Survey of scientific production on bio-inputs in Northern and Northeastern Brazil (2010-2025): A focus on plant growth-promoting microorganisms in legumes and grasses.

Using bio-inputs, particularly those based on plant growth-promoting microorganisms (PGPM), has gained momentum in Brazil as a sustainable alternative to conventional agricultural inputs. This meta-analysis synthesizes data from 1,391 peer-reviewed studies published between 2010 and 2025, focusing on the spatial, temporal, and biological dimensions of PGPM research in Northern and Northeastern Brazil. An increase in the number of publications has been observed after 2018. Geographically, 61.2% of studies originated in the Northeast—primarily in Bahia, Pernambuco, and Ceará—while 38.8% were conducted in the North, especially in Pará, Acre, and Amazonas. Leguminous species accounted for 52% of studies, reflecting their nitrogen-fixing capacity and regional agronomic importance, followed by grasses (41%) and other species (7%). Diazotrophic bacteria such as Azospirillum, Bradyrhizobium, and Herbaspirillum were the most frequently studied microbial group, consistently enhancing plant growth metrics across crop types. Seed coating was the most widely used and effective inoculation method, followed by soil drenching and foliar application. PGPM treatments significantly improved aboveground biomass, root traits (notably nodulation and root density), and crop yield, especially in legumes. Subgroup analyses identified critical moderators influencing PGPM efficacy, including inoculant type, inoculation method, soil fertility, and environmental stressors. Despite these benefits, challenges were frequently reported. Approximately 31% of studies cited inconsistent field performance, and 28% highlighted microbial viability and soil compatibility constraints. Regulatory gaps, quality control deficiencies, and biosafety concerns regarding releasing of non-native strains were also noted. These findings highlight the potential of PGPM to support regional food systems and contribute to national sustainability goals, underscoring the urgent need for improved standardization, targeted funding, and stronger policy frameworks. The study provides evidence-based insights to guide research, regulation, and investment in bio-inputs for a more equitable and resilient Brazilian agriculture.