In vitro culture of forage peanut embryos under different gibberellin concentrations

Resumo

Seed dormancy is a constraint in the propagation of forage peanut, limiting large-scale production. Tissue culture techniques, particularly embryo rescue, offer a promising alternative for breaking dormancy and ensuring uniform seedling establishment. This study was developed in order to evaluate the effect of gibberellic acid (GA₃) on embryo germination, with the objective of establishing an efficient protocol for in vitro embryo cultivation. Embryos extracted from four seed lots were cultured on Murashige and Skoog (MS) medium supplemented with five concentrations of GA₃ (0, 10, 20, 40, and 80 mg L^-1). Seeds were surface-sterilized with 70% ethanol followed by 2% sodium hypochlorite and rinsed with deionized water. Embryos were excised using a sterile scalpel in a laminar flow hood and cultured as explants for regeneration. After 21 days, germination rate, seedling growth parameters, and photosynthetic pigment contents were assessed. Statistical analyses included analysis of variance (ANOVA) and polynomial regression, with treatment effects compared using Tukey’s test (p ≤ 0.05). A quadratic response was confirmed for most parameters, underscoring the importance of dose optimization. Moderate GA₃ concentrations (40 mg L^-1) significantly improved embryo germination compared to the control, whereas higher concentrations (80 mg L^-1) negatively impacted chlorophyll content and optimal shoot and root development. GA₃ application during in vitro culture influenced seedling development, promoting shoot elongation and altering pigment composition. In vitro culture proved to be an effective approach for assessing the physiological response of Arachis pintoi seedlings to varying gibberellin levels, contributing to a better understanding of dormancy-breaking mechanisms in this species.