Adaptation of SUBSTOR for Hydroponic, Controlled Environment White Potato Production

SUBSTOR, a process-oriented crop growth and development field model included with DSSAT software, was modified for controlled environment hydroponic production of white potato (cv. Norland) under elevated carbon dioxide concentration. Modifications were primarily based on growth and phenological data obtained via in-house experiments in ebb and flood equipped growth chambers at Rutgers University. Results from published literature were also used for additional modification where appropriate. The adaptations made to SUBSTOR included adjustment of input files for hydroponic cultural conditions, calibration of genetic coefficients, parameter tuning such as for radiation use efficiency, and source code changes. The latter included accounting for the absorption of light reflected from the surface below the canopy, an increased senescence rate, adding a carbon (mass) balance to the model, and a modified response of crop growth rate to CO₂ concentration. Modified-SUBSTOR predictions were then compared with data from in-house experiments and Kennedy Space Center's Biomass Production Chamber.