Sodium nitroprusside effects on the germination of pea (Pisum sativum L.) seeds

A aplicação de ON em sementes tem se mostrado promissora, uma vez que as sementes em contato com a solução de nitroprussiato de sódio (SNP), doador de ON, em geral, germinam mais e com maior velocidade, tolerando melhor tanto estresses abióticos como a deterioração natural ocasionada pelo armazenamento. Assim, na presente pesquisa, teve-se como objetivo avaliar as principais alterações que ocorrem na durante a germinação de sementes de ervilha devido à aplicação do ON. Para tanto, foram conduzidos dois experimentos. No primeiro experimento, três lotes de sementes de ervilha com diferentes níveis de qualidade fisiológica foram semeados em substrato umedecido com água (controle) ou com solução de SNP (50 μM). Adotou-se o delineamento inteiramente casualizado, com quatro repetições. Os dados foram submetidos à análise de variância e as médias foram analisadas pelo teste F a 5% de probabilidade. No segundo experimento, sementes de ervilha foram semeadas em substrato umedecido com água (controle), solução de polietilenoglicol [PEG 6000 (-0,15 MPa)] e solução de PEG 6000 + SNP (-0,15 MPa; 50 μM). O delineamento estatístico adotado foi inteiramente casualizado com quatro repetições. Os dados foram submetidos a análise de variância e as médias foram analisadas pelo teste Tukey a 5% de probabilidade. Conclui-se que o ON não aumenta a germinação das sementes de ervilha, entretanto há aumento no vigor. Sementes com menor potencial fisiológico respondem melhor à aplicação do ON. O estresse hídrico diminui a germinação e o vigor das sementes de ervilha e causa desbalanço das espécies reativas de oxigênio. A aplicação do SNP promoveu maior germinação e maior velocidade de germinação em sementes sob estresse hídrico. Houve maior atividade das amilases, das enzimas antioxidativas e menor conteúdo de H 2 O 2 , menor liberação de O 2- e menor peroxidação de lipídeos em sementes tratadas com doadores de ON.The NO application in seeds has shown promising, because the seeds in contact with the sodium nitroprusside (SNP) solution, NO donor, usually germinates more and faster and are more tolerant to abiotic stresses such as natural deterioration caused by storage. Thus, it is interesting to know how the NO acts on the seeds germination to improve the early seedling development. Therefore, the research aimed to evaluate the main changes that occur during the germination of pea seeds due the NO application. Therefore, two experiments were conducted. In the first one, three lots of pea seeds with different physiological potential levels were sown in a substrate with water (control) or with SNP solution (50 μM). It was adopted the completely randomized design with four replications. The data were subjected to variance analysis and the means were analyzed by F test at 5% of probability. In the second experiment, pea seeds were sown in a substrate with water (control), polietilenoglicol [PEG 6000 solution (-0,15 MPa)] and PEG 6000 + SNP solution (-0,15 MPa; 50 μM). It was adopted the completely randomized design with four replications. The data were subjected to variance analysis and the means were analyzed by Tukey test at 5% of probability. To conclude, the NO does not increase the germination of pea seeds, but increase the seeds vigor. Seeds with lower physiological potential gives a better response to the NO application. Water stress decrease the germination and vigor of pea seeds and cause reactive oxygen species imbalance. The SNP application promoted a higher and faster germination in seeds under water stress. There were higher activity of the amylases, higher activity of the antioxidative enzymes, less H 2 O 2 content, less O 2- liberation and consequently less lipid peroxidation in seeds treated with NO

Production of reactive oxygen species in Dalbergia nigra seeds under thermal stress

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 (O2-) and hydrogen peroxide (H2O2) 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

Performance of soybean plants as function of seed size: II. Nutritional stress

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

Biochemical and physiological analysis in carrot seeds from different orders of umbels

ABSTRACT 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 ºC (optimum) to 35 ºC (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

Lipid peroxidation and antioxidant enzymes of Jatropha curcas L. seeds stored at different maturity stages

 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.

Germination of "Solo" papaya seeds treated with plant hormones

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), GA3 (0; 10 and 50 mg / L) and KNO3 (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. KNO3 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

Germination and antioxidant action in melon seeds exposed to salt stress

Salinity influences all germination stages and may adversely affect the seedlings establishment in the field. This study aimed at assessing the effects of salt stress on the physiological potential of melon (Cucumis melo L.) seeds. Germination and activity of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POX) enzymes were assessed at the osmotic potentials of 0.0 MPa, -0.1 MPa, -0.2 MPa, -0.3 MPa, -0.4 MPa and -0.5 MPa. The enzymatic activity was assessed after 24 h, 48 h and 72 h of imbibition. Seed germination was zero at -0.5 MPa and 91 % and 85 % at -0.1 MPa and -0.2 MPa, respectively. In general, the activity of SOD, CAT and POX enzymes increased with the salt-induced stress, in the different times of imbibition, and these increases were more evident at -0.4 MPa and -0.5 MPa. The salt stress induced by NaCl diminishes the germination rate of melon seeds, particularly from the osmotic potential of -0.2 MPa. There is a significant increase in the activity of SOD, CAT and POX enzymes, mainly after 48 h of exposure.A salinidade tem influência em todas as etapas da germinação e pode afetar consideravelmente o estabelecimento de plântulas em campo. Objetivou-se avaliar os efeitos do estresse salino no potencial fisiológico de sementes de melão (Cucumis melo L.). Foram avaliadas a germinação e a atividade das enzimas superóxido dismutase (SOD), catalase (CAT) e peroxidase (POX), nos potenciais osmóticos de 0,0 MPa; -0,1 MPa; -0,2 MPa; -0,3 MPa; -0,4 Mpa; e -0,5 MPa. A atividade enzimática foi avaliada após 24 h, 48 h e 72 h de embebição. A germinação das sementes foi nula no potencial de -0,5 MPa e de 91 % e 85 %, respectivamente nos potenciais de -0,1 MPa e -0,2 MPa. De maneira geral, a atividade das enzimas SOD, CAT e POX aumentou com a indução do estresse salino, nos diferentes tempos de embebição, sendo que esses aumentos foram mais evidentes nos potenciais de -0,4 MPa e -0,5 MPa. O estresse salino induzido por NaCl reduz a germinação de sementes de melão, principalmente a partir do potencial de -0,2 MPa. Ocorre aumento significativo na atividade das enzimas SOD, CAT e POX, principalmente após 48 h de exposição

Germination of "Solo" papaya seeds treated with plant hormones

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), GA3 (0; 10 and 50 mg / L) and KNO3 (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. KNO3 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