Mireille Consalvey PhD Thesis - University of St Andrews

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was associated with a sharp increase in PPFD. However, overall no relationship
was found between FIF,, 15 and PPFD (r = 0.290, df = 7, p=0.448).
Arlesford Creek: Changes in fluorescence parameters (Day 1)
The F0 15 yield significantly changed with time (178,81
= 2.62, p=0.013)
(Figure 5.7B). The only increase in minimum fluorescence yield together with a
positive rate of change in F, 15 was co-incident with the time of exposure at the
site. Using the Tukey's test it was detennined that there had been a significant
decrease in the fluorescence yield the start to the end of the sampling period.
There was no significant relationship between PPFD and F, 15. The rate of change
significantly varied with time (H = 17.66, df = 7, p=0.014) (Figure 5.7Q. With
the exception of between 105 and 255 min the mean rate of change was always
negative and the maximal rate of decrease occurred in the first 55 min.
The maximum light utilisation efficiency (FIF,, 15
) significantly varied
over the course of the day (F8,81 = 8.72, p