Hugo Tiago Ribeiro Amaro

Teste de envelhecimento acelerado em sementes de crambe (Crambe abyssinica Hochst), cultivar FMS Brilhante

A utilizacao de sementes de alta qualidade fisiologica merece destaque na instalacao de qualquer cultura, sendo necessario avalia-las por meio dos testes de germinacao e de vigor. O objetivo deste trabalho foi avaliar a eficiencia do teste de envelhecimento acelerado na determinacao do vigor de sementes de crambe. Foram utilizados cinco lotes de sementes de crambe, cultivar FMS Brilhante, e a qualidade inicial de cada lote foi avaliada pela determinacao do teor de agua, germinacao, primeira contagem de germinacao, emergencia de plântulas e indice de velocidade de emergencia. Para o teste de envelhecimento acelerado, as sementes foram submetidas a temperaturas de 41 e 43 oC, em câmara tipo BOD, durante 48, 72 e 96 horas. No final de cada periodo de envelhecimento, as sementes foram colocadas para germinar, conforme metodo descrito para o teste de germinacao. O delineamento experimental foi inteiramente casualizado, com quatro repeticoes por lote. O teste de envelhecimento acelerado na condicao de 41 oC, por 72 h, proporciona maior diferenciacao do vigor entre os lotes de sementes de crambe, cultivar FMS Brilhante.

Time of harvest and storability of Crotalaria juncea L. seeds

Although used as green manure, one of the challenges the cultivation of Crotalaria juncea is the low availability of quality seeds in the market. The harvest at the right time contributes to the achievement of better quality seeds. The objectives of this study were to evaluate the storability and characterize the physical and physiological changes of the seeds harvested at different times. The statistical design was completely randomized with three replications. Treatments consisted of four harvest seasons and two storage periods (0 to 8 months). The samples were collected when the plants reached 40, 60, 80 and 100% of dried pods. The following characteristics were evaluated: time for drying, moisture content, dry matter accumulation, physical purity, yield, uniformity testing, seed coat coloring, germination, germination first count test, percentage of hard seeds, speed index and percentage of seedling emergence. Data from ripening stages were submitted to regression analysis. The effect of storage within each time it was analyzed by the joint analysis of variance of the results and the Tukey test (p≤0.05). The determination of the sampling point based on the percentage of dried beans is efficiently. The physiological maturity of the seeds is achieved when the plants have about 86.1% of dry beans, with the Crotalaria juncea seeds harvesting is performed at the point where the plants have between 80 and 100% of dried pods. The storage for eight months reduces dormancy up to 75.4%.

CARACTERIZAÇÃO DA TESTA DE SEMENTES DE Apuleia leiocarpa (VOGEL) J. F. MACBR) APÓS SUPERAÇÃO DE DORMÊNCIA

The dormancy is an intrinsic seed phenomenon, functioning as natural mechanism of resistance to adverse environmental factors. Germination will occur only when it is overcome and the environmental conditions are favorable for seedling growth. The objective of this study was to analyze the effect of treatments to overcome dormancy in the structure of Apuleia leiocarpa seed testing by scanning electron microscopy. The pre-germination methods to overcome dormancy were: non-scarified seeds (control), immersion in sulfuric acid 75 and 98% for three and nine minutes and immersion in hot water at 80°C for 30 seconds. The seeds were submitted to analysis in microscopy and were evaluated by the germination test. The treatments were effective in breaking the exotesta seed of sugar cane juice, wherein the high acid induced increase in germination. The heated water caused the death of seeds.