GERMINATION AND RE-INDUCTION OF DISSECATION TOLERANCE IN SEEDS OF Senna multijuga (RICH.) IRWIN ET BARN

O objetivo deste trabalho foi analisar diferentes m\ue9todos de supera\ue7\ue3o de dorm\ueancia, condi\ue7\uf5es \uf3timas de germina\ue7\ue3o, tais como luz, temperatura, e poss\uedvel reindu\ue7\ue3o da toler\ue2ncia \ue0 desseca\ue7\ue3o em sementes de Senna multijuga . Foram testados dois m\ue9todos de supera\ue7\ue3o de dorm\ueancia: imers\ue3o em \ue1gua com temperatura inicial de 100\ubaC (\ue1gua quente) e imers\ue3o em \ue1gua com temperatura constante a 100\ubaC por 20 segundos (\ue1gua fervente), ambos os tratamentos seguidos de repouso fora do aquecimento por 24 horas. Para o teste de germina\ue7\ue3o, foram avaliados os regimes t\ue9rmicos 25\ubaC, 30\ubaC (constantes) e 20-30\ub0C (alternados), na presen\ue7a e aus\ueancia de luz. Para o teste de reindu\ue7\ue3o da toler\ue2ncia \ue0 desseca\ue7\ue3o, foram selecionadas sementes germinadas com 1, 2, 3 e 4 mm de comprimento radicular e submetidas aos tratamentos de desseca\ue7\ue3o: sem incuba\ue7\ue3o; com incuba\ue7\ue3o em solu\ue7\ue3o de polietilenoglicol (PEG6000) nas concentra\ue7\uf5es de -1,4; -1,7 e -2,0MPa; com incuba\ue7\ue3o em solu\ue7\ue3o de PEG -1,4MPa + ABA nas concentra\ue7\uf5es de 1, 10 e 100 \u3bcM. O delineamento inteiramente casualizado (DIC) foi utilizado em todos os experimentos com 4 repeti\ue7\uf5es de 25 sementes. A supera\ue7\ue3o de dorm\ueancia utilizando \ue1gua quente proporcionou germinabilidade superior a 65%. As sementes de Senna multijuga, apesar de n\ue3o serem fotobl\ue1sticas positivas obrigat\uf3rias, apresentaram maior porcentagem de germina\ue7\ue3o sob condi\ue7\uf5es de luz. Foi poss\uedvel observar a retomada do crescimento ap\uf3s a secagem em sementes germinadas com rad\uedculas de at\ue9 3 mm de comprimento.The aims of this study were to verify the effects of different tests in the overcoming dormancy, excellent germination terms, as light and temperature, and the possibility of re-induction of desiccation tolerance in Senna multijuga seeds. We evaluated two tests for overcoming dormancy: immersion in water with an initial temperature of 100\ubaC (hot water) and immersion in water at a constant temperature at 100\ubaC for 20 seconds (boiling water), both treatments followed by rest out of the heating for 24 hours. For the germination test, we evaluated 25\ubaC, 30\ubaC (constant) and 20-30\ubaC (alternate), in the presence and absence of light. For the reinduction of desiccation tolerance, we selected seeds germinated with 1, 2, 3 and 4mm of radicle length. We submitted the germinated seeds to the follow treatments: no incubation, incubation in polyethylene glycol (PEG6000) at the -1,4, -1,7 and -2,0MPa; incubation in PEG -1,4MPa + ABA at the concentrations of 1, 10 and 100\u3bcM. The tests followed a completely randomized design (DIC) using 4 repetitions of 25 seeds. The overcoming dormancy using hot water provided the best germination (65%). The Senna multijuga seeds are not photoblastic required, but in light conditions the germination was higher. We observed the resumption of the radicle growth in germinated seeds of up to 3mm length