Application of 24-epibrassinolide promotes the development and growth of Genipa americana L. seedlings under varying shading levels

Light and hormones are factors that influence plant growth and development. This study aimed to observe the effect of different concentrations of 24-epibrassinolide combined with varying levels of shading on the development of Genipa americana L. seedlings. The seedlings were placed under three shading conditions: Full sunlight, 35%, and 50%. They were then exposed to five concentrations of the hormone: 0, 10, 20, 30, and 40 nM. The experiment was arranged in a randomized block design with four blocks and five treatments, containing 20 replicates/treatment/shading condition. The results revealed that moderate shading (35%) was the optimal condition for the growth of G. americana seedlings, yielding the highest diameter (12.12 mm) and height (35.3 cm) values. Although the number of leaves was greater in the full sunlight treatment (n = 12.2), no statistically significant difference was observed compared to the 35% shading treatment. At low concentrations (10 and 20 nM), 24-epibrassinolide effectively improved growth parameters and biochemical content. The 35% shading condition provided the best overall growth, resulting in higher values for height, diameter, and leaf number, making it the most favorable environment for robust development. Thus, combining appropriate shading with hormone treatment can optimize cultivation practices, providing an effective strategy for enhancing plant growth and adaptation in varying environments.