Figure 1.
Changes in C. velia C, N, C∶N and carotenoids during a sinusoidal light∶dark cycle.
Changes in C (pg C cell−1, panel A), the ratio of C∶N (mol∶mol, panel B), N quotas(pg N cell−1, panel C) and the major carotenoids relative to chl a (presented as ratio per chl a, panel D) are shown. Error bars are calculated as standard deviations of n≥3 replicated. Average values (plus error bars) measured for LL (▪) and HL (□) grown C. velia are included for comparison. The dashed line shows the light intensity during the light part of the cycle, with a midday peak of 500 µmol photons m−2 s−1.
Table 1.
Abbreviations, equations and units.
Table 2.
Summary of cellular responses in C. velia grown under three different photon treatments.
Figure 2.
Room temperature and 77K fluorescence emission spectra for C. velia grown under LL and HL.
Spectra were normalized at the chlorophyll a fluorescence emission maxima. Given the fluorescence spectra was identical for HL and sinusoidal light∶dark cycle grown C. velia, we only show the results for the HL grown cells.
Figure 3.
Changes in C. velia major fluorescence parameters during a sinusoidal light∶dark cycle.
Changes in the Fv/Fm (panel A), ΦPSII (panel B), qP (panel C) and NPQ (panel D) are shown. Error bars are calculated as standard deviations of n≥3 replicated. Average values (plus error bars) measured for LL (▪) and HL (□) grown C. velia are included for comparison. The dashed line shows the light intensity during the light part of the cycle, with a midday peak of 500 µmol photons m−2 s−1.
Table 3.
Summary of physiological responses measured using fluorescence techniques in C. velia grown under three different photon treatments.
Figure 4.
Changes in C. velia light and dark reactions during a sinusoidal light∶dark cycle.
Changes in O2 evolution and ETRPSII (panel A), alpha (photosynthetic efficiency, panel B), C fixation rates (panel C) and the photosynthetic quotient (PQ, panel D) are shown. Error bars are calculated as standard deviations of n≥2 replicated. Average values (plus error bars) measured for LL (▪) and HL (□) grown C. velia are included for comparison. The dashed line shows the light intensity during the light part of the cycle, with a midday peak of 500 µmol photons m−2 s−1.
Table 4.
Summary of physiological responses measured by oxygen evolution and 14C fixation in C. velia grown under three different photon treatments.
Figure 5.
Respiratory and photosynthetic activities of C. velia.
Representative data of low (grown under HL conditions; grey line) and high (mid-morning maximum under sinusoidal light∶dark cycle; black line) photosynthetic rates are shown. Oxygen concentration was continuously monitored using Clark-type electrode in the dark (black banner) or in the light (white banner). For better comparison, curves were artificially shifted to the same initial value at the time 115 s. Data were normalized to chl a concentration of samples.