Impacts Of Free Air CO₂Enrichment On Green Beans

From the IPCC report, we know that by the middle of this century the global atmospheric CO2concentration than current will increase the concentration of50%. CO2is the raw material of plant photosynthesis, the concentration of CO2will promote the photosynthesis of plants, then influence the growth and yield of crops. The changes in soluble sugar content and the photosynthesis and yield are closely related to. The concentration of CO2will also have an effect on morphological index of crop. Elevation of CO2on plants has been a lot of reports, but the results of the previous studies are mostly based on open-top chamber or greenhouse studies, Using the FACE system on crop yield reported mainly for rice, wheat and other grain crops, only Hao Xingyu, using the FACE system to green bean growth were studied in pot experiment. In this study, the FACE system of green bean field trials is in Changping Experiment Station of the Chinese Academy of Agricultural Sciences.we will plan to study that the soluble sugar content of green bean leaves, photosynthesis, photosynthetic pigment, morphological index, biomass and yield how to change when atmospheric CO2concentration is elevated.The results show that:1. The effect of elevated CO2on leaf soluble sugar content of green bean function is not obvious. At the blossom period of green bean, chlorophyll a and total chlorophyll is increased, carotenoid content had no significant change.2. Leaf net photosynthetic rate (Pn) of green bean is increased, stomatal conductance is decreased, transpiration rate did not change significantly, use of water is increased when atmospheric CO2concentration is rised,.3. At the blossom period, when the atmospheric CO2concentration is rised, the area of green bean3leaf is increased, the plant height of green bean, node number, branch number had no significant effect, at the harvest period, green bean stem diameter is increased. When the free air CO2concentration is increased the root length has no significant effect, but the blossom period large nodule number and nodule weight increased significantly.4. Elevated free atmospheric CO2concentration did not significantly affect weight of green bean leaves. In the pod, Elevation of CO2significantly increased the green bean stem weight, and green bean pod weight at the harvest period. Elevation of CO2did not significantly affect weight of green bean root, but significantly increased the nodule weight of blossom period. Elevation of CO2will increase the biomass of green bean.5. Elevation of CO2increased the green bean biomass and yield significantly, an increase of11.57%and14.22%. Elevation of CO2had no significant effect on green bean harvest index.