Germination and initial growth of Helianthus annuus L. (ASTERACEAE) submitted to presoaking in different concentrations of Gibberellic Acid (GA3)

Abstract

This paper aimed to assess the seed germination and early growth of sunflower (Helianthus annuus L.) seedlings subjected to pre-soaking in gibberellin. A completely randomized design was used with four replications of 25 seeds which were soaked in water for 24 hours (control) and for the same period in solutions of gibberellic acid (GA3) at concentrations of 5, 10 and 20 mg.L 1. Seeds were placed on two sheets of filter paper previously moistened with 10 mL of distilled water in petri dishes and subjected to an average temperature of 28 ± 2 ° C under white light from fluorescent lamps at 32.85 ?mol.m2.s-1 at the seed level until germination. The variables Germinability (G%), Index of Germination Speed (IVG), total length of seedlings (CP), shoot length (CA), longest root length (RL), Fresh Matter (FM) and Dry Matter (DM). The results indicated that pre-soaking the sunflower seeds at concentrations of 5 mg l-1 GA3 resulted in better values for all variables, except for the longest root length and germination speed index for which the concentration of 10 mg.L-1 GA3 gave better results. Compared to the highest concentrations of GA3 currently used in sunflower cultivation, it is possible to reduce production costs by using lower concentrations of plant growth regulator as found in this work for the species.