Because we are typically concerned with providing light to our aquariums primarily for the photosynthetic needs of the corals, the most appropriate measure is the quantum units, and, more specifically, we need to know the amount and quality of light available for photosynthesis.
As the sun begins its slow march to dusk, less energy penetrates the warm ocean and once again the coral’s zooxanthellae photosynthesize at a rate proportional to the amount of light falling upon them. At sunset, just as earlier in the day, they will again reach the Compensation Point and begin to extract oxygen from the water in order to survive. They will continue to do so until the next morning’s dawn and the process will begin anew.
The effect of irradiance and temperature on the photosynthesis …
The present model yields a photosynthesis–irradiance curve (PE-curve) in a hyperbola, which is described by three physiological parameters: effective cross-section ( σ PS II ), turnover time of electron transport chain ( τ ) and number of PSUs ( N ).
The Scientific World Journal - Hindawi Publishing Corporation
It is generally recognized that light intensity and light quality play an important role in plant growth, photosynthetic capacity, as well as various aspects of physiology (, ). Typically, optimal light irradiance is central to the productivity of plants, as excessive high or low light intensity often impacts photosynthesis, and then severely limit plant growth (). The present study demonstrated that biomass production of was much lower at light intensity levels of L1 (500 μmol m-2 s-1) and L2 (750 μmol m-2 s-1) than at L3 (1000 μmol m-2 s-1 - ), indicating that is a heliophyte. The observed growth response of to light intensity was similar to that of many tree species, such as species and which were reported to grown better under higher light irradiance (, ).
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The seedlings grown under blue light and red light treatments had significantly higher photosynthetic rate (Pn) and stomatal conductance (gs) values than other light quality treatments (A, B). In the 15 treatments, the highest Pn value was detected in treatments R3 (7.09 μmol m-2 s-1) and B3 (6.89 μmol m-2 s-1), whereas the lowest value was observed in treatment P1 (0.79 μmol m-2 s-1). Two-way ANOVA showed that both light quality and light intensity treatments, as well as the interaction between them significantly affected the Pn and gs of (). Meanwhile, there was a significant decrease in Pn and gs under all light qualities over the range of light intensities from 1000 μmol m-2 s-1 (L3) to 500 μmol m-2 s-1 (L1 - A, B).
Photosynthesis - an overview | ScienceDirect Topics
Data are reported as the mean ± standard deviation (SD), and all tests were performed using the SPSS® 16.0 statistical software package (SPSS, Chicago, IL, USA). A two-way ANOVA model with light quality and light intensity as the main fixed factors plus a light quality × light intensity interaction term, followed by Tukey’s multiple-range test, was performed for biomass accumulation, photosynthesis parameters, and leaf characteristics as well as the water-soluble polysaccharide yields. The data were tested for normality (Shapiro-Wilk normality test) before analysis of variance. All statistical analyses were performed at a 95 % confidence level.