Germinação de sementes de urucum em função de métodos de superação de dormência e temperaturas

Abstract

Bixa orellana L. is a perennial plant known as annatto or achiote, which belongs to the Bixaceae family and is widely used in cooking, due to its properties of natural dye, whose germination is affected by its own characteristics. This study aimed at elucidating the dormancy mechanism of annatto seeds and evaluating the effect of different methods for breaking it, under different germination temperatures. The scarification methods were: chemical (with concentrated sulfuric acid and ethanol, under immersion for five minutes), physical (scarification with sand paper) and thermic (in water at 70°C, for two minutes, and then under temperatures of 20°C, 25°C, 30°C and 20-30°C, for germination). The amount of water absorbed by seeds, and percentage, first counting and germination rate, as well as hypocotyl and taproot length, were evaluated. For the seeds that did not germinate, the tetrazolium test was applied to verify their viability. It was concluded that the treatments used for dormancy breaking did not affect the annatto seeds viability. Scarification with sand paper or sulfuric acid, for five minutes, and temperatures of 25°C or 20-30°C are recommended.