Spectral Reflectance and Physiological Measurement of Cassava under Water Stress Environment

Abstract

Plant water stress is the impact factor in the development of storage root stage of cassava and directly effects to the cassava yield. The application of remote sensing technology can be determined the plant water stress for rapid method and non-destructive plant. The objective of this study was detected the feasibility of the cassava water stress measurement using spectral reflectance under field scale. The field experiment was conducted in Khonkaen province, in a dry season period, October and November 2015, cassava Rayong 9, under irrigation and rainfed. Spectral reflectance and physiology measurement were collected at 3 to 5 months after planting and divided to 2 datasets for calibration and validation dataset. Then, the data correlation analysis was analyzed for the calibration model, including regression equation and the coefficient of determination (R²). Moreover, validation was determined the accuracy between measured and estimated value. The result showed the reflectance at wavelength 680 nanometer and SAVI were related to the average of photosynthesis and stomatal conductance (R² > 0.70). The validation was determined, less data discrepancy and r-square valued greater than 0.80. Therefore, the reflectance at wavelength 680 nanometer and SAVI could be detected the cassava water stress, using the average of photosynthesis and stomatal conductance. This research was preliminary studied for the advanced study to conduct in several field condition using unmanned aerial vehicle and/or spaceborne hyperspectral sensors for the existing water management to be more efficient.