Physical and physiological changes of Crambe abyssinicaHochst seed during maturation

Determination of seed-maturation indicators enables the identification of the idealmoment for harvest to achieve the best production and conservation potential. Our objective here was to evaluate some physical and physiological changes of crambe (Crambe abyssinica Hochst) seeds as possible indicators of seed maturation. Crambe floweringwas monitored in Dourados, Mato Grosso do Sul, Brazil. Plants were tagged, and 13, 22, 26, and 28 days after the initiation of flowering, the seeds were collected and following physical attributes evaluated: length, diameter, total mass, dry matter and water content. Physiological quality of the seeds was assessed using the germination test, by registering the percentage of normal seedlings and dormant seeds, immediately after each harvest, and again after six months of storage. The water-absorption curveswere characterized as a function the seed-development stages. All physical attributes were observed to increase because of the accumulation of reserve substances during seed development, except for water content, which gradually decreased from 72.2% at the start of development to 29.5% at maturity. At 28 days after anthesis the germination percentage of crambe seeds at physiological maturity was only 17%, indicating that they became dormant while maturing. However, seed germination rate was 89% after six months of storage, indicating that dormancy was almost fully overcome after this period.

Foliar application of plant growth regulators changes the physiological quality of crambe seeds

The application of plant growth regulators can manipulate the development of cultivated plants, and their physiological effects may be reflected in the physiological quality of the seeds. This study evaluated the effects of plant growth regulators (PGR) on the physiological quality of crambe seeds produced in the 2014 and 2015 harvests. During crop development, we applied two foliar sprayings of the following treatments: 1) control treatment with distilled water; 2) indole-3-acetic acid 100 mg L-1 (IAA); 3) 3-gibberellic acid P.A. 100 mg L-1 (GA3); 4) commercial PGR Stimulate® 6 mL L-1. The seeds were harvested and evaluated for water content, germination percentage and germination speed index (GSI), electrical conductivity and concentrations of leached Ca, Mg and K ions. Means were compared by Tukey ́s and Dunnett tests (p<0.05). Applying Stimulate® increased the germination percentage and the germination speed index, while IAA application showed an opposite effect, increasing the electrical conductivity of crambe seeds. Calcium leaching decreased with IAA application, and all regulators reduced K leaching. We therefore infer that the application of plant growth regulators influences the physiological quality of crambe seeds.

pH of exudate test in the physiological quality of crambe seeds / Teste do pH do exsudato para avaliação da qualidade fisiológica de sementes de crambe

Crambe is a rapeseed with high oil content and can be used as a winter cover or as a source of raw material for the production of biodiesel, however espite the growing interest in the culture, research on the subject is still incipient, especially concerning the seed production and analysis technology. The purpose of this study is to evaluate the physiological quality of crambe seeds, 'FMS Brilhante' cultivar, by testing the pH of exudate. Five seed lots were submitted to the determination of water content and the tests of germination and vigor (first count, emergence and tetrazolium). In the conduction of pH exudate test, temperatures (25 and 30oC), and periods of seed imbibition in water (15, 30 and 45 minutes) were tested. The experiment was conducted in a completely randomized manner, with four replicates, and the mean values were compared by the Tukey test at 5% probability; Pearson correlation between the pH of the exudate and initial tests was also made. Testing the pH of exudate is promising for separating lots of crambe seeds and the following combinations of 25°C/30 minutes or 30°C/45 minutes can be used.(AU)

O crambe é uma brássica com alto teor de óleo, podendo ser utilizada como cobertura de inverno ou fonte de matéria prima para a produção de biodiesel, porém, apesar do crescente interesse pela cultura, as pesquisas ainda são incipientes, principalmente quanto à tecnologia de produção e análise de sementes. O objetivo neste trabalho foi avaliar a qualidade fisiológica de sementes de crambe, cultivar 'FMS Brilhante', pelo teste do pH do exsudato. Para tanto, cinco lotes de sementes foram submetidos à determinação do teor de água e a testes de germinação e vigor (primeira contagem, emergência e tetrazólio). Na condução do teste do pH do exsudato, foram testadas as temperaturas constantes de 25 e 30ºC e períodos de embebição das sementes em água de 15, 30 e 45 minutos. O experimento foi realizado no delineamento inteiramente casualizado com quatro repetições e as médias foram comparadas pelo teste de Tukey a 5% de probabilidade; também foi feita a correlação de Pearson entre o pH do exsudato e as avaliações iniciais. O teste do pH do exsudato é promissor na separação de lotes de semente de crambe, podendo ser utilizadas as combinações 25ºC/30 minutos ou 30oC/45 minutos.(AU)