Modelling Grape Berry Growth and Quality as a Function of the Photothermal Product and Water Supply

ABSTRACT

Protected cultivation realizes efficient plant production via precise environmental control, with temperature, radiation and water being key factors affecting grape berry growth and quality. Thus, exploring their comprehensive impacts, constructing dynamic models and integrating these models with protected cultivation technologies can ensure efficient, stable grape production and enhanced berry quality. Based on four theoretical growth functions (Logistic, Gompertz, Richards and Weibull), we first established models for grape berry fresh weight (FW), water content (WC), total soluble solids (TSS) and titratable acid (TA) under 100% actual crop evapotranspiration (ETc), using photothermal products (PTP) and growing degree days (GDD) as driving variables. Water influence functions f(W) were then built as multipliers to modify these models, yielding 16 modified models for the four berry traits. Model calibration using 2021 data showed that GDD‐based models achieved higher simulation accuracy. However, during validation with 2022 data, PTP‐based models demonstrated better interannual stability and maintained reliable prediction performance, whereas GDD‐based models showed a substantial decline in accuracy. Among PTP‐based models, Mo‐L1 + L2 was optimal for FW, Mo‐O‐L for WC, Mo‐G1 + G2 for TSS and Mo‐L1‐L2 for TA. The simulation results indicated strong consistency with the measured data, confirming the models' high prediction accuracy.