EFEITO BIOESTIMULANTE DE EXTRATO DE Ascophyllum nodosum NO TRATAMENTO DE SEMENTES DE SOJA

Abstract

Soybean (Glycine max (L.) Merrill) stands out in Brazilian agriculture due to its high economic and nutritional value. This study aimed to evaluate the effects of the biostimulant Ascophyllum nodosum (Stingray®) on germination and early development of two soybean cultivars, conducted in the 2024/2025 growing season in Correntina, Bahia. The experimental design was a randomized block with four treatments (seeds treated and untreated with A. nodosum for each cultivar) and four replications of 50 seeds. The analyses included germination tests in a greenhouse, seedling emergence in beds, root length (RL), shoot length (SL), and dry matter production (DMP). Data were subjected to ANOVA and, when significant, compared using Tukey’s test at a 5% probability level. Results showed that, under controlled conditions (greenhouse), the BA007 cultivar without treatment exhibited a higher germination speed index (GSI), while A. nodosum application did not significantly increase performance for either cultivar. In seedbeds, under climatic variation (13.9 to 28.3 °C), a reduction in emergence speed was observed in treated seeds, suggesting that environmental conditions had a greater influence than the biostimulant. For DMP, a significant treatment effect was detected (p < 0.01), with BA007 treated (17.67 g) standing out, differing from the control (14.51 g) and BA522 treatments. For RL, no significant differences were observed between factors or genotype × biostimulant interaction, while for SL a significant interaction was verified, indicating genotype-dependent behavior. The coefficient of variation for RL (19.77%) was considered acceptable for field conditions. It is concluded that the response to A. nodosum extract depends on the genotype and environmental conditions. Although its application promoted an increase in DMP for BA007, the effects were not uniform across germination, early growth, and shoot development, reinforcing the need for cultivar- and environment-specific management