9.D. Explanation of OJIP Parameters
The FluorPen also offers the possibility to capture rapid fluorescence transient – OJIP, which occurs during
exposure of plants to high irradiance. The FluorPen software enables data downloading to a personal
computer and subsequent OJIP analysis. The OJIP protocol includes the following extracted and technical
parameters*:
Formula Abbreviation Formula Explanation
Bckg Background
F
0
F
0
= F
50µs
, fluorescence intensity at 50 µs
F
J
F
J
= fluorescence intensity at J-step (at 2 ms)
F
i
F
i
= fluorescence intensity at i-step (at 60 ms)
F
M
F
M
= maximal fluorescence intensity
F
V
F
V
= F
M
- F
0
(maximal variable fluorescence)
V
J
V
J
= ( F
J
- F
0
) / ( F
M
- F
0
)
V
i
V
i
= ( F
i
- F
0
) / ( F
M
- F
0
)
F
M
/ F
0
F
V
/ F
0
Fv / F
M
M
0
or (dV/dt)
0
M
0
= TR
0
/ RC - ET
0
/ RC = 4 ( F
300
- F
0
) / ( F
M
- F
0
)
Area Area between fluorescence curve and F
M
(background subtracted)
Fix Area Area below the fluorescence curve between F
40µs
and F
1s
(background
subtracted)
S
M
S
M
= Area / ( F
M
- F
0
) (multiple turn-over)
S
S
S
S
= the smallest S
M
turn-over (single turn-over)
N N = S
M
. M
0
. ( 1 / V
J
) turn-over number Q
A
Phi_P
0
Phi_P
0
= 1 – ( F
0
/ F
M
)
(or F
V
/ F
M
)
Psi_
0
Psi_
0
= 1 - V
J
Phi_E
0
Phi_E
0
= ( 1 – ( F
0
/ F
M
)) . Psi_
0
Phi_D
0
Phi_D
0
= 1 – Phi_P
0
– ( F
0
/ F
M
)
Phi_Pav Phi_Pav = Phi_P
0
( S
M
/ t
FM
) t
FM
= time to reach F
M
(in ms)
ABS / RC ABS / RC = M
0
. ( 1 / V
J
) . (1 / Phi_P
0
)
TR
0
/ RC TR
0
/ RC = M
0
. ( 1 / V
J
)
ET
0
/ RC ET
0
/ RC = M
0
. ( 1 / V
J
) . Psi_
0
DI
0
/ RC DI
0
/ RC = ( ABS / RC ) – ( TR
0
/ RC )
* Formulas Derived From:
R.J. Strasser, A. Srivastava and M. Tsimilli-Michael (2000): The fluorescence transient as a tool to characterize
and screen photosynthetic samples. In: Probing Photosynthesis: Mechanism, Regulation and Adaptation (M.
Yunus, U. Pathre and P. Mohanty, eds.), Taylor and Francis, UK, Chapter 25, pp 445-483.
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