Rapid tests have been essential to evaluate the physiological potential of seeds and the tetrazolium test is one of those which have been used by seed companies. The objective of the study was to establish the procedure for the tetrazolium test in Libidibia ferrea (Mart. Ex Tul.) L.P. Queiroz var. ferrea seeds. For this, three tetrazolium solution concentrations (0.05, 0.075 and 0.1%) and three staining periods (1, 3 and 6 hours) at temperatures of 35 to 40 °C were tested. The seeds were also evaluated by the germination test, whose result was compared with viability by the tetrazolium test. The experimental design was completely randomized in a factorial design 3 x 3 + 1 (three concentrations x three periods + a control = germination test) for each temperature. Viable seeds in the tetrazolium test were compared by Tukey’s test (p ≤ 0.05), while the comparison between the viable seeds with germination test was carried out by Dunnett’s test (p ≤ 0.05). It is recommended that the tetrazolium test for L. ferrea is carried out at a concentration of 0.05% for three-hour staining under 35 °C or 40 °C.

A B S T R A C TSunflower is a species with multiple potentialities and its yield can be affected by the presence of soluble salts in the soil, which is common in arid, semi-arid and irrigated regions. The objective of this study was to evaluate the effect of hydropriming as inducer of salinity tolerance in seeds and seedlings of sunflower, hybrid MG305CP. The germination tests were set with four replicates of 50 seeds per treatment, maintained in germinator at 30 ºC for ten days. To simulate salinity, sodium chloride diluted in distilled water was used at electrical conductivities of 0 (control), 4, 8, 12 and 16 dS m -1. On the tenth day, the number of normal seedlings was counted and the length and dry matter of shoots and roots were determined. Seedling fresh matter was used to determine the contents of total chlorophyll, total soluble sugars and proline. The experimental design was completely randomized, in a 2 x 5 factorial scheme (with and without hydropriming and five levels of salinity). Hydroprimed sunflower seeds showed greater vigor expression, with higher number of normal seedlings and faster germination.Hidrocondicionamento como indutor de tolerância à salinidade em sementes de girassol R E S U M O O girassol é uma espécie com múltiplas potencialidades, cuja produtividade pode ser afetada pela presença de sais solúveis no solo, fato comum em regiões áridas, semiáridas e irrigadas. Nesta pesquisa, objetivou-se avaliar o efeito do hidrocondicionamento como indutor de tolerância à salinidade em sementes e plântulas de girassol, híbrido MG305CP. Os testes de germinação foram instalados com quatro repetições de 50 sementes por tratamento, sendo mantidos em germinador a 30 ºC por dez dias. Para simular a salinidade, utilizou-se cloreto de sódio diluído em água destilada nas condutividades elétricas de 0 (controle); 4; 8; 12 e 16 dS m -1. No décimo dia, computou-se o número de plântulas normais, comprimento e massa seca de parte aérea e raiz. A partir da matéria fresca de plântulas foi determinado o teor de clorofila total, açúcar solúveis totais e prolina. O delineamento experimental foi o inteiramente casualizado, em esquema fatorial 2 x 5 (com e sem hidrocondicionamento e cinco níveis de salinidade). As sementes de girassol hidrocondicionadas apresentaram maior expressão de vigor com maior número de plântulas normais e germinação mais rápida.

This study evaluated the physical and physiological attributes of saved cowpea seeds (Vigna unguiculata L. Walp.) used in the Brazilian semi-arid area and compared them with certified seed varieties. The study tested 37 saved seed samples from the state of Rio Grande do Norte and two varieties of certified seeds (“BRS Guariba” and “BRS Pujante”) from the production field of Embrapa Products and Market, Petrolina, PE, Brazil. The seeds were tested for moisture, hectoliter weight, weight of 1,000 seeds, and physical purity to evaluate the physical quality. Germination, first germination count, field emergence, emergence rate index, shoot dry mass, and accelerated aging were tested for physiological quality. The saved cowpea seeds showed great differences, suggesting the influence of genetic variability and different growing environments. The use of saved cowpea seeds by small farmers in the semi-arid areas of Northeastern Brazil is impractical, because these seeds have inferior physical and physiological qualities compared to certified cowpea seeds.

Germination test for papaya seeds demands thirty days to obtain the results, which is a long period for decision-making. Thus, rapid tests become essential tools to evaluate seed viability, and the tetrazolium test is an alternative for this purpose. Hence, this study aimed to establish the adequate procedure to apply this test, in order to reduce the time of evaluation of papaya seeds. For that, four tetrazolium solution concentrations (0.05, 0.1, 0.5 and 1%) and three staining times (3, 6 and 9 hours) were tested at temperatures of 35 and 40 ºC. The experimental design was completely randomized in 4 × 3 + 1 factorial scheme (concentrations × staining times + one control = germination test). It was found that the tetrazolium test allows to evaluate the physiological quality of papaya seeds, thus reducing the time for decision-making. For the test, we recommend using the concentrations of 0.1% for 9 hours or 1% for 6 hours of staining, at temperature of 40 ºC.

RESUMO -Os testes de germinação e de vigor são componentes essenciais do processo de controle de qualidade das empresas produtoras de sementes. Diante disso, nesta pesquisa o objetivo foi estudar a metodologia do teste de condutividade elétrica, verificando sua eficiência na identificação de diferentes níveis de vigor de lotes de sementes de coentro. Para tanto, utilizaram-se quatro cultivares (Português, Super Verdão, Tabocas e Verdão), cada uma representada por quatro lotes de sementes, que inicialmente foram submetidas às avaliações do grau de umidade, germinação, primeira contagem de germinação e emergência de plântulas. O teste de condutividade elétrica foi realizado com 25 e 50 sementes embebidas em 50 e 75 mL de água destilada, a 25 ºC, por 2, 8 e 24 horas. O teste de condutividade elétrica é eficiente para a avaliação do potencial fisiológico de sementes de coentro quando conduzido com 50 sementes imersas em 50 mL de água destilada, a 25 ºC, após duas horas de embebição. Palavras-chave:Coriandrum sativum. Hortaliça. Temperatura. Embebição. Vigor. ABSTRACT -The tests of germination and vigour are essential components of the quality control process of seed producers. Therefore, the aim of this research was to study the methodology of the test of electrical conductivity, verifying its efficiency in identifying different levels of vigour in batches of coriander seed. To do this, four cultivars were used (Português, Super Verdão, Tabocas and Verdão), each represented by four batches of seed, which were initially subjected to evaluations of moisture content, germination, germination first count and seedling emergence. The test of electrical conductivity was carried out on 25 to 50 seeds soaked in 50 and 75 mL of distilled water at 25 °C for 2, 8 and 24 hours. The test of electrical conductivity is efficient to evaluate the physiological potential of coriander seeds when carried out with 50 seeds immersed in 50 mL of distilled water at 25 °C, after soaking for two hours.

The beggartick (Bidens subalternans L.) is one of the main weeds present in agricultural crops, capable of adapting to different environmental conditions. The water stress caused by water deficiency can affect the germination of weed seeds and, consequently, their capacity to colonize the agroecosystem. Knowledge of germination under water stress can be important to obtain an adequate management of the species in the agricultural systems. The objective of this study was to determine the effects of water stress on the germination process and vigor of two batches of Bidens subalternans seeds under different osmotic agents. It was completely randomized experimental design was used, with four replicates of 25 seeds. The treatments were arranged in factorial 6 × 2, with the first factor corresponding six levels of osmotic potentials (0.0, -0.2, -0.4, -0.6, -0.8 and -1.0 MPa) and the second the batches (Pernambuco and Ceará). For the simulation of the water stress, the test of germination was installed in substrate paper blotting, moistened with solutions of polyethylene glycol (PEG 6000) and mannitol. The analyzed variables were germination, germination speed index, length and seedling dry mass. Water stress reduced germination, seed vigor and growth of seedlings in all batches of B. subalternans. Seeds of B. subalternans presented greater tolerance to stress induced by mannitol than to PEG-6000 in terms of germination and germination speed index. Regardless of the osmotic agent used for stress induction, B. subalternans seeds did not tolerate water stress higher than -0.4 MPa.

The physiological quality of seeds used in agricultural production is one of the main factors that should be considered when implanting the culture. This study aimed at evaluating the quality of bur gherkin seeds, cv. Liso de Calcutá, coming from plants grown from seeds that were previously treated with biostimulant (0, 5, 10, 15 and 20 mL. kg-1 seeds) and cultivated in two irrigation water salinities (0.5 and 3.5 dS. m-1). Initially, the water content of seeds was determined and the following tests were performed: germination, accelerated aging, greenhouse emergence, emergence speed index, height and dry mass of seedling aerial part. It was found that the physiological quality of bur gherkin seeds coming from plants that were subjected to salt stress is negatively affected, and that the use of biostimulant, applied via seeds, provides beneficial effects on the physiological quality of seeds produced in the next generation.

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