Abstract: The artificially controlled soil moisture experiments were performed in different growth periods on maize to measure the leaf stomatal conductance, leaf area index and canopy spectral reflectance. Then the changes in leaf stomatal conductance and the correlation relationships between the canopy spectral reflectance indices as well as leaf stomatal conductance were analyzed to construct leaf stomatal conductance models with considering the spectral vegetation index and soil moisture. The results indicated that the canopy reflectance of maize in visible and near medium and long infrared spectrum regions was increasing with the decreasing of soil moisture, while the stomatal conductance (Gs), leaf area index (LAI), ratio vegetation index (RVI) and normalized difference vegetation index (NDVI) were reducing. And the exponential functions and significantly positive correlations between NDVI/RVI and leaf/canopy stomatal conductance were also investigated. Furthermore, the spectral vegetation index better fitted into leaf stomatal conductance than into canopy stomatal conductance and the leaf stomatal conductance model with the consideration of RVI and soil moisture performed better than that with the consideration of NDVI and soil moisture. Thus the stomatal conductance in maize might be monitored real-timely, rapidly and quantitatively based on the canopy spectral reflectance and the work in this study could be fundamental to estimate crop stomatal conductance in large scales.

Key words: Maize, Leaf stomatal conductance, Canopy stomatal conductance, Canopy spectral reflectance, Normalized difference vegetation index, Ratio vegetation index