ALLELOPATHIC INTERACTION BETWEEN Digitaria insularis AND Sesamum indicum: DIFFERENTIAL RESPONSES IN SHOOT AND ROOT GROWTH

This study aimed to evaluate the allelopathic effect of aqueous extracts of Digitaria insularis on the germination and early growth of sesame (Sesamum indicum L.) seedlings. The experiment was conducted under laboratory conditions in a completely randomized design, arranged in a 4 × 5 factorial scheme (cultivars × extract concentrations), with four replications. Four sesame cultivars (Seda, K3, Anahí, and Morena) and five extract concentrations (0, 2.5, 5, 10, and 20% w/v) were evaluated. The following variables were assessed: germination percentage, germination speed index, seedling height, root length, shoot and root fresh mass, and shoot and root dry mass. The results showed no significant effect of the extract on germination; however, significant changes were observed in seedling growth variables. An increase in seedling height and shoot biomass was observed with increasing extract concentrations, whereas root length decreased. Regression analysis indicated predominantly linear responses. These findings suggest that Digitaria insularis extract does not exert inhibitory allelopathic effects on sesame germination but induces differential physiological responses during early growth, possibly associated with hormetic effects.