Silvio Lopes Teixeira

Influence of NaClO on nutrient medium sterilization and on pineapple (Ananas comosus cv Smooth cayenne) behavior

A new protocol for the preparation and sterilization of media with sodium hypochlorite was tested for in vitro culturing of pineapple shoots. Total active chlorine concentrations equal to or higher than 0.0003%, as well as other asepsis procedures, provided complete sterilization of the medium. At a total active chlorine concentration of 0.0003%, pineapple shoots more than doubled both their biomass and the number of new shoots.

Utilização de hipoclorito de sódio na esterilização de meio de cultura para multiplicação in vitro de Eucalyptus pellita L.

Lately it has been observed a great interest in the research area of plant tissue culture in discovering new alternatives leading to cost reduction of the plants produced in commercial laboratories, in order to turn this alternative of plant propagation more economical. A potentially promising alternative for this reduction of costs, but which has not been receiving the due attention, is the possibility of substituting the autoclaving technique to a more economical one. With this purpose, two tests were carried out, using a new protocol of medium preparation, which consisted of the chemical sterilization of all the utensils used in the preparation and packaging of the culture medium as well, associated to the addition of the sterilizing agent to the medium, in different concentrations. The objective of the first test was to observe the influence of different concentrations of NaClO added to the culture medium, on its sterilization. The second test aimed at verifying the reaction of the Eucalyptus pellita tissues to different concentrations of NaClO in the culture medium. The addition of NaClO to the culture medium, equal or higher than 0.0005% in the fist test and of 0.005% in the second one, allowed complete sterilization of the medium, without observing any damage to the Eucalyptus pellita tissues, even when they were grown on culture medium containing up to 0.009%, the maximum concentration tried. The results showed the viability of eliminating the autoclave for the sterilization of culture media.

Substituição de nitrato de potássio (PA) por salitre potássico no preparo de meio de cultura de tecidos vegetais esterilizado com hipoclorito de sódio

A aquisicao de nitrato de potassio PA, para qualquer finalidade, depende de autorizacao do Ministerio da Defesa, o que resulta em dificuldades na sua aquisicao. Com a finalidade de estudar a possibilidade da substituicao desse reagente por outro produto encontrado livremente no comercio, foi conduzido um experimento onde se testaram varias concentracoes de salitre potassico em comparacao com o nitrato de potassio PA, como componente dos sais de MS. Utilizou-se o produto granulado MURER® nas seguintes concentracoes (g L-1): a) 7,0; b) 7,4; c) 7,8; d) 8,2. Foi adicionado um tratamento-controle, com o KNO3 PA, conforme aparece nos sais de MS (1,9 g L-1), sendo a especie testada a fafia, a partir de segmentos nodais. O meio de cultura constituiu-se dos sais de MS, vitaminas de White, 30 g L-1 sacarose, 2,0 mg L-1 acido indol butirico, 2,0 mg L-1 acido naftalenoacetico, 2,0 mg L-1 benzilaminopurina, pH 6,0 + 0,1 e 1,5 g L-1 Phytagel® como gelificante. O numero medio de ramos formados para todos os tratamentos foi inferior ao do tratamento-controle; mas, em compensacao, o comprimento medio deles foi superior, tambem em todos os tratamentos, sendo que o comprimento total de ramos na menor concentracao de salitre, atingiu 17,0 cm, enquanto no tratamento-controle foi de 12,6 cm. A media da biomassa seca foi de 68,3 mg para a menor concentracao de salitre e de 50,0 mg para o tratamento-controle. A analise dos resultados indicou ser vantajosa a substituicao do nitrato de potassio PA pelo salitre potassico.

Cultivo in vitro de Sequoia sempervirens L. em meio de nutritivo esterilizado com hipoclorito de sódio

The autoclaving used for sterilization of glassware, culture media and surgical materials in laboratory is a costly operation, due to the high cost of the equipment and the equally high consumption of energy. For these reasons, the substitution of this sterilization technique for another less costly one, such as chemical sterilization, would be highly desirable. The present study aimed to compare the techniques of sterilization of plant tissue culture media with sodium hypochlorite and that of autoclaving, in Sequoia sempervirens culture, in order to develop a less costly technique in the sterilization of glassware and nutrient media for plant tissue culture. In the trial with Sequoia sempervirens , the concentrations of sodium hypochlorite added to the culture media were (w/v): 0% (autoclaved); B) 0.002%; C) 0.003%; D) 0.004% and E) 0% (without autoclaving). It was observed that the concentrations equal to or higher than 0.003% of total chlorine added to the nutrient media resulted in complete sterilization, as well as in plants with larger numbers and shoots lengths.

Influence of disinfestation and osmotic conditioning on the germinating behavior of australian royal palm (Archontophoenix alexandrae)seeds

The technique of Osmotic Conditioning, which consists of partial and controlled hydration of the seeds, has obtained success with various species of seeds, increasing the germinating span and tolerance to the adverse conditions of the environment, and has also reduced the time elapsed between sowing and the emergence of the plants. Associated to ideal storage conditions, the treatment has increased the performance of the seeds of tropical wood species. Aiming at studying the germinating environment and the effect of osmotic conditioning on the germination of seeds of the Australian Royal Palm tree, two experiments were performed. The first one evaluated the effect of disinfestation of the seeds of the Australian Royal Palm tree with NaClO. The treatments applied were: 0.5% sodium hypochlorite, exposure periods of 5, 15, 30, 45, 60, 90, 120 and 240 minutes, and the fungicide Captan, as control. The treatments with NaClO did not differ in relation to the final percentage of germination and to the germination speed index, and did not differ from the treatment control. The second test evaluated solutions with the following osmotic potentials: 0.0MPa (pure water), -0.4MPa, -0.6MPa and -0.8MPa, exposed for the periods of 10 and 20 days. The final percentage of germination did not differ among the treatments. The seeds hydrated in pure water for a period of 20 days showed a germination speed index significantly superior to the other treatments, and they did not show significant differences among themselves.