Research Of Observation And Simulation Winter Wheat Stomatal And Canopy O₃ Absorbed Flux

Ozone as one of main pollutant in troposphere, through the stomatal and nonstomatal into the plant, impact of leaf photosynthesis, change the leaf’s blade shape and inhibit the normal growth of crop, Threat to crop production, this research through the OTC and flux box on the winter wheat measure stomatal O3 absorption and canopy O3 absorption fluxes, and Yangtze river delta region of winter wheat stomatal conductance and stomatal O3 absorption flux is simulated. The main results were as follows:(1) The test results show that under O3 stress, the stomatal conductance decreased,and the higher O3 concentration, stomatal conductance reduced more significantly, the overall trend is that CK>T1>T2, the max stomatal conductance is 0.289 mmolO3/m2, treatment T1 treatment group compared with CK, the stomatal conductance of drop is 3%-36.5%, in the booting stage and late grouting,Tl treatment group of stomatal conductance was significantly lower than CK group (p<0.05). T2 treatment group compared with CK the stomatal conductance of drop is 11.4%-46%. At 8:30-10:00 in the morning,the main limiting factors of stomatal conductance and photosynthetic active are radiation and temperature, at 10:00-17:00, impact the stomatal conductance the main limit factor is the water vapor pressure.(2) The first 40 days in the experiment, T1 treatment group of winter wheat stomatal absorption flux increased rapidly, the 30th day, thus O3 absorption flux is no more increases gradually. because of the high O3 concentration, the 25th days, T2 treatment group stomatal O3 absorption fluxes increased more rapidly than T1,03 absorption flux is no more increases, the total O3 absorption flux CK< T1< T2, CK absorption fluxes is 1.7 mmol/m2, T1 absorption fluxes is 12.2 mmol/m2, T2 absorption fluxes is 12.2 mmol/m2. When winter wheat effective absorption flux reach 10mmol/m2, the T1、T2 group of respectively dry matter loss of 9.1% and 12.6%.(3) Different growth period of winter wheat, canopy O3 absorption fluxes change range from 2.0 to 12.2nmol/m2s, during the all growth period of winter wheat, daily mean value of the winter wheat canopy O3 absorption flux changes presents unimodal change. A maximum daily mean value 7.4 nmol/m2s in filling period5in mature period, daily mean value reduced to a minimum, the minimum canopy O3 absorption fluxes is 3.8 nmol/m s. In different weather periods, sunny days’canopy 03 absorption fluxes is greater than the cloudy.(4) In March、April and May, the Yangtze river delta region winter wheat stomatal conductance and stomatal O3 absorption flux is simulated, in March, stomatal conductance is less than in April and may. In may, winter wheat is gradually mature, stomatal conductance gradually is reduced, simulation results show that the largest stomatal conductance maximum 210 mmolO3/m2s in the April, Winter wheat O3 cumulative absorption flux is decided by environment ozone concentrations and stomatal conductance, the calculation results of winter wheat O3 cumulative absorption maximum flux in April, the maximum value tendency for 12.0 mmol/m2.