A Simulation Study of Surplus Productivity as Influenced by the Photosynthesis and Respiration Rates of a Single Leaf

A microcomputer simulation was used to demonstrate the overall behavior of surplus production, which was calculated from Kuroiwa's (1966) production formula, as influenced by the photosynthesis rate (p0) at the saturated light and dark respiration rate (rA) for a single leaf.The effect of p0 and rA upon surplus production (Ps) was illustrated as a contour map and three-dimensional diagram as a function of leaf area index (A) and light attenuation coefficient (K). A maximum in this type of A-K-Ps relation was a common feature, that is, there existed an optimum light attenuation coefficient (Kopt) at which the highest surplus production (Ps, top) could be obtained among the maximum surplus productions (Ps, max).Being independent of any combination of p0 and rA values, it emerged from the simulation that the value of Ps, top remained constant as long as the rA/p0 ratio was held constant. The significance of the constancy predicted here is discussed in relation to crop and pasture production.