O_3,CO_2浓度及太阳光谱变化对作物光合作用影响的数值模拟研究

NUMERICAL SIMULATION OF THE INFLUENCE OF O_3,CO_2 AND SPECTRUM VARIATION ON THE PHOTOSYNTHESIS OF CROP CANOPY

对光合作用 蒸腾作用 气孔调节进行耦合 ,从生物化学尺度扩展至冠层尺度 ,发展了一个冬小麦冠层光合作用生态动力模式 ,模式考虑了O3,CO2 和光谱变化对作物光合的综合影响。利用美国光合作用实测资料对模式进行验证 ,叶片模式通过了相关显著性检验并具有较高的准确度。数值分析表明 :当O3 浓度由 0× 10 -9V/V上升至2 0 0× 10 -9V/V时 ,冠层光合速率下降 2 9%左右 ;当CO2 浓度由 330× 10 -6V/V上升至 6 6 0× 10 -6V/V时 ,冠层光合速率增加大约 37% ;当光谱比例系数由目前的 0 .5下降至 0 .4时 ,冠层光合速率将下降 2 7%左右。对于污染严重、易发生光化学烟雾的城郊附近 ,在阳光强烈的典型晴天 ,中午O3 浓度达到 2 0 0× 10 -9V/V时 ,即使气候条件不发生改变 ,CO2 浓度对作物光合作用的正效应也不足以弥补O3 浓度升高所造成的负效应 ,冠层光合速率将比目前干洁地区略有下降 ,如果进一步考虑光合作用有效辐射光谱成分下降至 0 .4左右 ,冠层光合作用将比目前的BASE值下降 35 %左右。

A leaf model was established for simulating photosynthesis of winter wheat based on characteristics of physiological ecology of plant, and then a canopy photosynthesis model was scrolled up from the leaf model. The influence of CO 2, O 3 and spectrum variation on canopy photosynthesis was fully considered in the model. Validation of the leaf model showed that the model could simulate photosynthesis rate of winter wheat in field fairly well. The simulation result by using the model indicated that: (a) When the concentration of O 3 increased from 0 ×10 -9V/V to 200 ×10 -9V/V, the canopy photosynthesis will decrease about 29% in contrast with the base value. The canopy photosynthesis will enhance about 37% when the concentration of CO 2 changed from 330×10 -6V/V to 660 ×10 -6V/V. The canopy photosynthesis declined with the debasement of spectrum coefficient according to the linear relation, which reduced about 27% with the spectrum coefficient varied from 0.5 to 0.4. (b) The canopy photosynthesis will be reduced about 35% in suburb, when the spectrum coefficient reduced to 0.4 and the concentration of O 3 increased to 200×10 -9V/V, even with a doubled CO 2 concentration and unchanged climatic scenarios.