ISHS Acta Horticulturae 530: International Symposium on Methods and Markers for Quality Assurance in Micropropagation
QUALITY BIOMASS PRODUCTION VIA PHOTOAUTOTROPHIC MICROPROPAGATION |
| Authors: | S.M.A. Zobayed, F. Afreen, T. Kozai |
| Keywords: | acclimatisation, multiplication, photomixotrophic, scaled-up vessel, transplants |
| Abstract:
The commercial use of conventionally micropropagated plantlets is often undermined by their poor physiological quality and growth. A substantial percentage of plantlets cannot survive or cannot grow fast and vigorously after transplantation in the ex vitro conditions. This limits the possible prospects of this unique propagation technique. Plantlets grown under conventional micropropagation system (with use of 20 – 30 g l-1 sucrose in the medium and airtight vessels) are often characterized by non-functional stomata and limited epicuticular wax deposition on the leaves. Thus, immediately after transplantation, rapid water loss due to uncontrolled transpiration occurs followed by wilting. These effects are probably due to the prolonged exposure of the plantlets to high relative humidity in vitro (> 95 %) and low CO2 concentration and photosynthetic photon flux in the culture vessels during the photoperiod. The presence of sucrose in the medium and the accumulation of ethylene in the vessel may also play a role. The photoautotrophic micropropagation system (without any sucrose in the nutrient medium and with enriched CO2 and high photosynthetic photon flux), especially under forced ventilation, has been proved to produce morphologically superior and physiologically normal quality transplants. Plantlets grown in vitro under photoautotrophic conditions show high net photosynthetic rate, enhanced shoot and root growth and shortened multiplication period and the leaves contain functional stomata and high wax content. These plantlets exhibit less water loss after transplantation, as a result leaves do not wilt and grow fast even without any special ex vitro acclimatization. In photoautotrophic micropropagation, humidity is controlled (< 90 %) and the CO2 concentration is raised and ethylene can not accumulate simply due to increased air exchange rate of the culture vessel. Our recent research on the scaled-up vessel with forced ventilation system and on the aseptic culture room as an alternative for many large culture vessels for photoautotrophic micropropagation is introduced in this article. | |
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