26
Puddle model parameter reconciled with the lake model
(Klughammer and Schreiber 2008)
NPQ = Y(NPQ)/Y(NO) or NPQ= (Fm-Fm’)/Fm’ Klughammer and Schreiber reconcile NPQ
with the lake model using simplified parameters.
NPQ (resurrected puddle model parameter valid in Klughammer simplified Lake model
equations. See above.) is non-photochemical quenching and is a measure of heat dissipation.
NPQ is an alternate expression of non-photochemical quenching. It provides an estimate of
quenching without knowledge of Fo’ or Fod. The advantage of NPQ over qN depends on the
specific application. NPQ is more heavily affected by non-photochemical quenching that
reflects heat-dissipation of excitation energy in the antenna system. So, it may be thought of
as an indicator of 'excess excitation energy'. Alternatively, NPQ is relatively insensitive to the
part of nonphotochemical quenching associated with qN values lower than 0.6. The range of
NPQ is affected by )ph of the thylakoid lumen, and the xanthophyll cycle, state transitions
and photoinhibition. Numbers range from zero to infinity with typical samples measuring in
the 0.5 to 3.5 range (Maxwell and Johnson 2000). (Bilge & Bookman, 1990), (Muller P.,
Xiao-Ping L., Niyogi K. 2001).
Definitions - puddle model parameters
NPQ (puddle model parameter) is non-photochemical quenching and is a measure of heat
dissipation. NPQ is an alternate expression of non-photochemical quenching. It provides an
estimate of quenching without knowledge of Fo’ or Fod. The advantage of NPQ over q
N
depends on the specific application. NPQ is more heavily affected by non-photochemical
quenching that reflects heat-dissipation of excitation energy in the antenna system. So, it may
be thought of as an indicator of 'excess excitation energy'. Alternatively, NPQ is relatively
insensitive to the part of nonphotochemical quenching associated with q
N
values lower than
0.6. NPQ is affected by )ph of the thylakoid lumen, the xanthophyll cycle, state transitions
and photoinhibition. Numbers range from zero to infinity with typical samples measuring in
the 0.5 to 3.5 range (Maxwell and Johnson 2000). (Bilge & Bookman, 1990), (Muller P.,
Xiao-Ping L., Niyogi K. 2001).
q
N
(puddle model parameter) is similar to NPQ but requires Fod or Fo’ in the calculation.
qN is defined as the coefficient of non-photochemical fluorescence quenching. The original
definition of this term implied that fluorescence quenching affects primarily the 'variable
fluorescence' (Fv) and not the minimal fluorescence (Fo). In cases where qN is greater than
0.4 this may not be a good assumption. When q
N
is above 0.4, Fo’ (or Fod) should replace Fo
in q
P
equations. q
N
is less sensitive than NPQ at higher values (Maxwell and Johnson 2000).
By using the Far-Red source after actinic illumination is turned off, the PSII acceptors re-
oxidized and PSI is reduced. An Fo’ value is measured and used for corrections to the
quenching coefficients. Numbers range from zero to one. (puddle model) (Van Kooten &
Snell, 1990)
To Next Page
Loading...
