PhiNPQ, NPQ(T) and FvP/FmP

Measurements, Protocols & Macros

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Weizhen Liu

Feb 2018

MultispeQ v1.0 gives us both PhiNPQ and NPQ(T) values. Based on my reading of Tiet et al. 2017, PhiNPQ needs to be estimated after dark-adaptation but NPQ(T) does not. Using MultispeQ in the field with less than 1 minute measurement of each plant leaf, I think the leaf does not go through dark-adpation process before taking measurement. Can I say that NPQ(T) is more accurate than PhiNPQ when measuring by MultispeQ? When conducting analysis, can I throw away PhiNPQ in MultispeQ data set?

Additionally, MultispeQ also provides FvP/FmP parameter in the data sheet. What is the interpretation of FvP/FmP? Since Fv/Fm is maximal quantum efficiency of PSII, can I say FvP/FmP is steady-state quantum efficiency of PSII? If so, what is the difference between Phi2 and FvP/FmP? Thanks.

Answering the second part of the question...

FvP / FmP = (FmP - Fo) / FmP - efficiency of open reactions centers in the light. Phi2 = (FmP - Fs) / FmP = ΔF / FmP - quantum yield