle positioned 0.3 m from the laser lenses, operated at 300 kPa. Droplet diameters corresponding to the 10th, 50th, and 90th percentiles of spray volume (Dv0.1, Dv0.5, and Dv0.9), droplet size uniformity (Span), and the volumetric percentage of droplets ?100 µm (%V?100 µm) were measured. These diameters, together with discharge height (0.5 m), wind velocity (2 m s?¹), temperature (25 °C), and relative humidity (75%), were used as inputs in the DRIFTSIM model. Water produced the lowest Dv0.5 (172.96 µm), the highest %V?100 µm (23.73%), and the greatest drift distance (9.88 m). The addition of adjuvants increased Dv0.5 and reduced %V?100 µm. Áureo provided the greatest reduction in drift distance (83.9%) and drift potential (71.5%), followed by Assist (71.96% and 58.9%) and Agefix (33.0% and 26.1%). Oil-based adjuvants significantly reduced drift, indicating their potential as effective tools to enhance spray efficiency, increase environmental safety, and minimise non-target contamination.

Research aimed at investigating the ideal plant arrangement system of common beans under intercropping with castor hybrids is necessary, as intercropping is a common practice in Brazil, and this practice affects the morphophysiological behavior of both crops. The objective of this study was to evaluate the consociation systems of common bean plants with small-sized castor hybrid, in three agricultural years, in the edaphoclimatic conditions of the Cerrado of Goiás, Brazil. In the three experiments, the randomized block design with four repetitions was used, involving the combination of five simultaneous sowing systems: beans sown on the castor row, on the inter-row, on the row + inter-row and beans and castor in monocropping. The bean cultivar used was Pérola; for castor the Agima hybrid was used. The plant height, primary yield components and the yield of the beans were evaluated, while for castor was evaluated the plant height, stem diameter, number of racemes per plant, plus the yield, in addition to the area equivalence index (AEI) to verify the efficiency of the intercropping. The arrangement of bean plants cv. Pérola on row and row + inter-row of the Agima 110204 castor hybrid provides higher yields of the legume. The yield of castor hybrids is not influenced by the common bean crop. The growing of common bean and the castor hybrid in the intercropping system is more efficient than the monocropping of both crops.