The Comparison And Spatial And Temporal Distributions Of Stomatal Flux In Different Crops Under Ozone Stress

As one of the main atmospheric pollutants over Surface Layer, researches on the increasing surface ozone concentration and its impact on main crops have become the focus of every government and the public. This paper regards winter wheat and soybean as the research object, based on the field experiment, it is expected to obtain the data including ozone concentration, meteorological data, stomatal conductance and crop growth index and yield by continuous observation, stomatal conductance model is used and parameterized, according to O3 absorption flux model, we will analysis on the characteristics of stomatal flux in different crops under the ozone pollution. At the same time, the stomatal conductance and stomatal O3 absorption flux of winter wheat and soybean is simulated in Jiangsu Province. The main results were as follows:(1)In the experiment of winter wheat, the average of temperature, photosynthetic active radiation, relative humidity, water vapor pressure and O3 concentration is 26.06℃,706.89μmol·m-2·s-1,44.35%,2.34kpa, and 53.67ppb in open top chamber. In the experiment of soybean, the average of temperature, photosynthetic active radiation, relative humidity, water vapor pressure and O3 concentration is 32.23℃, 687.60μmol·m-2·s-1,37.54%,3.32kpa, and 57.15ppb in open top chamber. Meanwhile, the daily variation of meteorological factors and O3 concentration showed ascending-descending trend.(2) With the increase of O3 concentration, the plant height, leaf area, biomass and yield of winter wheat and soybean decreased and the effect of soybean is more serious.(3) Elevated ozone concentration can reduce stomatal conductance of crop leaf and stomatal conductance decreased with the increase of ozone concentration. Compared to the control group, soybean leaf stomatal conductance decreased more significantly.(4) Based on the boundary line technology, stomatal conductance model is parameterized according to the observational data. In the experiment of winter wheat, the total O3 absorption flux in ozone concentration of CK, 100ppb,150ppb was 6.42mmol03·m-2,12.27mmolO3·m-2,13.90 mmolO3·m-2 respectively. In the experiment of soybean, the total O3 absorption flux in ozone concentration of CK, 100ppb,150ppb was 14.46mmolO3·m-2,15.86mmolO3·m-2,16.69 mmolO3·m-2 respectively.(5) We compare the observed conductance and the simulated conductance. In the experiment of winter wheat, their relationship were established as the function that is y=1.2044x-15.116, y=1.20x-6.8, y=1.07012x-1.68347 respectively. In the experiment of soybean, their relationship were established as the function that is y=1.02831x+8.37158, y=0.97117x+20.84442, y=1.12616x-7.58398 respectively. It showed that the model was well simulated.(6) The ozone concentration gradually increased from early period to late period during the period of winter wheat and soybean growth in Jiangsu area. Average stomatal conductance of Winter Wheat is the middle stage> the later stage> the early stage. Average stomatal conductance of soybean is the early stage> the middle stage> the later stage. Winter wheat O3 cumulative absorption flux is the most during the middle stage, soybean O3 cumulative absorption flux is the most during the early stage. Throughout the whole growing period, soybean O3 cumulative absorption flux is bigger than winter wheat O3 cumulative absorption flux.