Analytical procedure for estimation of the assimilation cell phase CO_2 mass transfer coefficient of crop leaf from experimental measurements of the net photosynthetic rate

摘要

Analytical solutions for the CO_2 concentration profile C_A (z_1 t) and CO_2 mass transfer coefficient k_L within the assimilation cell phase of the crop leaf in the net photosynthesis process were obtained by the concept of “rate of process” in the engineering science.To solve the CO_2 mass transfer problem of the crop leaf in net photosynthesis, CO_2-H_2O equilibrium at the assimilation-aerenchyma tissue interface within the crop leaf, Henry's Law, was introduced and the net photosynthetic reaction was approximated by a pseudo-1st order irreversible form.Simultaneously, in order to estimate quantitatively k_L and the over-all gas phase CO_2 mass transfer coefficient k_G from the practical observed results of the net photosynthetic rate R_A, the graphical method and its procedure were proposed, using the results of R_A for “rice” presented by Yabuki (1992). The summary is as follows:1) CO_2 mass transfer of a crop leaf in the photosynthesis process is a gas absorption-reaction. It is also a diffusion phenomenon in a gas-liquid binary system and the mechanism of CO_2 absorption may be represented schematically by a “two-film penetration diffusion model”. 2) Analytical solutions and the graphical method are available for evaluation of k_L and k_G from R_A observed in the field. These basic analytical procedures for gas absorption engineering are useful to obtain the correlation of the net photosynthesis reaction rate constant k_1 with R_A and CO_2 mass transfer coefficients.3) k_1 is a primary characteristic parameter to evaluate the net photosynthetic ability of the crop. The over-all assimilation cell phase CO_2 mass transfer coefficients, k_L, k_L and k_G depend on k_1. Therefore, to estimate a valid R_A or an appropriate net photosynthetic ability of the crop leaf, CO_2 mass transfer coefficients correlated with k_1 must be used.