THERMAL STRESS IN THE ADEQUACY OF THE CHEMICAL SCARIFICATION PERIOD IN BRACHIARIA SEEDS

Forage seeds often have a low germination percentage due to their seeds' dormancy, such as seeds of the genus Urochloa. Chemical scarification is chosen to overcome the dormancy, yet the seed's vigor level is not taken into account. On this wise, the method can harm the seed's quality. In this context, the study aimed to investigate the appropriate scarification period in brachiaria seeds and how the lot's thermal stress can affect this result. The experimental design was completely randomized, arranged in a 3x4 factorial scheme, designated by thermal stress (0, 24, and 48 hours) and periods of chemical scarification with concentrated sulfuric acid (0, 5, 10, and 15 minutes), with four repetitions. After scarification of the treatments, the seeds were evalua ted for germination and vigor criteria. Scarification for 5 minutes is enough to express the quality of Urochloa brizantha cv. MG-5. This technique is not recommended after the seeds are severely stressed by temperature and humidity.