Mireille Consalvey PhD Thesis - University of St Andrews

( iaptl 121 alory s l1o1iiflldtory hiafijin',
treated in some way to remove any PPFD effect (i. e. dark adaptation, supporting
the assumptions of all previous workers). This will be discussed in greater detail
below.
Hypothesis 3: Exposure to light will lead to a significant increase in the
minimum fluorescence yield and significant decreases in the maximum
fluorescence yield and light utilisation efficiency with the largest changes
occurring at the highest light level
Despite the fact that some increases were seen in the minimum
fluorescence yields of samples going from dark to light conditions, none of the
increases were significant. Theoretically an increase in the minimum
fluorescence yield should occur, but it is possible that the activation of NPQ
processes may mask any increase. It is further possible that the statistical test was
not powerful enough. The problems associated with the statistical analysis of
fluorescence data will be discussed in greater detail below. The F,, ' yield
significantly decreased when exposed to high light (low temperature only),
suggesting that NPQ processes had been activated. Associated with this decline
was a decrease in the light utilisation efficiency (FqIF, '). Therefore hypothesis 3
was accepted for light exposure leading to decreases in the maximum
fluorescence yield and light utilisation efficiency.
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