CHAPTER 12 MEASUREMENTS WITH THE MINI-PAM
displayed. Such reliable performance, which is not possible with
conventional amplifier systems, is of particular importance when
photosynthesis yield is low due to stress conditions. In such cases it
is essential to be sure that total inhibition really is indicated by
YIELD = 0.000. These aspects are illustrated in Fig. 12.
Note: A small lowering of fluorescence yield observed upon
application of a saturation pulse to the FLUORESCENCE
STANDARD is a genuine effect which results from a transient
temperature increase within the sample (see 12.3.4).
Fig. 12: Comparison of fluorescence responses of photosynthetically
active (Nerium; Lichen, +water) and inactive (Lichen, dry)
plant samples with those of a fluorescing plastic filter. ML,
measuring light; SP, saturation pulse. The calculated values
of effective quantum yield of energy conversion in PSII
(YIELD) are depicted.
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