Studies On Photosynthesis And Respiration Characteristics Of Grape Plantlet In Vitro

Through the experiment on the Red Globe grape plantlets, the effects of temperature, light intensity, light quality, CO2, and sucrose concentration in medium on photosynthesis and respiration of a leaf and plantlets were studied. Here are the results of the experiment:1. The leaves on the higher position had the lower value of Pn but the higher Rd, conversely, the leaves on the lower position had the higher value of Pn but the lower Rd. CO2 could both enhance the photosynthesis rate of leaves and restrain respiration rate of them. It was clearly observed that the value of Pn of leaves increased with the light intensified; It was also seen that the Rd of leaves tended to increase with the temperature rising and that the Pn increased first and then showed a tendency to decrease. Compensation point of CO2 of leaves in different leaf positions increased with the temperature increasing.2. The culture conditions such as the temperature, light intensity and CO2 had the same effect on the photosynthesis and respiration of colony and a single leaf. When the temperature was in 25℃, the photosynthesis rate of plantlets was at the highest; when the temperature reached 35℃, the plantlets died. The respiration rate increased with the temperature increasing. When the light intensity was within 40-60 umol m -2 s-1, grape plantlets could effectively photosynthesize, but the value of Pn was low.3. The grape plantlet could grow on the medium that didn't contain sucrose, and the increase of CO2 concentration could enhance the growth of the plantlets effectively. Under the suitable culture conditions, the net photosynthesis rate of single leaf and colony are all positive. So the grape plantlet belongs to the autotrophic type.4. To some degree the growth and development of the grape plantlets relied on carbon. It was obvious that the growth of the plantlets was enhanced when addingsucrose into the medium and increasing the CO2 concentration of the growing environment of the plantlets. But on one hand the added carbon decreased the net photosynthesis, on the other hand it enhanced the respiration of plantlets.5. Grape plantlets could absorb 47.28% ~ 55.40% sucrose of the medium, after increasing CO2 concentration, the rate at which the plantlets absorbed the sucrose decreased to 38.65 % ~ 43.32%.6. Under different light qualities, the photosynthesis rates of grape plantlets were quite different. In the white light and red light, plantlets could photosynthesize effectively, while in yellow, green and blue lights, the plantlets could not photosynthesize effectively. The plantlets cultured under the different light qualities could photosynthesize effectively in white light.7. The different lights have the different effects on inducing the grape tissue and organ to differentiate: The red light could enhance the root differentiation and growth of the grape plantlets and induce the ex-plants to produce a lot of red calluses, while the other lights could only induce the ex-plants to produce the white calluses.8. In the course of domesticating, the extent to which the stoma of the grape plantlets expanded gradually decreased, the transpiration rate greatly reduced, and the saturating point rose gradually, the highest net photosynthesis showed the tendency to increase.