Plant chlorophyll fluorescence: active and passive measurements at canopy and leaf scales with different nitrogen treatments.
Most studies assessing chlorophyll fluorescence (ChlF) have examined leaf responses to environmental stress conditions using active techniques. Alternatively, passive techniques are able to measure ChlF at both leaf and canopy scales. However, the measurement principles of both techniques are different, and only a few datasets concerning the relationships between them are reported in the literature. In this study, we investigated the potential for interchanging ChlF measurements using active techniques with passive measurements at different temporal and spatial scales. The ultimate objective was to determine the limits within which active and passive techniques are comparable. The results presented in this study showed that active and passive measurements were highly correlated over the growing season across nitrogen treatments at both canopy and leaf-average scale. At the single-leaf scale, the seasonal relation between techniques was weaker, but still significant. The variability within single-leaf measurements was largely related to leaf heterogeneity associated with variations in CO2 assimilation and stomatal conductance, and less so to variations in leaf chlorophyll content, leaf size or measurement inputs (e.g. light reflected and emitted by the leaf and illumination conditions and leaf spectrum). This uncertainty was exacerbated when single-leaf analysis was limited to a particular day rather than the entire season. We concluded that daily measurements of active and passive ChlF at the single-leaf scale are not comparable. However, canopy and leaf-average active measurements can be used to better understand the daily and seasonal behaviour of passive ChlF measurements. In turn, this can be used to better estimate plant photosynthetic capacity and therefore to provide improved information for crop management.
Soil Water and Environmental Science, The University of Arizona, 1177 East Fourth Street, Tucson 85721, USA USDA Southwest Watershed Research Center, 2000 East Allen Road, Tucson, AZ 85719, USA p.cendrero@fz-juelich.de.
M Pilar
MP
Cendrero-Mateo
USDA Southwest Watershed Research Center, 2000 East Allen Road, Tucson, AZ 85719, USA.
M Susan
MS
Moran
Soil Water and Environmental Science, The University of Arizona, 1177 East Fourth Street, Tucson 85721, USA School of Natural Resources, The University of Arizona, 325 Biosciences East, Tucson, AZ 85721, USA.
Shirley A
SA
Papuga
USDA Arid-Land Agricultural Research Center, 21881 North Cardon Lane, Maricopa, AZ 85138, USA.
K R
KR
Thorp
Image Processing Laboratory (IPL), Universitat de Valencia Catedratico A. Escardino - 46980 Paterna, Valencia, Spain.
L
L
Alonso
Image Processing Laboratory (IPL), Universitat de Valencia Catedratico A. Escardino - 46980 Paterna, Valencia, Spain.
J
J
Moreno
USDA Southwest Watershed Research Center, 2000 East Allen Road, Tucson, AZ 85719, USA.
G
G
Ponce-Campos
Institute of Bio- and Geosciences, Forschungszentrum Jülich GmbH, Leo-Brandt-Str., 52425 Jülich, Germany.
U
U
Rascher
Bridgestone Americas Agricultural Operations, 4140W. Harmon Rd., Eloy, AZ 85131, USA.
G
G
Wang
D002734:Chlorophyll / Q000737:chemistry*; D005453:Fluorescence; D009584:Nitrogen / Q000378:metabolism*; D018515:Plant Leaves / Q000737:chemistry; D014908:Triticum / Q000737:chemistry*
D002734:Chlorophyll; D009584:Nitrogen
FLD; Fluowat; PAM; chlorophyll content.; nitrogen