Improved model inversion procedure for plant water status assessment under artificial lighting using PROSPECT+SAIL

Precision water management is desirable for value-added plant production in controlled environments. A procedure was developed to assess plant water status using a model-based hyperspectral approach. The PROSPECT+SAIL model was used to determine equivalent water thickness (EWT) from measured plant canopy reflectance (400 to 2500 nm) under artificial light sources. The major effort of this research was to improve the reliability of approximating best solutions of the non-linear model. To avoid inadequate local minima, boundaries of dependable variables were defined, and dimensionality of correlated dependent variable was reduced. The model performance was found disappointing in the spectral range between 400 and 1300 nm because of the spectral characteristics of the artificial light sources. However, the assessment of water status using the 1300 to 2500 nm spectral band was found promising. A reliable methodology was developed for accurate EWT determination of the New Guinea Impatiens in a growth chamber.