Métodos de superação de dormência em sementes de picão-preto (Bidens pilosa)

Abstract

Black-jack (Bidens pilosa) is one of the main weed species in tropical agricultural systems due to its high competitive ability, prolific seed production, and persistence in the soil seed bank. Seed dormancy is one of the primary mechanisms that ensure its survival and also make its management more difficult. This study aimed to evaluate different methods for overcoming seed dormancy in Bidens pilosa through chemical scarification, water imbibition, and light exposure. The experiment was conducted under laboratory conditions using a completely randomized design with three treatments, four levels, and four replications, totaling 48 experimental units. The evaluated variables were germination percentage, germination speed index, mean germination time, and water uptake. The data were subjected to analysis of variance (ANOVA) using the F-test, and the means were compared by Tukey's test at the 5% probability level. The results showed a significant effect of the treatments on germination percentage and germination speed index, whereas mean germination time did not differ significantly among treatments. Chemical scarification with sulfuric acid (H₂SO₄) did not increase germination, indicating that the seeds did not exhibit pronounced physical dormancy and suggesting that the acid treatment may have reduced seed vigor. Light exposure resulted in the highest germination performance, indicating that the seeds exhibit positive photoblastic behavior. Water uptake followed the characteristic triphasic pattern of the germination process.