Study Of Photosynthetic Characteristics Of Orychophragmus Violaceus Plantlets In Vitro With CO₂ And Light

By engineering technique, plantlets in vitro with characteristics of equal growth, healthy development, no infection or a few infection and short period of acclimation ex vitro can be macro-propagated at low cost. In this paper, we have studied on photosynthetic characteristics of Orychophragmus violaceus plantlets in vitro with CO₂ and light, as presented bellow:1．On the base of completely analyzing performances of all the apparatus at present applied to detect plantlets in vitro of photosynthesis rate which used to be difficultly detected for the specific environment in which plantlets in vitro grow, leading no breakthrough has been attained, novel detection system for photosynthesis rate of plantlets in vitro was worked out, overcoming the flaws of existing apparatus and successfully performing the consecutive detection of rate with no fluctuation of its micro-environment.2．Using the apparatus we designed, the photosynthetic rate of Orychophragmus viohceus plantlets in vitro in culture stage was measured, the daily changes of photosynthesis rate of these plantlets radiated by different light sources and the process of performances of carbon dioxide in vitro with different concentrations and that of different light intensity were analyzed. As a result, we find that plantlets in vitro have no obvious phenomenon of midday depression of photosynthesis during the process of photosynthetic rate daily change.3．Optimal photosynthetic model of Orychophragmus violaceus plantlets in vitro was built combining plantlets in vitro photosynthetic characteristics studied by mathematics model and the culture environment, and the carbon dioxide compensation points and saturation points of the plantlets in vitro under radiation of different lights were found by investigating the effect of increasing concentrations of carbon dioxide using the photosynthetic model. And its CO₂ compensation point and CO₂ saturation point under different light have been educed as follow: Under the condition of 70μmol·m^-2·s^-1 of light intensity, the CO₂ compensation point and its saturation point of Orychophragmus violaceus plantlets in vitro are 347 and 3416μmol·mol^-1 of LED-red-light, 365 and 3110μmol·mol^-1 of LED-blue-light, 366 and 2563μmol·mol^-1 of LED-white-light, respectively. In the extent of photosynthetic effective radiation, when the intensity of this radiation increases CO₂ compensation point decreases while all of the maximum of CO₂ exchange rate, carboxylation rate, CO₂ saturation point and respiration rate increase. Consequently, the growth-model-based large culture box and its environment-automatic-control system were designed out, using the control strategy that the concentration of carbon dioxide in the box can be controlled by the amount of gas flux, the CO₂ enrichment in the mix cask by the gas pressure and the relative humidity in the box by closed-circuit gas dehydration circulation outside the box, thereby automatically and accurately controlling the concentration of carbon dioxide and relative humidity in the box.