2.3.1 Preset and uncertain parameters in GECROS
Before conducting the calibration procedure, key photosynthetic parameters in GECROS were preset with the values derived from our previous study (Wang et al., 2022). Meanwhile, phenological parameters, MTDV and MTDR, and parameters like HTMX and STEMNC were determined by the field measurements (Table 4).
Uncertain parameters in GECROS influencing crop carbon and N assimilation, organ formation, and soil water and N movement were set free and allowed to vary within the referenced ranges (Table 4). Moreover, there was a newly added parameter, rASSA, accounting for the uncertainty of estimated photosynthetic parameters. This was considered necessary because photosynthetic parameter values estimated in our previous study based on gas exchange and chlorophyll fluorescence measurements (Wang et al., 2022), had uncertainties. Firstly, the cultivars differed between our previous study and this study. Secondly, the data in our previous study was only limited to certain growing stages rather than in the whole growing season like this study. Thirdly, plant growth conditions differed, in greenhouse vs in field conditions, and photosynthetic parameters are known to acclimate to growth conditions (e.g., Cai et al. (2020); Yin et al. (2019)).
The remaining parameters in GECROS were set as default (Yin and van Laar, 2005).