Plant tissue culture is carried out in sterile conditions in vitro. Culture vessels are generally closed with a suitable cap in order to prevent contamination. The relative humidity is often close to 100% in vitro, and microplants are not apt to photosynthesis activity due to light, gas exchange and dependence on mineral and organic nutrients in culture conditions. As a consequence, microplants leaves have only thin cuticular layer and their stomata are always open. Usually there should be a phase of gradual adaptation to the ex vitro conditions as a requirement for plantlets to experience stomata operation, water conduction from roots and photosynthesis. This is a critical phase in the micropropagation, all the more considering the laboratory low relative humidity (~ 35%) and its lighting and thermal fluctuations, resulting in high loss. Placing sugar beet microplants roots in water for a better establishment in pot has been already suggested (Ehsani Moghaddam[1], 1999). A water culture device equipped with aeration system designed and tried in 2001, proved to have positive effects on acclimatization of microplants preventing any growth depression to occur and consequently large number of plants were potted without loss. These results were achieved by a research sponsored by National Scientific Research Council. The inclusion of water culture use in ex vitro adaptation phase of micropropagation cycle is presented here as an innovation for which scientific, technical, educational and commercial outputs are possible. Thanks are due to the SBSI board of directory for their encouragement and to our colleague Mr. Abbas Ghassemi for his water culture system equipment set-up.
)