ABSTRACT
ABSTRACT One of the major drawbacks of this final disposal technique is leachate production, which occurs due to the degradation of organic matter and rainwater percolation. The leachate composition is quite varied, with high organic load and various compounds that may be toxic to the environment. To reduce the polluting potential of the leachate, it must be subjected to an appropriate treatment. Biological treatments are widely used in the treatment of leachate, although these technologies have some drawbacks. As an alternative to conventional biological treatments, rotating biological reactors are used. The objective of this study was to determine the efficiency of a pilot scale rotating biological reactors in the removal of biochemical oxygen demand, chemical oxygen demand, and phosphorus from the landfill leachate. Effluent toxicity and rotating biological reactors's ability to remove this toxicity were also verified by calculating the germination index of lettuce (Lactuca sativa) and cucumber (Cucumis sativus) seeds. The reactor showed an average efficiency of 75.99% of biochemical oxygen demand removal, 33.53% of chemical oxygen demand removal, and 16.04% of phosphorus removal. In fact, the cucumber and lettuce seeds proved sensitive to the toxicity of the effluent. For crude leachate, the germination index values of lettuce and cucumber were 13.28 and 49.61%, respectively. In this study, rotating biological reactors obtained a good efficiency in the removal of toxicity from leachate. The germination index of the seeds for the treated effluent was 60.9% for lettuce and 82.49% for cucumber.
RESUMO Diante do crescimento populacional acelerado e do desenvolvimento econômico, grande quantidade de resíduos tem sido gerada nos grandes centros urbanos. Esses resíduos devem ser coletados e dispostos adequadamente, sendo os aterros sanitários os locais mais adequados para a sua disposição. Um dos grandes inconvenientes dessa técnica de disposição final é a produção de um líquido lixiviado, proveniente da degradação da matéria orgânica e da percolação da água da chuva. A composição do lixiviado é bastante variada, com elevada carga orgânica e diversos compostos que podem ser tóxicos ao meio ambiente. Para determinar a toxicidade do lixiviado são amplamente utilizados testes fitotoxicológicos, como o índice de germinação de sementes. Com o intuito de reduzir o potencial poluidor do lixiviado, este deve ser submetido a um tratamento adequado. Tratamentos biológicos são bastante utilizados, mas possuem algumas desvantagens. Como alternativa aos tratamentos biológicos convencionais, surgem os reatores biológicos rotatórios. O objetivo deste estudo foi determinar a eficiência de uns reatores biológicos rotatórios em escala piloto na remoção da demanda bioquímica de oxigênio, da demanda química de oxigênio e de fósforo do lixiviado do aterro. Também foi verificada a toxicidade do efluente e a capacidade dos reatores biológicos rotatórios para remover essa toxicidade por meio do cálculo do índice de germinação de sementes de alface (Lactuca sativa) e pepino (Cucumissativus). O reator utilizado neste trabalho obteve eficiência média de 75,99% de remoção de demanda bioquímica de oxigênio, 33,53% de remoção de demanda química de oxigênio e 16,04% de remoção de fósforo. As sementes de alface e pepino mostraram-se bastantes sensíveis à toxicidade do efluente. Para o lixiviado bruto, os índices de germinação da alface e do pepino foram, respectivamente, 13,28 e 49,61%. Neste estudo, os reatores biológicos rotatórios obtiveram boa eficiência na remoção da toxicidade do lixiviado. O índice de germinação das sementes para o efluente tratado foi de 60,9% para a alface e de 82,49% para o pepino.
ABSTRACT
Objective: To investigate the effects of single salt stress on seeds germination and seedlings growth of Amygdalus mongolica. Methods: The single salt stress condition was simulated with various concentration of NaCl, Na2SO4, and CaCl2 solutions; And the indexes of seeds germination and seedlings growth was tested under this condition according to the requirements of paper bed germination test. The study material used in this study was the seeds (without endocarp) of Amygdalus mongolica which was an endangered plant species from the Nature Reserve of Qilian Mountain. Results: The germination rate of seeds, the fresh weight, and dry weight of the seedlings increased with the increase of the solution concentration when the concentration is in the range of 0.02-0.04 mol/L; The three indexes mentioned above decreased with the increase of the solution concentration when the concentration was in the range of 0.06-0.18 mol/L; And this correlation was consistent among all the three salts used in this study. Seeds germination index, seeds vigor index, saturated moisture content of the seeds, seedlings height, length of primary roots, root length, total number of the secondary roots, saturated moisutre content of the roots, and the root dry weight of the seedling decreased significantly when the condition of the salt stress was intensified (P < 0.05). Conclusion: The seeds of A. mongolica is very sensitive to the changes of the salt concentration and the results showes that when NaCl and CaCl2 solution is used, P50 concentration for seeds germination is 0.12 mol/L, and for seedling growth is 0.10 mol/L; When Na2SO4 solution is used, the P50 concentration for seed germination and for seedling growth is 0.10 mol/L and 0.06 mol/L respectively. Stress of high concentration of signal salt could make some seeds to be dormant, thus the viability of those seeds could be remained and the germination rate of the seeds which failed to germinate under the condition of single salt stress was up to 82%-89% after rewatering.
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OBJECTIVE:To select the optimum conditions for germination test of Astragalus membranaceus seed and provide reference for the formulation of testing rules of A. membranaceus seed. METHODS:First,the dormancy of A. membranaceus seeds were broken by soaking seed with 98% H2SO4 for 30 min and 35 ℃ warm water for 9 h,then treated with different temperatures of germination,different germinating beds and light conditions. Different treatment methods were evaluated by germination rate, germination potential and germination index. RESULTS:With the increase of temperature,germination rate,germination potential and germination index decreased. At 30 ℃,germination rate,germination index,and germination potential were significantly low-er than those of seed with other treatments,in which the germination rate was the highest at 15℃;but there wasn’t significant dif-ference in germination rate of 15 ℃ and 20 ℃. There were no significant differences in germination rate of different germination beds,but sand bed could restrain bacterial growth well. Under both light and dark conditions,seed could normally germinate. The appropriate condition of A. membranacus seed germination was at 15 ℃,sand bed and dark. The germination rate,germination po-tential and germination index were(98.5±0.65)%,(85.5±0.87)%and 175.8±2.31,respectively. Meanwhile,the germination pe-riod was only 4 days. CONCLUSIONS:Suggested quality control method of A. membranaceus seed is that at 15 ℃,sand bed and dark. The second day of germination as initial counting time and forth day as the last counting time are used to calculate germina-tion index. This method is easy and controllable. It also has short germination period and high germination rate.
ABSTRACT
An investigation was made to see the salt tolerance of 10 weed species of rice. Properly dried and treated seeds of weed species were placed on 9 cm diameter petridishes lined with Whatman No. 1 filter paper under 6 salinity regimes, viz. 0 (control), 4, 8, 16, 24 and 32 dS m-1. The petri dishes were then kept in germinator at 25±1.0oC and 12 hr light. The number of germinated seeds were recorded daily. The final germination percentage, germination index (GI), seedling vigour index, mean germination time and time for 50% germination were estimated. Root and shoot lengths of the weed seedlings were measured at 20 days after salt application and relative growth values were calculated. Results revealed that salinity decreased final germination percentage, seed of germination as measured by GI, and shoot and root length in all the species. Germination of most of the weed seeds was completely arrested (0) at 32 dS m-1 salinity except in E. colona (12%) and C. iria (13.9%). The species C. iria, E. colona, J. linifolia and E. crusgalli showed better germination (above 30%) upto 24 dS m-1 salinity level and were regarded as salt-tolerant weed species. J. linifolia, F. miliacea, L. chinensis and O. sativa L. (weedy rice) were graded as moderately tolerant and S. zeylanica, S. grosus and C. difformis were regarded as least tolerant weed species.
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A obtenção de cariopses de cana-de-açúcar por meio de cruzamento de parentais é de primordial importância para os programas de melhoramento de cultivares. Objetivou-se, neste trabalho comparar o ambiente de germinação de cariopses da casa de vegetação do Programa Cana IAC com um ambiente de condições controladas, a fim de avaliar sua eficiência, no período de 30/09 a 09/10/2004. Foram desenvolvidos dois experimentos, em delineamento experimental de blocos casualizados com quatro repetições, em Jaú, SP. Um deles foi montado sob condições de laboratório em câmara de germinação e outro em casa de vegetação em condições não controladas, sendo cada tratamento constituído por 100 cariopses por repetição, provenientes de seis cruzamentos. Foram realizadas avaliações do índice de velocidade de germinação (IVG), da porcentagem ( por centoG) e dos dias para emergência (DE), em intervalos de 24 horas, após a instalação dos testes. A massa de 100 sementes de cada cruzamento também foi avaliada com o propósito de verificar sua influência nos demais atributos da germinação. Os resultados foram submetidos à análise de variância e a comparação de médias foi feita pelo teste de Tukey, a 0,05 de significância. A massa de 100 sementes foi diferente entre os cruzamentos, e interferiu, de maneira geral, nos atributos IVG e por cento G. Concluiu-se que a casa de vegetação utilizada pelo Programa Cana IAC proporciona porcentagens de germinação semelhantes às da câmara de germinação, porém condições controladas favorecem o IVG e os DE.
The production of true seeds of sugarcane through parental crossing is primordial for the breeding programs of cultivars. With the objective of comparing the efficiency of the environment greenhouse used for seed germination in the IAC Sugarcane Program with an environment with controlled conditions (germination chamber), two experiments were carried out in a completely randomized block with four replicates of 100 seeds each, in Jaú (SP), from 09/30 to 10/09/2004. In both places the treatments were composed of seeds from six crossings. The evaluations accomplished were speed of germination index (SGI), germination percentage ( percent G) and days for emergence (DE) in 24 h intervals after set up treatments. The mass of 100 seeds of each crossing was also evaluated with the purpose of measuring its influence on other germination attributes. The data were submitted to the analysis of variance and averages were compared by the Tukey test at 0.005 significance. The weight of 100 seeds differed among the crossings, and, in general, it interfered with the attributes SGI and percent G. It was concluded that the greenhouse used by the IAC Sugarcane Program provides germination percentages similar to the germination chamber; however, controlled conditions improve SGI and DE.