Characterization of nitrogen and water status in oat leaves using optical sensing approach
Zhao, B., Ma, B.L., Hu, Y., Liu, J. (2015). Characterization of nitrogen and water status in oat leaves using optical sensing approach, 95(2), 367-378. http://dx.doi.org/10.1002/jsfa.6729
© 2014 Society of Chemical Industry. Background: Optical sensing is a potential tool to estimate plant N status, but soil water deficits may interefere with forming a clear relationship. A greenhouse study was conducted with oat plants treated with three water regimes and four N levels to determine whether optical sensing could be used to estimate leaf N and relative water content (RWC). Results: Leaf N was strongly correlated with reflectance at 550 nm and at around 705 nm, and N treatments caused a red-edge peak shift to lower wavelength. The ratio of the first derivative reflectance at 741-696 nm (FDRE) was identified to be a good estimator of leaf N at jointing (R2 = 0.90) and heading (R2 = 0.86) stages across water treatments. Leaf N also had a stronger association with the red-edge position (REP) at both stages (R2 = 0.83 and 0.78), or with the ratio R4 (R760/R550) at jointing (R2 = 0.88), than with chlorophyll meter (SPAD) readings. Under water stress, the predictive accuracy of leaf N increased with these reflectance indices, but decreased using SPAD readings. Conclusion: The results indicate that specific reflectance indices of FDRE, REP and R4 may be used for a rapid and non-destructive estimation of oat plant N status over a range of water regimes.
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