|CENDRERO-MATEO, M.P. - Julich Research Center|
|PAPUGA, S.A. - University Of Arizona|
|ALONSO, L. - University Of Valencia|
|MORENO, J. - University Of Valencia|
|Ponce Campos, Guillermo|
|RASCHER, U. - Justus-Liebig University|
|WANG, G. - University Of Arizona|
Submitted to: Journal of Experimental Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/28/2015
Publication Date: 10/19/2015
Citation: Cendrero-Mateo, M., Moran, M.S., Papuga, S., Thorp, K.R., Alonso, L., Moreno, J., Ponce Campos, G.E., Rascher, U., Wang, G. 2015. Plant Chlorophyll fluorescence: active and passive measurements at canopy and leaf scales with different nitrogen treatments. Journal of Experimental Botany. 67(1):275-286.
Interpretive Summary: Crops produce a fluorescent light that is related to water and nutrient requirements. In the past, it has been necessary to apply light to the plant to measure the fluorescence response, termed the “active” approach. More recently, a new method has allowed crop producers to measure field-scale fluorescence with remote sensing (termed the “passive” approach). Although the measurement principles of both techniques are different, there is little information about the relation between crop studies using active and passive measurements. In this study, we investigated the potential for interchanging active and passive fluorescence measurements at different temporal and spatial scales. We concluded that active measurements can be used to better understand the daily and seasonal behavior of passive measurements from leaf to field scales. This finding can be used to better estimate plant photosynthetic capacity, and therefore, to provide improved information for crop management.
Technical Abstract: 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, although the measurement principles of both techniques are different, 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 uncertainty was largely related to leaf heterogeneity associated with variations in CO2 assimilation and stomatal conductance, and less so to leaf size or measurement inputs (e.g., solar radiation). 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 behavior 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.