Photosynthetically active radiation ,

The photo synthetic aquatic biomass comprises cyanobacteria (formerly called blue-green algae), planktonic, filamentous and macrophytic algae, and vascular macrophytes. The net productivity of the floodwater depends on the level of primary production by the photosynthetic biomass versus its consumption by grazing animals, particularly cladocerans, copepods, ostracods, insect larvae and molluscs. Their role will change as the canopy develops and at a leaf area index of about 6-7 there will be no more photosynthetically active radiation available to them. 

FM = fresh mass DM = dry mass PAR = photosynthetically active radiation. 

Irradiation Measurements. An Epply photometer with sensors for total global irradiance, photosynthetic active radiation (PAR), and ultraviolet (UV) radiation (295-385 nm) was used to measure irradiance continuously and averaged a measurement every 0.5 h. 

Pa PACE PAGES PAHO PALE PAR PARCS PBL PCM PDV PhA PIK PIRA PIRATA POC POLDER Partial pressure in the atmosphere Permafrost And Climate in Europe Pilot Analysis of Global EcoSystems Pan American Health Organization Paleoclimates of Arctic Lakes and Estuaries Photosynthetic Active Radiation Paleoenvironmental ARCtic Science Planetary Boundary Layer Parallel Climate Model Pacific Decadal Variability Phytogenic Aerosol Potsdam-Institut fur Klimafolgenforschung Petroleum Industry Research Associates Pilot Research moored Array in the Tropical Atlantic Permanganate Oxidizable Carbon POLarization and Directionality of the Earth s Reflectances Princeton Ocean Model... 

High light intensity may have decreased the concentration of secondary metabolites if the plants were stressed by the high irradiance (see the environmental stress theory, Section IV.D). The plants grown at 100% of surface irradiance probably received high doses of ultraviolet radiation as well as photosynthetically active radiation. Ultraviolet radiation can stress Dictyota ciliolata, leading to decreased concentrations of secondary metabolites.183... 

Zangerl, A.R. and Berenbaum, M.R., Furanocoumarins in wild parsnip effects of photosynthetically active radiation, ultraviolet light, and nutrients, Ecology, 68, 516, 1987. 

Jokiel, P. L., Lesser, M. P., and Ondrusek, M. E., UV-absorbing compounds in the coral Pocillopora damicomis interactive effects of UV radiation, photosynthetically active radiation, and water flow, Limnol. Oceanogr., 42, 1468, 1997. 

Photosynthetically active radiation electromagnetic energy in the 400-700 nm wavelength range. 

Photosynthetic pigments compounds such chlorophylls, carotenoids, and phycobilins, used in absorbing photosynthetically active radiation (PAR). 

Artificially imposed short days enhance tuberization and, in many instances, significantly increase yield even though the length of exposure to photosynthetically active radiation is decreased (Hackbarth, 1937). 

FIGURE 10.7 Relationship between total dry matter biomass production and the cumulative intercepted photosynthetically active radiation for Columbia and Violet de Rennes at 51°58 N. (After Spitters, C.J.T. et al., in Topinambour (Jerusalem Artichoke), Report EUR 11855, Grassi, G. and Gosse, G., Eds., Commission of the European Communities, Luxembourg, 1988, pp. 37—43.)... 

All of the many biological transfer processes combine to determine a net surface resistance to transfer. Empirical relationships can be used to infer stomatal resistance from data on photosynthetically active radiation, water stress, temperature, atmospheric humidity and carbon dioxide levels. The resulting net surface resistance has been coupled with mathematical descriptions of aerodynamic and boundary-layer resistances in a "big leaf" model derived on the basis of agricultural and forest meteorology literature (4). At present, the big-leaf model is relatively coarse, permitting application only to areas dominated by maize, soybeans, grass, deciduous trees, and conifers. 

Interestingly, the levels of all the extractable flavonoids in the leaves of B. napus plants are decreased in a dose-dependent manner in response to UVA exposure. Additionally, the accumulation of the extractable flavonoids was examined by a shift from the photosynthetically active radiation (PAR) + UVA to PAR + UVB to assess whether the preexposure of the UVA affects the UVB-induced flavonoid accumulation. The UVA preexposures inhibited the UVB-induced accumulation of some flavonoids. This down regulation was particularly evident for quercetin-3-O-sophoroside and quercetin-3-O-sophoroside-7-O-glucoside of two anthocyanins. This is very interesting because the induction of quercetin by UVB is correlated with the UVB tolerance in some plant species. The photobiological nature of these UVA-mediated effects on flavonoid accumulation might suggest complex interactions between the UVA and UVB responses [66]. 

Regional Transport network, education and health services, regional organizations and markets Large-scale dieoffs of dominant species (e.g. bamboo), faunal distributions, alteration by smoke of Photosynthetically Active Radiation (PAR)... 

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