PSV-26 Phenotypic plasticity of Gliricidia sepium under different planting densities.

Abstract Gliricidia sepium (Jacq.) Kunth ex Walp (G. sepium) is a versatile leguminous tree with significant potential for enhancing ecosystem services and supporting sustainable agriculture. Its ability to adapt to varying planting densities is crucial for maximizing biomass yield and forage quality. This study investigated the anatomical, productive, and bromatological responses of G. sepium to different planting densities, testing the hypothesis that increased density induces anatomical adaptations that enhance biomass production. A randomized block experiment evaluated three planting densities (10,000, 20,000, and 30,000 plants ha⁻¹), analyzing micromorphometric traits, biomass yield, bromatological composition, and key correlations among these variables. Leaf micromorphometric analysis revealed density-dependent changes in the abaxial epidermal surface, upper and lower collenchyma, lacunar parenchyma, and stomatal number and density. In stems, significant variations were observed in the medullary radius, cortex, and periderm, while roots exhibited structural modifications in the periderm and phloem. Higher planting densities positively influenced vegetative growth, with total edible plant length increasing linearly (P = 0.002), with no change in total forage production (P > 0.10). Among bromatological traits, hemicellulose content showed a decreasing trend as planting density increased (P = 0.09). Strong correlations between micromorphometric, biometric, productive, and bromatological variables suggested an integrated structural and functional adaptation to planting density. A density of 30,000 plants ha⁻¹ was optimal, balancing anatomical development, productivity, and quality. These findings confirm the phenotypic plasticity of G. sepium, demonstrating its ability to structurally and functionally adapt under intensive planting conditions. Such adaptations enhance its potential for high-yield forage production, supporting its domestication and sustainable use for ruminant feeding systems.