Exploring prediction mechanisms for temperature-induced variation in maximum carboxylation rate from spectral reflectance across 450-850 nm in cucumber leaves.

Abstract

Leaf spectral reflectance across 450-850 nm has been shown to predict maximum carboxylation rate (V _cmax), which varies with leaf temperature (T _leaf). However, the mechanism by which temperature-induced variation in V _cmax is predicted from reflectance remains unclear. The objective of this study was to explore this mechanism using spectral reflectance across 450-850 nm. We measured V _cmax across a range of T _leaf (18-31°C) and reflectance in cucumber (Cucumis sativus L.) leaves. Partial least squares regression models moderately predicted V _cmax (R² = 0.73), whereas T _leaf was weakly predicted (R² = 0.32). When only visible reflectance (450-700 nm) was used, prediction accuracy for both V _cmax and T _leaf declined (R² = 0.59 and 0.17). Because predicting T _leaf from reflectance suggests that temperature-related information may help predict temperature-induced variations in V _cmax, our results indicate that reflectance in 700-850 nm possibly captures temperature-induced variation in V _cmax.