Resumo: A definição de metodologias que permitam avaliar o potencial fisiológico das sementes de grão-de-bico é importante para assegurar a comercialização de lotes com alto desempenho em campo. Assim, objetivou-se determinar as condições mais adequadas para a condução do teste de condutividade elétrica em sementes de grão-de-bico visando a classificação de lotes quanto ao vigor. Para tanto, sementes de cinco lotes da cultivar BRS Aleppo e de quatro lotes da cultivar Cícero foram submetidas a diferentes testes para a caracterização da sua qualidade inicial e os resultados comparados com os obtidos no teste de condutividade. Para avaliar a condutividade elétrica, 5 períodos de embebição (2, 4, 8, 12 e 24 horas) foram combinados a 4 volumes de água (75, 100, 150 e 250 mL) sob a temperatura de 25 °C. O teste de condutividade elétrica é eficiente para a avaliação do potencial fisiológico de sementes de grão-de-bico fornecendo informações equivalentes a outros testes de vigor. Para a condução do teste de condutividade elétrica recomenda-se a utilização de 50 sementes imersas em 150 mL de água, por 24 horas, a 25 °C.

Abstract: The definition of methodologies that allow evaluating the physiological potential of chickpea seeds is important to ensure the commercialization of lots with high performance. Thus, this research aimed to determine the most suitable conditions for conducting the electrical conductivity test in chickpea seeds to classify lots according to vigor level. Therefore, seeds from five lots of cultivar BRS Aleppo and four lots of cultivar Cícero were subjected to tests to characterize their initial quality and the results were compared with those obtained in the electrical conductivity test. To assess electrical conductivity, five soaking periods (2, 4, 8, 12, and 24 hours) were combined with four volumes of water (75, 100, 150, and 250 mL) at 25 °C temperature. The results show that the electrical conductivity test is efficient in evaluating the physiological potential of chickpea seeds, providing information equivalent to other vigor tests. For the electrical conductivity test, it is recommended to use 50 seeds soaked in 150 mL of water, for 24 h, at 25 °C.

ABSTRACT This study aimed to anatomically characterize the extrafloral nectaries (EFNs) of annatto (Bixa orellana) and determine the composition of its nectar in order to better understand their structure and function during organ development. Standard light and scanning electron microscopy techniques were used for anatomical analysis, and test-strips and a refractometer for determining nectar composition. Both receptacle and stem EFNs were found to possess similar anatomy and nectar composition, and to secrete from early to advanced developmental stages of the organs to which they are associated. EFNs consisting of uniseriate epidermis, nectariferous parenchyma and subnectariferous parenchyma were found located where vascular tissue is immersed. Some layers of nectariferous parenchyma exhibited sclerification and cells with phenolic compounds or calcium oxalate druses were present. Nectar exuded by stomata was acidic, diluted and found to contain sugar. The anatomical and histochemical features of annatto EFNs ensure their integrity and nectar secretion function during the development of buds, flowers and fruits.

RESUMO A colheita das sementes de cenoura no momento adequado tem reflexos diretos sobre a sua qualidade fisiológica. O objetivo do trabalho foi avaliar as alterações fisiológicas, anatômicas e histoquímicas em sementes de cenoura colhidas em diferentes estádios de desenvolvimento e estabelecer a época mais adequada para a colheita. Foram colhidas umbelas secundárias aos 14, 21, 28, 35, 42, 49, 56 e 63 dias após antese (DAA). Para a caracterização anatômica e histoquímica os cortes foram corados com Azul de toluidina, Xylidine Ponceau, Lugol, Sudan black B e submetidos à luz polarizada. As sementes foram submetidas aos seguintes testes: grau de umidade, matéria seca, germinação, primeira contagem, porcentagem e índice de velocidade de emergência de plântulas. Sementes de cenoura ‘Brasília’, aos 14 DAA, encontram-se em divisão e expansão celular e apesar da reduzida matéria seca, lipídios foram identificados no endosperma. Aos 21 DAA, além de lipídios, proteínas e amido foram identificados. A maturidade fisiológica das sementes ocorreu aos 35 DAA, com o endosperma ocupando praticamente todo volume das sementes, o embrião ocupando uma pequena região cilíndrica e o tegumento apresentando uma única camada de células. Nesta fase, as sementes apresentaram 56% de grau de umidade e a coloração do pericarpo era verde-amarelo. A máxima germinação e vigor das sementes ocorreu aos 30 DAA, um pouco antes da maturidade fisiológica (35 DAA). Portanto, a época ideal para a colheita das sementes de cenoura ‘Brasília’ é a partir de 30 DAA, quando as sementes apresentam máxima qualidade fisiológica.

ABSTRACT The adequate time for carrot seed harvest influences its physiological quality. The objective of this study was to evaluate physiological, anatomical and histochemical changes in carrot seeds harvested at different stages of development and to establish the most appropriate harvest time. Secondary umbels were harvested at 14, 21, 28, 35, 42, 49, 56 and 63 days after anthesis (DAA). For seed anatomical and histochemical characterization, sections were stained with Toluidine blue stain, Xylidine Ponceau, Lugol’s iodine, Sudan Black B and submitted to polarized light. Seed moisture content, seed dry matter, germination, first count, emergence percentage and emergence speed index of seedlings were evaluated. Cultivar Brasília carrot seeds at 14 DAA are in cell division and expansion. In addition, as lipids were identified in the endosperm, despite the seed low dry matter. At 21 DAA, reserve substances such as protein and starch were also identified. Along the seed development process, deposition of lignin occurs in the endocarp cells, and this collapsed lignified layer represents the resistance layer of the seeds. Physiological maturity, represented by the maximum dry matter accumulation, occurs at 35 DAA, with the endosperm occupying almost all volume of seeds, the embryo occupying a small cylindrical region and the integument showing a single layer of cells. At this time, the seeds presented 56% moisture content and the color of the pericarp is green-yellow. Maximum seed germination and vigor occurred at 30 DAA, just before physiological maturity was reached (35 DAA). Thus, the ideal time to harvest the seeds of cultivar Brasília is from 30 DAA, where the seeds have maximum physiological quality.