Potential of Hydrolate and Aqueous Extract of Gallesia integrifolia (Spreng.) Harms on the Germination of Sorghum Seeds

Abstract

Sorghum bicolor (L.) Moench is an important crop for animal feed, owing to its tolerance to marginal soils and challenging climatic conditions. However, agricultural technologies such as pesticides and genetically modified (GM) crops raise environmental concerns, underscoring the need for natural seed treatments. This study evaluated the effects of hydrolate (a by-product of essential oil hydro distillation) and the aqueous extract from Gallesia integrifolia Spreng. Harms (pau-d'alho) on germination and initial growth of Sorghum bicolor (L.) Moench seeds. Experiments used a 2×5 factorial (product × concentration: 0, 5, 10, 15, 20 mL/100 kg seeds) in a completely randomized design with four replicates. Parameters assessed: First Count (FC), Total Germination (TG), germination speed index (GSI), root length (RL), shoot length (SL), total dry mass (TDM). Data were analyzed by ANOVA, Tukey test (5%), and regression. Hydrolate-treated seeds showed 25% higher RL (6.51 cm vs. 5.27 cm) and 17% higher SL (4.89 cm vs. 4.15 cm) than extract-treated seeds (p≤0.05). No differences in FC (21.5% vs. 22.0%), TG (26% vs. 28%), GSI (5.66 vs. 5.44), or TDM (5.08 vs. 5.33 mg). RL increased linearly with hydrolate dose; the extract peaked at 8.5 mL/100 kg and then declined, indicating phytotoxicity >10 mL/100 kg. G. integrifolia hydrolate enhances sorghum seedling vigor without toxicity up to 20 mL/100 kg, outperforming aqueous extract. This valorizes an aromatic by-product for sustainable seed treatment, supporting green chemistry in agriculture. Future studies should fractionate the hydrolate using GC-MS to isolate bioactive compounds and evaluate their efficacy under field conditions in the edaphoclimatic environment of Paraná.