Growth of pecan seedlings in response to inoculation with beneficial microorganisms

Global pecan production is estimated at 320,000 tons, with the United States and Mexico responsible for approximately 90% of this output. Brazil ranks fourth worldwide, producing 7,200 tons, mainly in the states of Rio Grande do Sul (6,600 tons, 91,6%) and Paraná (300 tons, 5%). Since production is concentrated in southern Brazil, harvesting takes place during the off-season in the USA and Mexico, enabling Brazilian pecans to reach higher market values. This study aimed to evaluate the growth of potted pecan seedlings (cv. Barton) inoculated with Trichoderma harzianum and Azospirillum brasilense. Seedlings were inoculated in the soil on the day of planting, using manufacturer-recommended doses. Results demonstrated that microbial inoculation produced distinct beneficial effects on seedling development. A. brasilense increased plant dry mass, peroxidase activity, and phosphorus uptake, while Trichoderma harzianum enhanced leaf chlorophyll content, peroxidase activity, and phosphorus content. By contrast, co-inoculation produced no significant effects across the measured variables. Overall, inoculation with beneficial microorganisms improved seedling performance by promoting greater growth, reducing oxidative stress enzyme activity, and ensuring adequate absorption of all essential macronutrients.