Browsing by Author "Armstrong, J."

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    A humidity-induced convective throughflow ventilation system benefits Annona squamosa L. explants and coconut calloid
    (2007-02-08) Armstrong, J.; Lemos, E.E.P.; Zobayed, S.M.A.; Justin, S.H.F.W.; Armstrong, W.
    A simple apparatus is described for generating pressurized throughflow ventilation in plant tissue culture vessels. No pumps or gas-cylinders are required and the flow is driven by humidity-induced diffusion across microporous membranes. In the experiments described, pressurized flows of sterile humidified air were supplied at rates of up to 1 ml min 1 and these had beneficial effects on leaf survival and production in Annona cuttings and on calloid form in coconut. Ethylene (ethene) was removed more quickly from the pressure-flow ventilated culture vessels(/50 0-4-0-7 h) than from those aerated by diffusion through conventional polypropylene membranes (tm, 1-6-2-4 h). In Annona cuttings leaf production was greatly increased and ethylene-induced leaf fall considerably delayed when cultured with the forced as opposed to diffusion-based ventilation of the vessels. With throughflow ventilation, coconut calloid was more convoluted than under wholly diffusive aeration and had a smooth distinct epidermal surface and clearly denned sub-epidermal meristematic nodules. It resembled freshly initiated calloid from which regeneration of plantlets via somatic embryogenesis can be obtained. Under wholly diffusive aeration, calloid developed a rough, relatively undifferentiated surface, more haustorial (i.e. cotyledonary) in appearance, and characteristic of cultures where regeneration potential has been lost. It is suggested that other benefits of the pressurized throughflow ventilation may be the removal of volatiles such as ethanol and acetakl:hyde. the removal of excess carbon dioxide at night and its improved supply during the day, and sustained oxygen concentrations at levels close to atmospheric both night and day.