Effect of gibberellic acid and Ascophyllum nodosum seaweed on the growth and development of Ornithogalum saundersiae Baker

Abstract

Ornithogalum saundersiae Baker is a bulbous ornamental species native to southern Africa, with relatively recent cultivation in Brazil. It is highly valued in floral arrangements and bouquets. Ornithogalum has low establishment costs and is easy to manage. One of the main challenges for its cultivation is the scarcity of products that can be used in cultivation, such as plant growth regulators and biostimulants. Gibberellic acid (GA₃) is a plant growth regulator known to promote earlier flowering in various ornamental species, while Ascophyllum nodosum seaweed extract has potential for promoting vegetative growth. This study aimed to evaluate the influence of gibberellic acid (Progibb 400®) and seaweed extract (Acadian®) on the growth and development of Ornithogalum saundersiae. A completely randomized design was used in a 4 × 3 factorial scheme, with four concentrations of GA₃ (0, 250, 500, and 750 mg L⁻¹) and three concentrations of A. nodosum extract (0, 2, and 4 ml L⁻¹), with one plant per plot and six replicates. Before planting, O. saundersiae bulbs were immersed in solutions containing the products and distilled water, the twelve combinations for 15 minutes, allowed to dry for one hour, and then planted. There was no significant difference between concentrations in the vegetative growth of O. saundersiae. All tested concentrations promoted earlier flowering compared to the control, with the best results observed at 500 mg L⁻¹ of GA₃ combined with 2 ml L⁻¹ of A. nodosum extract, which accelerated flowering by 27 days.