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Different Light Regimes (different + light_regime)
Selected AbstractsCASIROZ: Root Parameters and Types of Ectomycorrhiza of Young Beech Plants Exposed to Different Ozone and Light RegimesPLANT BIOLOGY, Issue 2 2007eleznik Abstract: Tropospheric ozone (O3) triggers physiological changes in leaves that affect carbon source strength leading to decreased carbon allocation below-ground, thus affecting roots and root symbionts. The effects of O3 depend on the maturity-related physiological state of the plant, therefore adult and young forest trees might react differently. To test the applicability of young beech plants for studying the effects of O3 on forest trees and forest stands, beech seedlings were planted in containers and exposed for two years in the Kranzberg forest FACOS experiment (Free-Air Canopy O3 Exposure System, http:www.casiroz.de) to enhanced ozone concentration regime (ambient [control] and double ambient concentration, not exceeding 150 ppb) under different light conditions (sun and shade). After two growing seasons the biomass of the above- and below-ground parts, beech roots (using WinRhizo programme), anatomical and molecular (ITS-RFLP and sequencing) identification of ectomycorrhizal types and nutrient concentrations were assessed. The mycorrhization of beech seedlings was very low (ca. 5 % in shade, 10 % in sun-grown plants), no trends were observed in mycorrhization (%) due to ozone treatment. The number of Cenococcum geophilum type of ectomycorrhiza, as an indicator of stress in the forest stands, was not significantly different under different ozone treatments. It was predominantly occurring in sun-exposed plants, while its majority share was replaced by Genea hispidula in shade-grown plants. Different light regimes significantly influenced all parameters except shoot/root ratio and number of ectomycorrhizal types. In the ozone fumigated plants the number of types, number of root tips per length of 1 to 2 mm root diameter, root length density per volume of soil and concentration of Mg were significantly lower than in control plants. Trends to a decrease were found in root, shoot, leaf, and total dry weights, total number of root tips, number of vital mycorrhizal root tips, fine root (mass) density, root tip density per surface, root area index, concentration of Zn, and Ca/Al ratio. Due to the general reduction in root growth indices and nutrient cycling in ozone-fumigated plants, alterations in soil carbon pools could be predicted. [source] Habitat use and foraging success of 0+ pike (Esox lucius L.) in experimental ponds related to prey fish, water transparency and light intensityECOLOGY OF FRESHWATER FISH, Issue 2 2002C. Skov Abstract ,,,This study investigated the habitat use of 0+ pike (9,17 cm) in relation to two different water transparency regimes (clear water/chlorophyll water), two different light regimes (day/night) and the presence/absence of prey using 16 m2 experimental ponds. Pike could freely choose between two structured habitats (a simple structured and a complex structured), an interface habitat (between the structured habitats and open water) and an open water habitat. Foraging success of the pike in relation to water transparency was investigated by comparing mean condition (Fultons K) of the pike as well as the number of surviving prey fish. Habitat use was influenced by the presence/absence of prey and varied between waters with different transparency. The presence of prey intensified the use of structural habitats of 0+ pike in both clear and chlorophyll waters. A preference for complex habitats was found in clear water and was presumably related to foraging. The pike in chlorophyll water, in contrast, appeared more evenly distributed among all habitats, as illustrated by a more intensive use of open water in chlorophyll water compared to the clear water. No detectable impact of water transparency on the foraging success of 0+ pike was found. [source] Sporulation of Plasmopara viticola: Differentiation and Light RegulationPLANT BIOLOGY, Issue 3 2002J. Rumbolz Abstract: The development of grape downy mildew (Plasmopara viticola) was followed histologically during the entire latent period until the appearance of mature sporangia. Production of sporangiophores and sporangia was assessed using low-temperature scanning electron (LTSEM) and fluorescent light microscopy. Time-course studies using attached leaves of Vitis vinifera cv. Müller-Thurgau revealed that the production of sporangiophores and sporangia is a highly coordinated process and is completed within 7 h. As this differentiation is assumed to occur only in darkness, the influence of light was investigated. For this purpose, different light regimes were applied to infected leaf discs of V. viniferacv. Müller-Thurgau. White light irradiation prevented formation of sporangia, although the growth of the mycelium was not affected. Many sporangiophores were observed that were abnormally shaped, i.e., short hyphae in clusters or thin, extremely elongated hyphae. For the formation of mature sporangia, a prolonged dark period was necessary. Light experiments suggest photosensitivity at the end of the latent period. A terminal white light irradiation caused an inhibitory effect, whereas a final phase of darkness promoted sporangium development. Different light qualities were tested, revealing an inhibition of sporangium development by blue light whereas neither red nor far-red light were effective. [source] An experimental assessment on the effects of photoperiod treatments on the somatic and gonadal growth of the juvenile European purple sea urchin Paracentrotus lividusAQUACULTURE RESEARCH, Issue 7 2010Eimear McCarron Abstract Determining the optimum light conditions for sea urchins reared in land-based systems is vital for the future use and assessment of possible commercial systems of sea urchin farming. The effects of two different light regimes, complete darkness and a long day photoperiod of 16 h light:8 h darkness, on the somatic and gonadal growth of the European sea urchin Paracentrotus lividus (19.5,23.0 mm) was investigated using the commercial UrchinPlatterÔ System over a 6-month period (5 March to 5 September). Hatchery-produced P. lividus were transported to the Aquaculture Fisheries Development Centre (AFDC, University College, Cork UCC). Before arrival at the AFDC, sea urchins were reared on a diet of Laminaria digitata. Females were the predominant species of the animal group, displaying a reproductive Stage III (growing stage) where gametogenesis was commencing. Results show that darkness supports higher somatic growth than the photoperiod treatment. Feeding rates were higher for sea urchins reared under darkness with gonadal growth increasing for both experimental treatments. Individuals reared under darkness had a higher per cent change in gonad index from the initial sample taken at the beginning of the experiment. [source] | ||||||||||