ABSTRACT. The objective of the present work was to investigate the antioxidant enzyme activities and the occurrence of lipid peroxidation during storage of J. curcas seeds obtained from fruits at different maturity stages. Seeds extracted from fruits collected at three stages of maturity were used, i.e., yellow, brownish-yellow, and brown (dry fruits). The seeds were subsequently stored for 18 months in Kraft paper bags in a laboratory environment. Initially as well as every three months, the seeds were evaluated for germination and electrical conductivity, and the seed embryos were evaluated for lipid peroxidation; protein content; and superoxide dismutase, peroxidase, and ascorbate peroxidase enzyme activity at the same time points. In general, the seeds from the three stages of fruit maturity did not differ regarding germination throughout the entire period of storage, although a reduction in viability was observed after nine months of storage. The electrical conductivity increased during storage and was greater for the seeds obtained from brown fruits. There was a reduction in protein content and in enzyme activities in the seed embryo, except for superoxide dismutase. No relationship was observed between reduction in seed viability and lipid peroxidation. Thus, J. curcas seeds with high initial quality can be stored under environmental conditions for up to 9, 15 and 15 months for brown (dry), yellow and brownish-yellow fruits, respectively, without a significant reduction in germination but with a reduction in seed vigour.Keywords: physic nut, seed maturation and deterioration, enzyme activity, malondialdehyde content.Peroxidação de lipídios e enzimas antioxidativas em sementes de Jatropha curcas L. armazenadas em diferentes estágios de maturação RESUMO. O objetivo do presente trabalho foi avaliar a atividade de enzimas antioxidativas e a peroxidação de lipídios durante o armazenamento de sementes de J. curcas em diferentes estádios de maturação. Foram utilizadas sementes extraídas de frutos colhidos com coloração externa da casca amarela, amarela-marrom e marrom (frutos secos). As sementes foram armazenadas por 18 meses, em embalagem de papel Kraft em ambiente de laboratório. Inicialmente e a cada três meses, as sementes foram avaliadas quanto à germinação e condutividade elétrica, e os embriões das sementes foram avaliados quanto a peroxidação de lipídios, conteúdo de proteínas e atividade das enzimas superóxido dismutase, peroxidases e peroxidase do ascorbato. Em geral, as sementes dos três estádios de maturação dos frutos não diferiram quanto à germinação durante todo o período de armazenamento, embora tenha sido observada uma redução da germinação a partir de nove meses de armazenamento. Houve redução no conteúdo de proteína e na atividade das enzimas antioxidantes no embrião das sementes dos três estádios de maturação, com exceção da superóxido dismutase. Não foi observada relação entre a redução da viabilidade das sementes e a peroxidação de lipídios. Sementes de J. curcas com elevada qualidade inici...

The high quality seed is an input with invaluable for obtaining soybean crops with higher yields; for it reflects the results of high investments in research of modern technologies, which will be converted into high productivity levels. Thus, the aim of this study was assessing performance of soybean seeds, sorted by size, and grown in soils with different phosphorus levels. To this, seeds of two soybean cultivars (MSoy 9144RR and MSoy 8527RR) were sorted with aid of circular screens with perforations of 5.5 mm and 7.5 mm in diameter. Sowing was carried out into plastic pots, with 3.0 dm³ substrate capacity each, containing a Red-Yellow Oxisol, fertilized with increasing phosphorus dosages (50, 100, 200, 300 and 400 mg. Kg-1), and performed under greenhouse environmental conditions. Seed size did not significantly influence the values obtained to the variables analyzed; however, to the larger seeds there was a trend of increase on these values. There was also a trend of increase on these values to all variables assessed when the dosages of phosphorus in the soil were increased.

-The aim of this study was to investigate the effects of some plant hormones on germination of Carica papaya L. seeds of the "Solo" group taken from fruits at maturity stages 3 and 5 (50% and 75% of the fruit skin showing a yellow color). Then, the seeds were subjected to treatments involving different combinations of acid 2-chloroethylphosphonic -(CEPA 0; 5 x 10 -7 and 5 x 10 -4 M), GA 3 (0; 10 and 50 mg / L) and KNO 3 (0 or 1 M), and germination was assessed at the 14th and 30th days. Seeds from fruits at maturity stage 3 showed increased germination when treated with all growth regulators tested. KNO 3 promoted a decrease in germination and in the germination speed index, especially in the seeds from stage 5. The plant hormones did not promote any increase in percentage of normal seedlings of papaya seeds. Two-Chloethylphosphonic acid (5 x 10 -4 M) and the gibberellic acid applied alone in the seeds from satge 3 promoted an increase in the number of normal seedlings 14 days after sowing.Index terms: Carica papaya, CEPA, AG, phytohormones, KNO 3 . Germinação de sementes de mamão tratadas com fitohormôniosRESUMO -Sementes de mamão têm germinação lenta e desuniforme o que tem sido atribuído à dormência pós-colheita. Objetivou-se com o presente trabalho avaliar os efeitos de reguladores de crescimento na germinação de sementes de mamão grupo "Solo". As sementes foram extraídas de frutos nos estádios de maturação 3 e 5, que correspondem a 50% e mais que 75% da superfície externa amarela, respectivamente. Em seguida, foram submetidas a tratamentos constituidos por diferentes combinações de ácido 2-cloroetilfosfônico -CEPA (0; 5 x 10 -7 e 5 x 10 -4 M), GA 3 (0; 10 e 50 mg / L) e KNO 3 (0 ou 1 M), avaliando-se a germinação aos 14 e 30 dias. Verificou-se aumento da germinação das sementes no estádio 3 de maturação quando tratadas com os reguladores de crescimento testados. O KNO 3 teve efeito negativo na germinação e no índice de velocidade de germinação, principalmente nas sementes do estádio 5. Não houve efeito dos reguladores de crescimento na porcentagem final de plântulas normais. O CEPA (5 x 10 -4 M) e as giberelinas empregadas isoladamente promoveram aumento do número de plântulas normais das sementes no estádio 3, aos 14 dias após a semeadura.

-Seed germination is dependent on abiotic factors, temperature being one of the main ones, whose influence causes seed damage under extreme conditions. The aim of the present study was to investigate the effect of different temperatures during germination of D. nigra seeds and their physiological and biochemical implications. We assessed germination percentage and production of superoxide anion (O 2 -) and hydrogen peroxide (H 2 O 2 ) in seeds subjected to temperatures of 5, 15, 25, 35 and 45 ºC for different periods of time. Hydration is promoted at 45 ºC and inhibited at 5ºC, without germination in either, whereas it is minimal at 15 °C and at a maximum level at 25 °C. Superoxide production increases at higher temperatures (25 and 35 ºC) after 72 hours of hydration, coinciding with the beginning of radicle protrusion. Production of hydrogen peroxide decreases at all temperatures, except for 5 ºC, with values near each other at temperatures of 15, 25, and 35 ºC, where there was radicle protrusion. Termos para indexação: floresta, fisiologia, bioquímica, jacarandá-da-bahia.

-In carrot seed production, harvesting of the umbels is generally staggered, or sometimes the whole plant is harvested with the umbels at different stages of maturation; in that case, there is a risk of harvesting immature seeds and of losses due to natural dehiscent, or to physiological deterioration as a result of unfavourable environmental factors. The present study aimed to evaluate the physiological and biochemical changes related to the maturation of 'Planalto' carrot seeds from diferent umbels. The samples were collected 120 days after anthesis, with the primary, secondary and tertiary umbels being harvested separately. Seeds were analysed for germination, first count and germination rate, at temperatures of 25 °C (optimum) to 35 °C (adverse), as well as for emergence in the greenhouse and the emergence rate. Analyses were also carried out of the enzymes peroxidase (POX), ascorbate peroxidase (APX), catalase (CAT) and superoxide dismutase (SOD), and of the total protein. Seeds obtained from the primary and secondary umbels displayed a higher rate of germination than from the tertiary umbels, with the seeds from the primary umbels showing high activity for peroxidase, catalase and superoxide dismutase, and low activity for the enzyme ascorbate peroxidase.Key words: Daucus carota L.. Physiological quality. Enzyme activity.RESUMO -Na produção de sementes de cenoura, a colheita das umbelas é geralmente parcelada ou, em algumas vezes, colhe-se a planta toda com umbelas em diferentes estádios de maturação; nesse caso, corre-se o risco de colheita tanto de sementes imaturas como de ocorrerem perdas devido à debulha natural ou por deterioração fisiológica em consequência de fatores ambientais desfavoráveis. O presente estudo teve como objetivo avaliar as alterações fisiológicas e bioquímicas relacionadas à maturação das sementes de cenoura cv. Planalto provenientes de diferentes umbelas. As colheitas foram realizadas aos 120 dias após a antese, onde foram colhidas umbelas primárias, secundárias e terciárias separadamente. Sementes foram analisadas quanto a: germinação, primeira contagem e índice de velocidade de geminação nas temperaturas de 25 ºC (ótima) e 35 ºC (adversa), além de emergência em casa de vegetação e índice de velocidade de emergência. Foram ainda realizadas análises das enzimas peroxidase (POX), ascorbato peroxidase (APX), catalase (CAT) e superóxido dismutase (SOD), além das proteínas totais. As sementes obtidas das umbelas primárias e secundárias apresentaram germinação superior às sementes das umbelas terciárias, sendo que as sementes das umbelas primárias apresentaram elevada atividade de enzimas peroxidase, catalase e superóxido dismutase e baixa atividade da enzima ascorbato peroxidase. Palavras-chave:Daucus carota L.. Qualidade fisiológica. Atividade enzimática.