RESUMO -A alface é a hortaliça folhosa de maior importância na alimentação dos brasileiros. Seu plantio é feito por meio de sementes, cujo tamanho reduzido dificulta o seu manuseio. Além disto, essas sementes apresentam dificuldades na germinação quando submetidas a condições desfavoráveis de umidade e temperatura. O presente trabalho teve como objetivo estudar o desempenho fisiológico de sementes nuas e peletizadas de alface da cv. Karla sob diferentes potenciais hídricos e temperaturas. As sementes foram colocadas para germinar sobre papel filtro umedecido com solução de polietileno glicol (PEG 6000), nos níveis de zero, -0,3; -0,6; e -0,9MPa, associados às temperaturas de 20, 25, 30 e 35ºC. A qualidade fisiológica das sementes foi avaliada por meio do teste de germinação, primeira contagem e índice de velocidade de germinação. Concluiu-se que para potenciais hídricos menores ou iguais a -0,3MPa e nas temperaturas iguais ou superiores a 25ºC ocorreu redução na velocidade e porcentagem de germinação de sementes de alface da cv. Karla. O potencial hídrico de -0,9MPa e/ou a temperatura de 35ºC impediram a germinação das sementes nuas e peletizadas. As sementes nuas tiveram maior redução na qualidade fisiológica do que as sementes peletizadas, quando submetidas a condições de estresses hídrico e térmico.Termos para indexação: germinação, potencial hídrico, temperatura, qualidade fisiológica. PERFORMANCE OF BARE AND PELLETED LETTUCE (Lactuca sativa L.) SEEDS EXPOSED TO HYDRIC AND THERMAL STRESSESABSTRACT -Lettuce is the most important leafy vegetable in Brazil. Its planting is made by seeds, which are small, making their handling difficult. Moreover lettuce seeds present low germination when submitted to unfavorable moisture and temperature conditions. The objective of this work was to study the physiological performance of bare and pelleted lettuce seeds, cv. Karla, under different hydric and temperature potentials. Both kinds of seeds were placed to germinate on filter paper wetted with solutions of polyethylene glycol (PEG 6000), with the following levels of water potential: zero, -0.3, -0.6 and -0.9MPa. Seeds from each water potential treatment were placed to germinate under four temperatures: 20, 25, 30 and 35°C. The physiological quality of the seeds was evaluated by germination test, first counting and speed of germination index. It was concluded that water potentials lower than or equal to -0.3MPa, and temperatures equal to or greater than 25°C caused a reduction in the speed and percentage of germination of lettuce seeds. The water potential of -0.9MPa and/or the temperature of 35°C inhibited seed germination of bare and pelleted seeds. Bare seeds had larger reduction in physiological quality than pelleted seeds when exposed to hydric and thermal stress.
-The objectives of this work were to verify the efficiency of the hydroponic system in the detection of genetically modified (GM) soybean seeds and to establish a detection protocol in the hydroponic system. Seed samples of the two genotype were used, one genetically modified and the respective non-genetically modified (non-GM) parent. Five assays were performed to establish the detection protocol, in assays I and II the seed pre-germination was performed and later the seedlings were placed in recipients containing nutrient solution and then transferred to herbicide solution, (the concentrations used were 0; 0,12; 0,24; 0,36; 0,48% of the equivalent glyphosate acid), and finally, the seedlings were returned to the nutrient solution. In assays III, IV and V the seeds were placed directly in recipients containing herbicide solution and then the seeds were transferred to nutrient solution. The evaluated parameters were percentage of normal seedlings, seedling, root and hypocotyls length and number of secondary roots. The recommended protocol consisted of the seeds permanence in contact with herbicide solution to 0.12% of the equivalent glyphosate acid for four hours, followed by the transfer of the seeds to nutrient solution until completing five days, using as evaluation parameter the seedling length and the presence of CEP 96010-900. Pelotas -RS.
Light is considered a factor that influences the seed germination of many weed species, and it can signal whether the environmental conditions are favorable or are not favorable for germination. We aimed to study if there is an influence of light quality and dormancy overcoming in seed germination of Echium plantagineum L. We carried out a 2 x 6 factorial experiment, with and without dormancy overcoming with potassium nitrate followed by immersion in gibberellic acid; six light qualities, obtained through the light filters: blue, green, red, far-red, white light and absence of light. The evaluations performed were germination speed index (GSI), average germination time (AGT), germination at the four and 14 days after seeding (DAS), accumulated germination and relative frequency of germination. We observed significant interaction among the light qualities and seed dormancy overcoming or not for the studied variables. There was no significant effect of light qualities, in the evaluated variables, when performing dormancy overcoming, presenting germination above 90% in all the light qualities. However, without dormancy overcoming, we observed greater GSI, germination at four and 14 DAS for the red light filter with 5, 4, 29 and 45%, respectively. When the seeds were submitted to the absence of light, and without dormancy overcoming, there was only 7% of germination at 14 DAS. The seeds of E. plantagineum presented greater germination under incidence of red light, without dormancy overcoming, being classified as preferably positively photoblastics, provided that the dormancy is not overcome.
Safflower (Carthamus tinctorius L.) presents a high susceptibility for the attack of pathogens, resulting in low productivity of seeds. Thus, we aimed to evaluate the physiological and sanitary quality of safflower seeds submitted to different treatments. The experiment was conducted in the Floricultural Sector and in the Didactic and Seed Research Laboratory, in completely randomized design, with 4x9 (lots of seeds and treatment of seeds), with four repetitions. The lots of seeds were cultivated in the crop 2017/2018, the sowing occurred in the first fortnight of each season of the year (autumn, winter, spring and summer). After collected, the lots were stored in cold chamber with average degree of humidity of 9.0%. The treatments of seeds were constituted by: control, thermotherapy via humid heat, thermotherapy via dry heat, Trichoderma harzianum, chemical fungicide with active ingredients of Carbendazim+Thiram, Metalaxyl-M+Fludioxonil and Carboxin+Thiram, vegetal extracts of Dendranthema grandiflora and of Melia azedaeach. We evaluated the seeds treated by the standard test of germination, length and mass of seedlings, emergence and sanity. We observed that all the tested treatments benefit the safflower culture, promoting improvement in its germination, with efficient establishment of seedlings in the field. At the same time that was carried out the infestation control of the pathogens on the same, among the treatments we highlight the chemical fungicide with active ingredient Carbendazim+Thiram.
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