Daily Simulation of Potential Dry Matter Production of Annual Field Crops in Tropical Environments

Abstract

This paper describes the modeling procedures activated when assessing potential biomass production using the Daily Crop Growth Simulator (DAICROS). Under optimal water and nutrient supply, the main physiological processes governing crop growth are photosynthesis, respiration, and leaf expansion. Simulation of the gross photosynthesis rate involves, among others, assessment of the maximum photosynthesis rate at light saturation, description of the photosynthesis light response of a fully developed canopy, and simulation of the leaf area index (LAI). Within the respiration module, maintenance respiration losses are quantified together with the conversion efficiency of the net primary assimilates into crop dry matter (DM), reflecting growth respiration losses. Leaf growth is simulated using a simplified model based on the LAI at maximum growth rate and the characterization of four leaf growth stages including fast linear growth during the vegetative stage and exponential decay at the end of the crop cycle. Input requirements include daily records of temperature and sunshine duration and crop parameters to be provided by local experts or the international literature. Both input requirements and output returns are illustrated by a case study simulating potential DM production of common bean (Phaseolus vulgaris L.) in Kigali, Rwanda. Sensitivity analysis and comparison of the simulated potential yields of five annual crops with field, literature, and alternative crop growth model outputs proved successful for model validation in the tropics and subtropics. Modeling capacity, functionality, and expendability of DAICROS surpass the performance of the worldwide operational crop growth model for land evaluation purposes developed by Tang.