The effect of CO2 on photosynthesis by modeling and simulation

What is it about?

In photosynthesis, plant leaves use CO2 to synthesize organic compounds and energy by consuming light and water. CO2 concentration ([CO2]) in a green house may be a limiting factor for plant growth. Current green house CO2 control strategy usually depends on expert experience, which may control [CO2] in a moderate range but cannot make it optimal due to lack of considering plant photochemistry reactions. A state-space kinetic model structure covering major photosynthetic reactions as affected by CO2 is useful for [CO2] control strategy development in a green house because modern control theories are usually based on sate-space models. However, model structures on photosynthetic activities as affected by [CO2] in literature are usually either fitting experimental data mathematically or covering too many subtle reaction details in micro world, which are not appropriate for state-space control strategy development. In this work, a state-space kinetic model structure for photosynthesis was built, which describes the major reaction cascades of Photophosphorylation, Calvin cycle, and biophysical processes such as CO2 transport through the stomata under moderate [CO2] range without considering photorespiration. Simulations were performed with a large range of model parameters to demonstrate the effect of [CO2] on stable sugar production and the flexibilities of the developed model structure. The results clearly show whether increasing of CO2 will lead to more production of sugar or not in different scenarios. The model structure may be extended to cover other photosynthetic influence factors such as temperature by using the well known Arrhenius equation.

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Why is it important?

Facing with world-wide restriction of energy, pouring of population, huge variations in climate, and reduction of farming land, effective cultivation of grain seems to make great sense. To compensate the limitation of agriculture yield in wild land, green house plays an important role in modern agriculture especially for vegetable production. Sunlight and CO2 in atmosphere were the major resources to the growth of plants. The concentration of CO2 has a significant effect on photosynthesis, but the utilization of CO2 on agriculture did not reach the level of theory and refinement, especially for plant physiological based control in green house production. Therefore, the study inquiring into plants photosynthetic activities as affected by CO2 has its realistic value for the food crisis on 800 million people.

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