© 2000 Heron Publishing—Victoria, Canada
Differentiation among effects of nitrogen fertilization treatments on conifer seedlings by foliar reflectance: a comparison
of methods
Jonathan A. Moran (1), Alan K. Mitchell (2), Graeme Goodmanson (2) and Keri A. Stockburger (2)
1. Department of Biology, University of Victoria, P.O. Box 3020, Stn CSC, Victoria, British Columbia V8W 3N5, Canada (jmoran@uvic.ca) / 2. Pacific Forestry Centre, Canadian Forest Service, 506 West Burnside Road, Victoria, British Columbia V8Z 1M5, Canada / Received January 12, 2000
Summary
Analysis of reflectance can be used to estimate foliar concentrations of photosynthetic pigments, thus providing information
on the physiological status of green plants. We compared several methods of reflectance analysis for the capacity to differentiate
among effects of fertilization treatments across different irradiances on seedlings of Engelmann spruce (Picea engelmannii Parry ex Engelm.). Seedlings were grown in two light treatments (0 and 60% shade) and three nitrogen (N) treatments (10, 25 and 100
mg N l–1) for one growing season, after which foliar reflectance of the needles was measured. Five indices were tested: R550 (% reflectance at 550 nm); red edge position; the ratio R698:R760; the structure independent pigment index (SIPI); and the photochemical reflectance index (PRI). Both the light and nutrient
treatments significantly affected foliar chlorophyll a and b and carotenoid concentrations.
Among the indices tested, R550, red edge position and R698:R760 ratio were related to chlorophyll concentration, and were significantly affected by both light and N treatments. Both SIPI
and PRI were related to chlorophyll and carotenoid concentrations.Among these relationships, PRI was affected by both treatments,
whereas SIPI was sensitive to N treatment but not to light treatment. All five indices were weakly but significantly correlated
with growth as measured by dry weight.
Keywords:
carotenoids, chlorophyll, Picea engelmannii, photochemical reflectance index, red edge, sensitivity analysis, structure independent pigment index.
