ABSTRACT Water stress during wheat seed germination and seedling establishment for affect the percentage and speed of germination. Silicon (Si) is related to plant tolerance to different types of stress, then the application of this nutrient in the mother plant during seed production could contribute to the improvement of the seed quality and, consequently, its tolerance to stress. The aim was to evaluate the effect of foliar application of silicon on the tolerance of wheat seeds, produced under different irrigation levels, to water stress during germination and initial seedling growth. Wheat seeds were produced under three irrigation depths (0, 50 and 100% of the total required irrigation) applied after the anthesis. The silicon was supplied in two doses by foliar application (0 and 5 mM of Si). The germination and seedling growth were performed under water stress induced by PEG 6000 at the -0.2; -0.4; -0.6 MPa osmotic potentials. In addition, in the control only distilled water was used. The reduction of the osmotic potential reduced seed germination, germination speed and seedling growth. Irrigation depths, as well as foliar application of Si, during seed production did not influence the physiological quality and tolerance of seeds to water stress during germination.

Resumo: O armazenamento pós-colheita de frutos carnosos é uma estratégia usada para melhorar a qualidade das sementes. O objetivo deste estudo foi avaliar o armazenamento pós-colheita de frutos de C. baccatum var. baccatum (pimenta cumari) e relacioná-lo à atividade de enzimas antioxidantes e ao potencial fisiológico das sementes. Frutos de cor vermelha (65 dias após a antese) foram colhidos e armazenados a 20 °C por 0, 5, 10, 15 e 20 dias. As sementes foram removidas e avaliadas quanto ao grau de umidade, qualidade fisiológica, atividade de enzimas antioxidantes e conteúdo de proteínas. As médias foram ajustadas às equações de regressão e depois avaliadas por análise multivariada (PCA). A umidade e o peso de 100 sementes diminuíram com o armazenamento pós-colheita. Os períodos de armazenamento de 5 e 10 dias levaram a um aumento na germinação. A condutividade elétrica foi maior nos períodos de armazenamento de 0 e 20 dias. A matéria seca e o teor de proteína aumentaram aos 5 e 10 dias. As enzimas exibiram reduções de atividade comparando 0 e 20 dias. O armazenamento pós-colheita de frutos de C. baccatum por 5 e 10 dias melhora o potencial fisiológico das sementes e está relacionado à maturidade fisiológica. A maturação incompleta de sementes de cumari obtidas a partir de frutos não armazenados (0 dias), está relacionada a maior atividade enzimática, maior estresse oxidativo e baixa germinação e vigor. O não armazenamento pós-colheita dos frutos e o armazenamento por mais de 10 dias contribui para o menor potencial fisiológico de sementes de pimenta cumari.

Abstract: Post-harvest storage of fleshy fruit is a strategy used for improving seed quality. The aim of this study was to evaluate post-harvest storage of the fruit of C. baccatum var. baccatum (cumari pepper) and relate it to antioxidant enzyme activity and seed physiological potential. Red-colored fruit (65 days after anthesis) was gathered and stored at 20 °C for 0, 5, 10, 15, and 20 days. The seeds were removed and evaluated for moisture content, physiological quality, antioxidant enzyme activity, and protein content. The means were fitted to regression equations and then passed through multivariate analysis (PCA). Seed moisture and 100-seed weight decreased through post-harvest storage. The 5- and 10-days storage periods led to an increase in the germination. Electrical conductivity was greater for the 0- and 20-day storage periods. Dry matter and protein increased in the 5- and 10-days. Enzymes exhibited reductions of activity comparing 0 and 20 days. The post-harvest storage of C. baccatum fruit for 5 and 10 days improves seed physiological potential and is related to physiological maturity. The incomplete maturation of cumari seeds obtained from unstored fruit (0 days) is related to greater enzyme activity, greater oxidative stress, and low germination and vigor. The lack of post-harvest storage of fruit and storage of fruit for longer than 10 days contributes to a lower physiological potential of cumari pepper seeds.