44. Estimating water status of wheat canopy using spectral reflectance in the 400-900 nm range

Water deficiency not only limits crop growth and nitrogen (N) uptake, but may also influence the accuracy of crop N status detection using optical sensors. Hence, knowing water status might be useful when optimizing split application rates. This study is focused on plant water detection. Field trials were conducted in Southeast Norway, with varied N-fertilization to induce variable canopy N status, and different water management (natural rainfall, rain-out shelters, drip irrigation) to induce various crop water status. Crop reflectance was measured at stem elongation and flag leaf emergence using a spectrophotometer, followed by the biomass-based water status estimation. The results indicate that multivariate methods are useful to extract information on canopy water status hidden behind more pronounced signals related to biomass density and nitrogen status.