Resumo: A inclusão do uso de ferramentas computacionais no controle da qualidade de sementes tem-se destacado com o intuito de auxiliar em maior assertividade na caracterização de lotes de maior potencial. Assim, o objetivo deste estudo foi investigar por meio de uma abordagem computacional a análise de parâmetros morfológicos que caracterizem a emergência da raiz primária na avaliação do vigor de sementes de tomate. Para isso, cinco lotes de sementes foram analisados quanto a sua germinação e vigor (emergência de plântulas e análise de imagens de plântulas). Em paralelo, a emergência da raiz primária foi analisada utilizando visão computacional assistida; as imagens registradas durante o progresso de germinação foram processadas com o software ImageJ® para obtenção dos parâmetros de relação de aspecto e área da semente. As diferenças de vigor entre lotes de sementes de tomate podem ser identificadas com base na emergência da raiz primária e o processamento computacional das imagens baseado na relação de aspecto apresenta-se como um procedimento eficiente para a caracterização da emergência da raiz primária na avaliação do vigor de sementes de tomate.

Abstract: The use of computational tools has become notable in seed quality control to assist in confirming seed lots of higher potential. Thus, the aim of this study was to use a computational approach to investigate analysis of morphological parameters that characterize primary root emergence in evaluation of tomato seed vigor. For that purpose, five seed lots were analyzed for germination and vigor (seedling emergence and analysis of seedling images). A parallel analysis of primary root emergence was made using computer-assisted imaging; the images recorded as germination proceeded were processed with the ImageJ® software to obtain aspect ratio and seed area parameters. Vigor differences among tomato seed lots can be identified based on primary root emergence, and computer image processing based on aspect ratio proves to be an efficient procedure to characterize emergence of the primary root in evaluation of tomato seed vigor.

ABSTRACT Spinach seeds are sensitive to high temperatures during germination and plant growth. It is known that seed priming with water or with seaweed extract (SWE) may enhance germination and seedling growth. The objective of this study was to evaluate the effects of seed priming with SWE (Ascophyllum nodosum) on the germination, seedling growth and antioxidant capacity of spinach seedlings under conditions of heat stress. Five concentrations of SWE (0.0, 0.15, 0.30, 0.60 and 1.2%) were used for priming the seeds under two temperatures (15 and 30 °C). Seeds primed with 0.3% SWE had the greatest activity of antioxidant metabolism and showed improved germination percentage, germination speed and seedling vigor under conditions of heat stress (30 °C) compared to nonprimed controls. Hydropriming and priming with 0.3% SWE resulted in lower contents of hydrogen peroxide (H2O2) and malondialdehyde (MDA) under heat stress than control (nonprimed spinach seeds). This study showed that seed priming with SWE was effective to mitigate stress due to high temperatures and to improve spinach seed germination and seedling vigor.