Josué Bispo da Silva

Superação de dormência em sementes de beterraba por meio de imersão em água corrente

The presence of germination inhibitors in the fruit of beetroot can reduce the stand of crop. The present work aimed to evaluate the interference of immersion period in running water in the physiological performance of the beetroot seeds. Seeds from cultivar Top Tall Early Wonder were submitted to the action of running water during 0 (control), 1; 1,5; 2; 3; 4; 5 and 6 hours, dried and physiologically evaluated using germination test. Washing the seeds during two hours was enough to increase the germination.

Avaliação do potencial fisiológica de sementes de beterraba

As informacoes disponiveis na literatura nacional sobre a avaliacao do vigor de sementes de beterraba sao escassas, embora essa cultura seja de grande importância. O objetivo do trabalho foi definir metodologia para avaliar o potencial fisiologico das sementes, comparando resultados obtidos em laboratorio com a emergencia de plântulas em campo. Sementes de beterraba, cultivar Top Tall Early Wonder, representadas por cinco lotes adquiridos no comercio, foram avaliadas quanto a viabilidade (teste de germinacao) e ao vigor (testes de primeira contagem, velocidade de germinacao, envelhecimento acelerado tradicional e com solucao saturada de NaCl e emergencia de plântulas em campo). O teste de envelhecimento acelerado com solucao salina saturada manteve baixo o teor de agua e nao reduziu a intensidade de deterioracao das sementes. Os testes de envelhecimento acelerado tradicional e com solucao de NaCl, ambos a 42oC, mostraram-se adequados para identificar diferencas no potencial fisiologico de sementes de beterraba.

Deterioração controlada em sementes de beterraba

The vigor test is a fundamental test used to evaluate the physiological potential of produced and commercialized seeds. Controlled deterioration was studied as a method to evaluate the physiological potential of beetroot seeds (Beta vulgaris). After immersing the fruits in running water, eight seed lots of cultivar Top Tall Early Wonder were evaluated as to germination and seedling emergence. The seed water content (SWC) was adjusted using the wet atmosphere and moist substrate methods. The controlled deterioration test was a completely randomized design with eight replicates of 25 seeds and was conducted at 45 oC using a SWC of 22% or 24% and deterioration times of 12, 24 and 36 hours. The experimental design for seedling emergence tests was also completely randomized but used four replicates of 50 seeds. The data were statistically analyzed for each combination of SWC and deterioration period separately and the means compared by the Tukey test (p<0.05). Simple correlation analysis was run using the data from seed laboratory tests and seedling emergence. The results indicate that SWC adjustment should be carried out only using the moist substrate method. Physiological potential of beetroot seeds can be evaluated using the controlled deterioration test with parameters of 45 oC, 24 hours and 22% SWC.

Método alternativo para submeter sementes de amendoim à solução de tetrazólio

To determine the viability of peanut seeds by means of the tetrazolium (TZ) test, the methodology in use nowadays is that by which the seeds, after imbibition in water, have their tegument removed and are then immersed in bulk in the TZ solution. This technique hinders the contact between the tissues of the internal surfaces of the seed cotyledons and the TZ solution because the previous period of water imbibition is not long enough to separate the cotyledons. Thus, the access of the TZ solution to the inner surfaces of the cotyledons and to the embryonic axis between them is very difficult or even impossible. Based on the assumption that this procedure tends to yield results which do not correlate well with seedling emergence in the field, a new technique was attempted by which the seeds, after imbibition, in addition to having their tegument removed, were manually separated in their cotyledons, with the embryonic axis remaining attached to one of them, and the two cotyledons of the same seed were then immersed in the TZ solution in an individual cell of a PVC tray. The assumption was found to be correct : the alternative technique, probably because it resulted in more clearly defined images of the tissues located inside the cotyledons internal surfaces, allowed, in comparison with the results of the conventional technique, more precise predictions of the seeds germination performance in the field.

Desempenho de sementes de soja submetidas a diferentes potenciais osmóticos em polietilenoglicol

With the aim at determining the physiological potential and germinative performance of soybean seeds, two lots were evaluated by germination, cold, accelerated aging, electrical conductivity tests and osmotic stress, at potentials 0.0 (control), -0.1, -0.2, -0.3, -0.4, -0.5, -0.6 and -0.7MPa. The experimental design used was completely randomized, with four replicates of 50 seeds, except to electrical conductivity, with two replicates of 50 seeds. Additionally, the germination under osmotic stress was submitted to regression analysis. The osmotic stress in polietileneglycol, in potential equal or smaller than -0.6MPa, is a promising procedure to evaluate the physiological potential of soybean seeds; decreasing values of osmotic stress reduce germination, while osmotic stress level nearby zero may cause seeds invigoration.

Deterioração controlada para avaliar o potencial fisiológico de sementes de beterraba

Seeds of vegetable crop species always present high commercial value, so the physiological potential must be efficiently evaluated. The controlled deterioration is a recommended test to evaluate seed vigor of small-seeded vegetable crops, such as beetroot seeds. This research was run in order to determine the best controlled deterioration test procedures for beetroot seeds and its relationship with field seedling emergence. Seven commercial seed lots of the cultivar Top Tall Early Wonder were used. After washing in running water, the seeds were tested for germination, speed of germination, accelerated aging, seedling field emergence, emergence rate and controlled deterioration (41 and 45°C, moisture contents of 22, 24 and 26% and exposure times of 12, 24 and 36 hours). The combination of 41°C/24%/12 hours, 41°C/24%/36 hours, 41°C/26%/36 hours and 45°C/24%/24 hours showed potential to evaluate vigor of beetroot seeds. However, the combinations of 41°C/24%/12 hours or 45°C/24%/24 hours decreased the conduction time of the test.

Efeito da irrigação sobre o potencial fisiológico de sementes de soja em semeadura de inverno

Periodo seco e temperaturas amenas sao condicoes climaticas ideais durante a maturacao e colheita de sementes de soja. O objetivo foi verificar o efeito da irrigacao no periodo pos-maturidade fisiologica, sobre o potencial fisiologico de sementes de soja semeadas no inverno. A disposicao dos tratamentos seguiu esquema fatorial envolvendo tres cultivares (IAC-19, Conquista e IAC 8-2) e duas epocas de interrupcao da irrigacao (inicio do estadio R7 e irrigacao ate 14 dias apos R8). Foram feitas amostragens (colheitas) no inicio do estadio R7, 3, 7, 10, 14 (estadio R8) e 28 dias apos o inicio do estadio R7. Para as avaliacoes utilizaram-se os testes de germinacao, de envelhecimento acelerado e de condutividade eletrica e determinou-se a porcentagem de sementes manchadas e defeituosas. Nas condicoes em que foi realizado o experimento, concluiu-se que a irrigacao apos o estadio R7 nao compromete e pode ate melhorar o potencial fisiologico das sementes produzidas; a producao de sementes de soja em semeadura de inverno e possivel em funcao de condicoes climaticas favoraveis.