MODELING DRY MATTER PRODUCTION FROM Photosynthesis and Respiration.

Simulation models for plants should simulate the production of dry matter of a whole plant through modeling principally leaf photosynthesis and respiration. Normally, leaf photosynthesis is used to create a pool of carbohydrates, which then are used by respiration. Respiration uses the energy released from the pool for building new plant structures, for tissue maintenance, general metabolism, tissue degradation and assimilation and senescence, and an amount lost by heat or litter. It could be easy to calculate the production of dry matter just by reducing the carbohydrates pool by the modeled respiration and transforming the remaining ones into dry matter. But, at the most cases, the simulated results are not similar to the observed data. The inconsistency is probably produced by photosynthesis and respirations processes yet unknown and unmeasured. As these unknown processes are not yet considered some engineering must be done. Still some coefficients should be used to equal the observed and the simulated data. Photosynthesis and respiration were measured through all development phases of evening primrose plants. Which were grown in pots and three different nitrogen fertilizations were applied. Photosynthesis was modeled using the Thornley quadratic equation. Models for respiration were built considering development, nitrogen fertilizations and the day and night cycle. Using these mathematical models the accumulation of dry matter was simulated. The general Paradigm was considered for the creation of a flow diagram in order to simulate dry matter. Maintenance, litter and senescence were all considered in the flow diagram. The built model was useful for modeling evening primrose dry matter accumulation.