Teste de tetrazólio para Pinus taeda: preparo, coloração e classes de viabilidade das sementes

The objective of this work was to evaluate preparation and staining methods used in the tetrazolium test for Pinus taeda seeds, with the definition of viability classes. The procedures carried out were those described in the rules for seed testing in Brazil and Association of Official Seed Analysts, as well as an alternative method for the tetrazolium test. For each procedure, different combinations of types of seed cuts, concentrations of tetrazolium salt, and exposure periods were used. The test conducted with the alternative procedure (longitudinal cut adjacent to the embryo and staining of only the half with the embryo) is the most practical. The obtained results allowed classifying seeds into two different viability classes (viable and nonviable), and 0.2% tetrazolium salt for 4 hours is the most effective combination.O objetivo deste trabalho foi avaliar métodos de preparo e coloração usados no teste de tetrazólio para sementes de Pinus taeda, com definição de classes de viabilidade. Foram realizados os procedimentos descritos nas regras para análise de sementes no Brasil e na Association of Official Seed Analysts, além de um método alternativo para o teste de tetrazólio. Para cada procedimento, foram utilizadas diferentes combinações de cortes da semente, concentrações do sal de tetrazólio e tempo de exposição. O teste conduzido com o procedimento alternativo (corte longitudinal adjacente ao embrião e coloração somente da metade que contém o embrião) apresenta a maior praticidade. Os resultados obtidos permitiram classificar as sementes em duas classes de viabilidade (viável e não viável), e 0,2% de sal de tetrazólio por 4 horas é a combinação mais eficiente

DETERMINATION OF MOISTURE CONTENT AND STORAGE POTENTIAL OF GUANANDI SEEDS

Guanandi is a native forest species with particularities that make it difficult to store of seeds, because of its recalcitrant behavior and since a specific and practical protocol to determine the moisture content of its seeds is not available yet. This work had the purpose to test procedures to determine the moisture content and to study different environmental conditions of the storage of the guanandi seeds. In order to determine the moisture content, the low-temperature oven method at 101 – 105°C was used, testing seed preparation methods (intact, cut in half and fragments smaller than 7.0 mm) and different drying periods. Four environments (wet chamber, dry chamber, cooler and laboratory environment) were tested for the storage of the seeds, with two packaging types, during four periods (0, 1, 2, 3 and 4 months). For the statistical analysis, a completely randomized design, with a factorial arrangement, was used for moisture content; a split-split plot design was used for storage. A regression analysis was performed to evaluate the physiological potential and moisture content during the storage, adjusting the significant equation by Tukey's test. From the obtained results, it was observed that the low-temperature oven method 101 - 105°C / 17 h, using intact seeds, should be used to determine the moisture content of guanandi seeds. The best combination of environment and packaging to store seeds was the laboratory environment condition (average between 19.6 - 23.1 °C and RH 53-62%) in polyethylene packaging

QUALIDADE SANITÁRIA E FISIOLÓGICA DE SEMENTES DE ARAUCÁRIA DURANTE ARMAZENAMENTO

Araucaria angustifolia is a species of ecological and social-economic importance in the southern Brazil region, but it is at risk of extinction. Its seeds are classified as recalcitrant, requiring storage under controlled temperature and humidity to obtain greater longevity. Another aspect is the seed health quality, which is impaired by high seed moisture content that causes fungus proliferation and may reduce germination and seedling quality. The objective of this study was to evaluate the physiological and sanitary quality of araucaria seeds treated with 0.5, 1 and 3 % of sodium hypochlorite (NaClO) and stored at different periods (2, 4, 6, 8 and 12 months). The seed quality was evaluated by germination, vigor and seed health tests. The disinfection of seeds, regardless of the concentration used, temporarily delayed the seed germinations, but did not negatively affect seedling emergence. After 12 months of storage, the seeds showed infection by Schizophyllum commune, which caused the reduction of the germination. The seeds treated with NaClO showed lower fungal incidence, especially Schizophyllum commune, ensuring the seed health quality during storage for 12 months. The treatment with NaClO positively favors the physiological quality of Araucaria seeds that will be stored for a period exceeding four months.Araucaria angustifolia é uma espécie de importância ecológica e socioeconômica na região Sul do Brasil, porém, em risco de extinção. Sua semente é classificada como recalcitrante, necessitando armazenamento sob temperatura e umidade relativa controladas para maior longevidade. Outro aspecto refere-se à qualidade sanitária das sementes, a qual é prejudicada pelo elevado teor de água que causa a proliferação de fungos, os quais podem reduzir a germinação. Este trabalho teve como objetivo avaliar a qualidade sanitária e fisiológica de sementes de araucária desinfestadas com solução de hipoclorito de sódio (NaClO) a 0,5; 1 e 3 % e submetidas a diferentes períodos de armazenamento (2, 4, 6, 8 e 12 meses). A qualidade das sementes foi avaliada pelos testes de germinação, vigor e sanidade. A desinfestação das sementes, independentemente da concentração utilizada, retardou temporariamente a germinação das mesmas, porém, não afetou negativamente a emergência das plântulas. Após 12 meses de armazenamento, verificou-se a infecção das sementes por Schizophyllum commune, o que causou a redução da germinação. As sementes tratadas com NaClO apresentaram menor incidência de fungos, especialmente Schizophyllum commune, garantindo a qualidade sanitária das mesmas durante o armazenamento por 12 meses. O tratamento com NaClO favorece positivamente a qualidade fisiológica das sementes de araucária que serão armazenadas por período superior a 4 meses

POLYPHENOLS IN YERBA MATE SEEDS: POTENTIAL INHIBITORS OF GERMINATION

Due to its economic, social, and ecological potentials, yerba mate can be a source of employment and income in the southern region of Brazil. The objectives of the present study was to (1) quantify the total polyphenols in fresh yerba mate seeds (FS), seeds dehydrated for 70 d (SD), and seeds stratified in sand for 180 d (SS); (2) evaluate the potential germination and growth inhibitory effects of water, ethanol + water (1:1), and ethanol (99%) extracts of yerba seeds (FS, SD, and SS) using lettuce seedlings; and (3) verify the presence of polyphenols in fresh seeds of yerba mate through histochemical methods. In the bioassay, extracts of yerba mate seeds were used in the germination of lettuce seeds. For the histochemical analysis, sections of yerba mate seeds were stained with specific dyes. The results revealed that yerba mate fresh seeds contain higher concentration of phenolic compounds, which decreased in dehydrated seeds, and almost no phenolic compound was observed in stratified seeds. The bioassay results showed that the polyphenols present in the extracts of yerba mate seeds resulted in phytotoxic effect on the roots of lettuce seedlings. The histochemical observations revealed the presence of “lignified rough barrier” and phenolic compounds between the endocarp and endosperm of the yerba mate seeds.Due to its economic, social, and ecological potentials, yerba mate can be a source of employment and income in the southern region of Brazil. The objectives of the present study was to (1) quantify the total polyphenols in fresh yerba mate seeds (FS), seeds dehydrated for 70 d (SD), and seeds stratified in sand for 180 d (SS); (2) evaluate the potential germination and growth inhibitory effects of water, ethanol + water (1:1), and ethanol (99%) extracts of yerba seeds (FS, SD, and SS) using lettuce seedlings; and (3) verify the presence of polyphenols in fresh seeds of yerba mate through histochemical methods. In the bioassay, extracts of yerba mate seeds were used in the germination of lettuce seeds. For the histochemical analysis, sections of yerba mate seeds were stained with specific dyes. The results revealed that yerba mate fresh seeds contain higher concentration of phenolic compounds, which decreased in dehydrated seeds, and almost no phenolic compound was observed in stratified seeds. The bioassay results showed that the polyphenols present in the extracts of yerba mate seeds resulted in phytotoxic effect on the roots of lettuce seedlings. The histochemical observations revealed the presence of “lignified rough barrier” and phenolic compounds between the endocarp and endosperm of the yerba mate seed

QUANTIFICAÇÃO DO TEOR DE ÁGUA DE SEMENTES DE Araucaria angustifólia (Bertol.) Kuntze

Sementes de Araucaria angustifolia são consideradas de comportamento recalcitrante, não tolerando a desidratação. Assim, a determinação do teor de água é importante para o monitoramento da perda de água durante o armazenamento e, consequentemente, para a manutenção da sua viabilidade. O objetivo do presente trabalho foi estabelecer critérios para avaliação do teor de água de sementes de araucária. Para tanto foram testadas duas quantidades de sementes por amostra, quatro formas de preparo da semente (sementes íntegras, cortadas em três partes, cortadas em quatro partes e cortadas em fragmentos menores que 7,0 mm); e dois métodos de secagem (estufa a 105°C e estufa a 101-105°C), por diferentes períodos. Com base nos resultados obtidos pode-se concluir que o procedimento mais indicado para a determinação do teor de água de araucária é a utilização do preparo das sementes cortando-as em três partes, pelo método de estufa a 101-105 °C, durante 17 h

Características morfofisiológicas dos frutos e das sementes de guanandi durante a maturação e o ponto de coleta

The objective of this work was to determine the relationship of the morphological and physiological characteristics of guanandi (Calophyllum brasiliense) fruit and seeds with ripening and harvesting time. The reproductive cycle of a native plant population, located in the coast of the state of Paraná, Brazil, was monitored from anthesis until fruit dispersion, during three years. Monthly harvests were performed, and the morphological and physical aspects (color, size, dry mass, and moisture content) of fruit and embryos were evaluated, as well as the physiological ones (germination and vigor) of seeds. The ripening process of guanandi seeds occurred between 200 and 240 days after anthesis (DAA), with anthesis peak in February and fruit dispersion in October. The maximum dry matter mass accumulation was not synchronized with the maximum physiological potential of the seeds. Germination potential was reached close to the middle of the maturation process, and maximum vigor at the end of the cycle. Fruit external color did not change from 110 DAA onwards. The morphological characteristics related to harvesting time are fruit pulp and embryo weakly adherent to the endocarp and to the tegument, respectively, as well as the dark-brown color of these tissues.O objetivo deste trabalho foi determinar a relação das características morfológicas e fisiológicas do fruto e da semente de guanandi (Calophyllum brasiliense) com a maturação e o ponto de coleta das sementes. O ciclo reprodutivo de uma população de plantas nativas, localizada no litoral do Estado do Paraná, foi monitorado da antese até a dispersão dos frutos, durante três anos. Realizaram-se coletas mensais, tendo-se avaliado aspectos morfológicos e físicos (cor, tamanho, massa de matéria seca e teor de água) dos frutos e dos embriões, bem como os fisiológicos (germinação e vigor) das sementes. O processo de maturação das sementes de guanandi ocorreu entre 200 e 240 dias após antese (DAA), com pico da antese em fevereiro e dispersão dos frutos em outubro. O máximo acúmulo de massa de matéria seca não esteve sincronizado com o máximo potencial fisiológico das sementes. O potencial germinativo foi atingido próximo à metade do processo de maturação, e o máximo vigor no final do ciclo. Não houve mudanças na coloração externa dos frutos a partir de 110 DAA. As características morfológicas relacionadas ao ponto de coleta são a fraca adesão da polpa do fruto e do embrião ao endocarpo e ao tegumento, respectivamente, além da coloração marrom-escura desses tecidos