Tratamentos pré-germinativos para a superação de dormência em sementes de Panicum maximum Jacq.

Abstract

This work aimed to verify the pre-germinative treatments in Panicum maximum seeds that, isolated or associated, would result in the best germinative potential of the seeds. Developed in three chapters, the work brings in Chapter I an organized experiment in a completely randomized design, 4x3 factorial (scarification times with H2SO4: 0; 1; 3 and 5 minutes) x (temperatures: 25ºC, 30ºC and 35ºC), arranged in three repetitions with seeds of the cultivar Mombasa. The results of germination in the first count (10 Days After Sowing - DAS and successive daily counts until the 28th day), the germination speed index (IVG) and the viability of the remaining seeds were verified through the tetrazolium test. The results demonstrated that the scarification with H2SO4 for 1 minute was superior to the other treatments, and there was no significant interaction when associating the temperature with the scarification time. Chapter II, with the experiment organized in a completely randomized design, presented six concentrations of KNO3 (0.0%; 0.1%; 0.2%; 0.3%; 0.4% and 0.5%) arranged in four replications and using seeds from the cultivar Mombasa. After evaluating the results of germination (counts at 10, 14, 21 and 28 DAS), IVG and viability of remaining seeds with tetrazolium, it was possible to conclude that 0.1% KNO3 was the best treatment to stimulate seed germination of P. maximum cv. Mombasa. In Chapter III, treatments that were superior in chapters I and II were used, organized in a completely randomized, factorial 4x2 design (pre-germinative treatments: H2SO4 for 1 minute; 0.1% KNO3; H2SO4 + KNO3 and seed control without treatment) x (cultivars: Mombaça and MG12 Paredão). The germination results with counts at 10, 14, 21 and 28 DAS, IVG and the viability of the remaining seeds through tetrazolium were evaluated, and it was concluded that scarification with H2SO4 was not efficient in overcoming dormancy when compared to other treatments, except when associated with the use of KNO3 in the substrate; KNO3 was efficient in overcoming dormancy and provided excellent root development; and the cultivar MG12 Paredão showed better performance in relation to all treatments to overcome dormancy.