Mateja Germ | University of Ljubljana, Biotechnical Faculty (original) (raw)

Papers by Mateja Germ

Research paper thumbnail of Perspectives of Breeding Buckwheat for High Quality

The internationally coordinated research, performed in past and presence through international bi... more The internationally coordinated research, performed in past and presence through international bilateral projects, is briefly reported. The importance of nutritional quality of starch , proteins, phenolic substances and other constituents, and interactions among them, is discu ssed. Some possibilities of .further progress in breeding buckwheat for high nutritional quality of products are proposed.

Research paper thumbnail of Metabolic Importance of Selenium for Plants

Selenium (Se) is a trace element that is both an essential nutrient for humans and animals and an... more Selenium (Se) is a trace element that is both an essential nutrient for humans and animals and an environmental toxicant; the boundary between the two roles is narrow and depends on its chemical form, concentration, and other environmentally influenced variables. Se is important in the metabolism of cyanobacteria and some plants, being involved in their antioxidative processes. The essentiality of Se to higher plants, however, is still under debate. Although it is harmful for plants in high concentrations, it can exert beneficial effects at low concentrations. It can increase the tolerance of plants to UV-induced oxidative stress, delay senescence, and promote the growth of ageing seedlings. Recently it has been shown that Se is able to regulate the water status of plants under conditions of drought. It is widely distributed on the Earth's surface and available for plants in at least small traces. Cultivation of plants enriched with Se could be an effective way of producing Se-rich foodstuffs which can be beneficial to health. Se is also a major contaminant in the effluents from some oil refineries , power plants, and in mine drainage water. Se has become the primary element of concern in much environmental contamination because of its bioaccumulation in food webs. Bioaccumulation of Se is leading to toxic impact and changes in communities. However, it is possible to remove it from soils and Se-contaminated agricultural drainage water using plants in a phytoremediation process.

Research paper thumbnail of The Feasibility of Using Tartary Buckwheat as a Se-Containing Food Material

Journal of Chemistry, 2015

Tartary buckwheat (Fagopyrum tataricum) is a semiwild plant grown in the Himalaya region. Due to ... more Tartary buckwheat (Fagopyrum tataricum) is a semiwild plant grown in the Himalaya region. Due to its high concentration of flavonoids and trace elements it is of interest for cultivation in other countries as well. The feasibility of increasing the concentration of Se in grain and in green parts of Tartary buckwheat has not yet been investigated. The aim of this investigation was thus to determine the concentration of Se in different edible parts of Tartary buckwheat treated with different concentrations of Na selenate using different techniques. In plants grown in soil fertilized once with 0.5 and 10 mg Se L −1 , Se was efficiently translocated from the roots to the leaves and seeds. Foliar spraying with 0.5 mg Se L −1 increased Se content in leaves and seeds. Among the edible parts of Tartary buckwheat plants the highest content of Se in control and in treated groups was found in leaves, followed by seeds and stems. Regarding recommended Se concentration, edible parts of Tartary buckwheat were safe for human consumption. Soil fertilization with 0.5 and 10 mg Se L −1 and foliar fertilization with 0.5 mg Se L −1 are applicable for cultivation of Tartary buckwheat as a functional food enriched with Se.

Research paper thumbnail of Increased Temperature Due to Global Warming Alters the Respiratory Potential in Aquatic Organisms from an Oligotrophic Lake

International Review of Hydrobiology, 2010

The influence of elevated temperature was studied on the respiratory potential of a microplankton... more The influence of elevated temperature was studied on the respiratory potential of a microplankton community, two macrophytes species (Myriophyllum spicatum and Chara aspera), and sediments, all from an oligotrophic lake, in order to estimate their susceptibility to temperature change. Samples collected in winter, spring, summer and autumn were incubated at three different temperatures. The respiratory potential, measured as electron transport system (ETS) activity at a standard temperature of 20 °C was, in average, greater at higher incubation temperatures for 117% in microplankton and for 30% in sediments, indicating that elevated temperature influenced the respiratory capacity of the microbial communities for mineralization of organic matter through respiration. The large increases of respiratory potential in winter microplankton community (for 184% at the highest incubation temperature compared to the temperatures of the multiyear period) and spring microplankton community (190%), and in spring sediment (64%) reveal that those communities are most susceptible to elevated temperatures during the coldest period of a year and at the beginning of lake warming. The respiratory activity of Myriophyllum spicatum was independent of incubation temperature, indicating its wide physiological tolerance. The lower respiratory potential at higher temperatures in Chara aspera optimized the use of energy in plants.

Research paper thumbnail of Least Disturbed Condition for European Mediterranean rivers

Science of the Total Environment, 2014

Mediterranean Least Disturbed Streams (LDS) show various types of hydromorphological alterations.

Research paper thumbnail of The response of sunflower to acute disturbance in water availability

The influence of disturbance in water availability to electron flow in photosystem II was studied... more The influence of disturbance in water availability to electron flow in photosystem II was studied in five cultivars of sunflower. The results showed unaffected optimal quantum yield of photosystem II in the plants exposed to limited water supply, indicating the short-term tolerance of photosynthetic processes to acute water deficiency. Effective quantum yield of photosystem II was affected by interruption of

Research paper thumbnail of Rutin in buckwheat - Protection of plants and its importance for the production of functional food

The amount of ultraviolet (UV)-B absorbing compounds in buckwheat is related to UV-B radiation. T... more The amount of ultraviolet (UV)-B absorbing compounds in buckwheat is related to UV-B radiation. The increased terminal electron transport system (ETS) activity of mitochondria of plants, exposed to UV radiation , is suggested to reflect the energetic cost of generating the internal mechanisms for photoprotection. Rutin , quercetin, quercitrin and other flavonoids are secondary plant metabolites and are synthesized in

Research paper thumbnail of Best available conditions within common mediterranean stream types from 7 countries

The Mediterranean Rivers Geographic Intercalibration Group developed a 3-step approach that allow... more The Mediterranean Rivers Geographic Intercalibration Group developed a 3-step approach that allowed the characterization of the best available condition of four Mediterranean common stream types, regarding organic contamination and nutrients, hydrological and morphological alterations and land use. For this purpose, a common database composed of 7 member states national reference sites sampled for invertebrates, diatoms and macrophytes was used, with an initial number of 929 sample records gathered in different seasons, but mainly in spring. After a first step, the analyses of reference sites, classified with no-impact for hydromorphological changes, revealed that medium- size streams (100-1000 km 2) with highly seasonal hydrological regime are the most affected by extensive agriculture in the catchment, while non-siliceous rivers (e.g., calcareous river bed) are the most affected by intensive agriculture. Small rivers (<100 km 2) are those with a higher % of semi-natural areas. ...

Research paper thumbnail of Respiratory potential and Se compounds in pea (Pisum sativum L.) plants grown from Se-enriched seeds

Journal of Experimental Botany, 2006

Selenium (Se) has been proved to be an essential element for humans and animals. However, less is... more Selenium (Se) has been proved to be an essential element for humans and animals. However, less is known about its effects on plants. Pea plants were treated foliarly once (OT) and twice (TT) with Se solution during their flowering period. Seeds obtained from these plants contained 383 and 743 ng Se g21, respectively, and, together with control seeds from untreated

Research paper thumbnail of Bryophyte communities in hydrographic regions of Europe: distribution overview and conservation in global change scenarios

Research paper thumbnail of Metabolic Importance of Selenium for Plants

Selenium (Se) is a trace element that is both an essential nutrient for humans and animals and an... more Selenium (Se) is a trace element that is both an essential nutrient for humans and animals and an environmental toxicant; the boundary between the two roles is narrow and depends on its chemical form, concentration, and other environmentally influenced variables. Se is important in the metabolism of cyanobacteria and some plants, being involved in their antioxidative processes. The essentiality of

Research paper thumbnail of Flavonoid, tannin and hypericin concentrations in the leaves of St. John’s wort ( Hypericum perforatum L.) are affected by UV-B radiation levels

Food Chemistry, 2010

St. John’s wort (Hypericum perforatum L.) herb is used as a herb-tea or as a food supplement beca... more St. John’s wort (Hypericum perforatum L.) herb is used as a herb-tea or as a food supplement because of its antidepressive properties. St. John’s wort, grown under different levels of UV-B radiation, was analysed for its concentrations of flavonoids, tannins and hypericin. A high level of UV-B radiation increased leaf concentrations of flavonoids from 6.31 to 9.00/100g in dry matter

Research paper thumbnail of Selenium concentration in St. John’s wort ( Hypericum perforatum L.) herb after foliar spraying of young plants under different UV-B radiation levels

Food Chemistry, 2009

St. John’s wort (Hypericum perforatum L.) was grown under different levels of UV-B radiation, wit... more St. John’s wort (Hypericum perforatum L.) was grown under different levels of UV-B radiation, with selenium (10mgl−1 Se applied by foliar spraying in the form of sodium selenate) or without foliar Se application. The different levels of UV-B radiation comprised an enhanced level simulating 17% ozone depletion, ambient level, and a reduced level of UV-B radiation. The concentration of Se

Research paper thumbnail of The combined effects of elevated UV-B radiation and selenium on Tartary buckwheat (Fagopyrum tataricum) habitus

The possible ameliorative effect of selenium addition via the leaves on UV-B treated Tartary buck... more The possible ameliorative effect of selenium addition via the leaves on UV-B treated Tartary buckwheat plants (Fago­ pyrum tataricumi was monitored during a three month field experiment in the Botanical garden at Ljubljana (altitude 320 m above see level, 46°35'N , 14°55'E). The Tartary buckwheat was exposed to four treatments: ambient UV-B radi­ ation, ambient UV-B radiation with selenium (1

Research paper thumbnail of UV-B treated algae exhibiting different responses as a food source for Daphnia magna

Journal of Plankton Research, 2004

The response of green algae Scenedesmus quadricauda and Selenastrum capricornutum to different le... more The response of green algae Scenedesmus quadricauda and Selenastrum capricornutum to different levels of UV-B radiation was studied. Daphnia magna, the next step in the food web, was fed with UV-B treated algae. UV-B radiation induced the synthesis of UV absorbing substances and photosynthetic pigments, enhanced the level of respiratory potential and suppressed growth of the treated algae. Biomass production in S. quadricauda was higher than in S. capricornutum, but the production of photosynthetic pigments and relative amounts of UV absorbing substances as well as respiratory potential were more pronounced in S. capricornutum. A short-term feeding experiment with D. magna showed that in general, females ingested higher numbers of cells of algae treated with a high UV-B dose, but the biomass of ingested algae did not differ significantly. The exception was S. capricornutum treated with a high UV-B dose; a lower biomass was ingested, probably reflecting the smaller UV-treated cells.

Research paper thumbnail of Comparison of Aerial and Submerged Leaves in Two Amphibious Species, Myosotis scorpioides and Ranunculus trichophyllus

Photosynthetica, 2003

Both amphibious species, Myosotis scorpioides and Ranunculus trichophyllus, thrive in a stressful... more Both amphibious species, Myosotis scorpioides and Ranunculus trichophyllus, thrive in a stressful environment (alternated flooding and drying), which is variable regarding water and radiation regimes. Plants from the field and plants grown under controlled water table maintained at 40 cm were analysed for content of chlorophyll (Chl) and UV-B screening compounds, and the efficiencies of PS2 and electron transport systems.

Research paper thumbnail of The influence of enhanced UV-B radiation on Batrachium trichophyllum and Potamogeton alpinus — aquatic macrophytes with amphibious character

Journal of Photochemistry and Photobiology B-biology, 2002

The responses of two amphibious species, Batrachium trichophyllum and Potamogeton alpinus to diff... more The responses of two amphibious species, Batrachium trichophyllum and Potamogeton alpinus to different UV-B environments were studied. Plant material from natural environments, as well as from outdoor treatments was examined. In long-term outdoor experiments plants were grown under three different levels of UV-B radiation: reduced and ambient UV-B levels, and a UV-B level simulating 17% ozone depletion. The following parameters

Research paper thumbnail of The role of UV-B radiation in aquatic and terrestrial ecosystems—an experimental and functional analysis of the evolution of UV-absorbing

We analysed and compared the functioning of UV-B screening pigments in plants from marine, fresh ... more We analysed and compared the functioning of UV-B screening pigments in plants from marine, fresh water and terrestrial ecosystems, along the evolutionary line of cyanobacteria, unicellular algae, primitive multicellular algae, charophycean algae, lichens, mosses and higher plants, including amphibious macrophytes. Lichens were also included in the study. We were interested in the following key aspects: (a) does the water column

Research paper thumbnail of The role of UV-B radiation in aquatic and terrestrial ecosystems—an experimental and functional analysis of the evolution of UV-absorbing compounds

Journal of Photochemistry and Photobiology B-biology, 2002

We analysed and compared the functioning of UV-B screening pigments in plants from marine, fresh ... more We analysed and compared the functioning of UV-B screening pigments in plants from marine, fresh water and terrestrial ecosystems, along the evolutionary line of cyanobacteria, unicellular algae, primitive multicellular algae, charophycean algae, lichens, mosses and higher plants, including amphibious macrophytes. Lichens were also included in the study. We were interested in the following key aspects: (a) does the water column

Research paper thumbnail of Vpliv Vodotopnih Ogljikovih Hidratov V Zelju ( Brassica oleracea L. var. capitata ) Na Poškodbe, Ki Jih PovzroČa Tobakov Resar

Acta Agriculturae Slovenica, 2007

The impact of water-soluble carbohydrate composition in relation to damage levels of onion thrips... more The impact of water-soluble carbohydrate composition in relation to damage levels of onion thrips (Thrips tabaci Lindeman), were studied under field conditions at the Experimental Field of the Biotechnical Faculty in Ljubljana on 7 cabbage cultivar (Brassica oleracea L. var. capitata). Onion thrips showed weak preference on cabbage heads with high amount of total carbohydrate, fructose and glucose and higher preference on heads with high concentration of sucrose. While amount of total carbohydrate, fructose and glucose were negatively correlated with damage levels (r 2 = -0.7667; r 2 = -0.6947; r 2 = -0.8263), sucrose amount was not. There was a strong positively relationship between sucrose amount and the level of plants infested (r 2 = +0.7378). The cv.'Hinova', which had the highest amount of total carbohydrate, showed itself to be the most resistant to the onion thrips. IZVLEČEK VPLIV VODOTOPNIH OGLJIKOVIH HIDRATOV V ZELJU (Brassica oleracea L. var. capitata) NA POŠKODBE, KI JIH POVZROČA TOBAKOV RESAR Vpliv sestave vodotopnih ogljikovih hidratov na poškodbe, ki jih povzroča tobakov resar (Thrips tabaci Lindeman), smo proučevali na 7 kultivarjih zelja (Brassica oleracea L. var. capitata), vzgojenih na Laboratorijskem polju Biotehniške fakultete v Ljubljani. Tobakov resar je pokazal majhno preferenco do zeljnih glav, ki imajo visoko vsebnost skupnih ogljikovih hidratov, fruktoze in glukoze, in veliko preferenco do glav z visoko vsebnostjo saharoze. Medtem ko je vsebnost skupnih ogljikovih hidratov, fruktoze in glukoze negativno korelirala z indeksom poškodb (r 2 = -0,7667; r 2 = -0,6947; r 2 = -0,8263), pa to ni veljalo za saharozo. Med koncentracijo saharoze in poškodovanimi listi je bila namreč ugotovljena močno značilna Acta agriculturae Slovenica, 89 -1, avgust 2007 26 pozitivna povezava (r 2 = +0,7378). Cv. 'Hinova', ki je vseboval največji delež skupnih ogljikovih hidratov, se je pokazal kot najbolj odporen kultivar na napad tobakovega resarja.

Research paper thumbnail of Perspectives of Breeding Buckwheat for High Quality

The internationally coordinated research, performed in past and presence through international bi... more The internationally coordinated research, performed in past and presence through international bilateral projects, is briefly reported. The importance of nutritional quality of starch , proteins, phenolic substances and other constituents, and interactions among them, is discu ssed. Some possibilities of .further progress in breeding buckwheat for high nutritional quality of products are proposed.

Research paper thumbnail of Metabolic Importance of Selenium for Plants

Selenium (Se) is a trace element that is both an essential nutrient for humans and animals and an... more Selenium (Se) is a trace element that is both an essential nutrient for humans and animals and an environmental toxicant; the boundary between the two roles is narrow and depends on its chemical form, concentration, and other environmentally influenced variables. Se is important in the metabolism of cyanobacteria and some plants, being involved in their antioxidative processes. The essentiality of Se to higher plants, however, is still under debate. Although it is harmful for plants in high concentrations, it can exert beneficial effects at low concentrations. It can increase the tolerance of plants to UV-induced oxidative stress, delay senescence, and promote the growth of ageing seedlings. Recently it has been shown that Se is able to regulate the water status of plants under conditions of drought. It is widely distributed on the Earth's surface and available for plants in at least small traces. Cultivation of plants enriched with Se could be an effective way of producing Se-rich foodstuffs which can be beneficial to health. Se is also a major contaminant in the effluents from some oil refineries , power plants, and in mine drainage water. Se has become the primary element of concern in much environmental contamination because of its bioaccumulation in food webs. Bioaccumulation of Se is leading to toxic impact and changes in communities. However, it is possible to remove it from soils and Se-contaminated agricultural drainage water using plants in a phytoremediation process.

Research paper thumbnail of The Feasibility of Using Tartary Buckwheat as a Se-Containing Food Material

Journal of Chemistry, 2015

Tartary buckwheat (Fagopyrum tataricum) is a semiwild plant grown in the Himalaya region. Due to ... more Tartary buckwheat (Fagopyrum tataricum) is a semiwild plant grown in the Himalaya region. Due to its high concentration of flavonoids and trace elements it is of interest for cultivation in other countries as well. The feasibility of increasing the concentration of Se in grain and in green parts of Tartary buckwheat has not yet been investigated. The aim of this investigation was thus to determine the concentration of Se in different edible parts of Tartary buckwheat treated with different concentrations of Na selenate using different techniques. In plants grown in soil fertilized once with 0.5 and 10 mg Se L −1 , Se was efficiently translocated from the roots to the leaves and seeds. Foliar spraying with 0.5 mg Se L −1 increased Se content in leaves and seeds. Among the edible parts of Tartary buckwheat plants the highest content of Se in control and in treated groups was found in leaves, followed by seeds and stems. Regarding recommended Se concentration, edible parts of Tartary buckwheat were safe for human consumption. Soil fertilization with 0.5 and 10 mg Se L −1 and foliar fertilization with 0.5 mg Se L −1 are applicable for cultivation of Tartary buckwheat as a functional food enriched with Se.

Research paper thumbnail of Increased Temperature Due to Global Warming Alters the Respiratory Potential in Aquatic Organisms from an Oligotrophic Lake

International Review of Hydrobiology, 2010

The influence of elevated temperature was studied on the respiratory potential of a microplankton... more The influence of elevated temperature was studied on the respiratory potential of a microplankton community, two macrophytes species (Myriophyllum spicatum and Chara aspera), and sediments, all from an oligotrophic lake, in order to estimate their susceptibility to temperature change. Samples collected in winter, spring, summer and autumn were incubated at three different temperatures. The respiratory potential, measured as electron transport system (ETS) activity at a standard temperature of 20 °C was, in average, greater at higher incubation temperatures for 117% in microplankton and for 30% in sediments, indicating that elevated temperature influenced the respiratory capacity of the microbial communities for mineralization of organic matter through respiration. The large increases of respiratory potential in winter microplankton community (for 184% at the highest incubation temperature compared to the temperatures of the multiyear period) and spring microplankton community (190%), and in spring sediment (64%) reveal that those communities are most susceptible to elevated temperatures during the coldest period of a year and at the beginning of lake warming. The respiratory activity of Myriophyllum spicatum was independent of incubation temperature, indicating its wide physiological tolerance. The lower respiratory potential at higher temperatures in Chara aspera optimized the use of energy in plants.

Research paper thumbnail of Least Disturbed Condition for European Mediterranean rivers

Science of the Total Environment, 2014

Mediterranean Least Disturbed Streams (LDS) show various types of hydromorphological alterations.

Research paper thumbnail of The response of sunflower to acute disturbance in water availability

The influence of disturbance in water availability to electron flow in photosystem II was studied... more The influence of disturbance in water availability to electron flow in photosystem II was studied in five cultivars of sunflower. The results showed unaffected optimal quantum yield of photosystem II in the plants exposed to limited water supply, indicating the short-term tolerance of photosynthetic processes to acute water deficiency. Effective quantum yield of photosystem II was affected by interruption of

Research paper thumbnail of Rutin in buckwheat - Protection of plants and its importance for the production of functional food

The amount of ultraviolet (UV)-B absorbing compounds in buckwheat is related to UV-B radiation. T... more The amount of ultraviolet (UV)-B absorbing compounds in buckwheat is related to UV-B radiation. The increased terminal electron transport system (ETS) activity of mitochondria of plants, exposed to UV radiation , is suggested to reflect the energetic cost of generating the internal mechanisms for photoprotection. Rutin , quercetin, quercitrin and other flavonoids are secondary plant metabolites and are synthesized in

Research paper thumbnail of Best available conditions within common mediterranean stream types from 7 countries

The Mediterranean Rivers Geographic Intercalibration Group developed a 3-step approach that allow... more The Mediterranean Rivers Geographic Intercalibration Group developed a 3-step approach that allowed the characterization of the best available condition of four Mediterranean common stream types, regarding organic contamination and nutrients, hydrological and morphological alterations and land use. For this purpose, a common database composed of 7 member states national reference sites sampled for invertebrates, diatoms and macrophytes was used, with an initial number of 929 sample records gathered in different seasons, but mainly in spring. After a first step, the analyses of reference sites, classified with no-impact for hydromorphological changes, revealed that medium- size streams (100-1000 km 2) with highly seasonal hydrological regime are the most affected by extensive agriculture in the catchment, while non-siliceous rivers (e.g., calcareous river bed) are the most affected by intensive agriculture. Small rivers (<100 km 2) are those with a higher % of semi-natural areas. ...

Research paper thumbnail of Respiratory potential and Se compounds in pea (Pisum sativum L.) plants grown from Se-enriched seeds

Journal of Experimental Botany, 2006

Selenium (Se) has been proved to be an essential element for humans and animals. However, less is... more Selenium (Se) has been proved to be an essential element for humans and animals. However, less is known about its effects on plants. Pea plants were treated foliarly once (OT) and twice (TT) with Se solution during their flowering period. Seeds obtained from these plants contained 383 and 743 ng Se g21, respectively, and, together with control seeds from untreated

Research paper thumbnail of Bryophyte communities in hydrographic regions of Europe: distribution overview and conservation in global change scenarios

Research paper thumbnail of Metabolic Importance of Selenium for Plants

Selenium (Se) is a trace element that is both an essential nutrient for humans and animals and an... more Selenium (Se) is a trace element that is both an essential nutrient for humans and animals and an environmental toxicant; the boundary between the two roles is narrow and depends on its chemical form, concentration, and other environmentally influenced variables. Se is important in the metabolism of cyanobacteria and some plants, being involved in their antioxidative processes. The essentiality of

Research paper thumbnail of Flavonoid, tannin and hypericin concentrations in the leaves of St. John’s wort ( Hypericum perforatum L.) are affected by UV-B radiation levels

Food Chemistry, 2010

St. John’s wort (Hypericum perforatum L.) herb is used as a herb-tea or as a food supplement beca... more St. John’s wort (Hypericum perforatum L.) herb is used as a herb-tea or as a food supplement because of its antidepressive properties. St. John’s wort, grown under different levels of UV-B radiation, was analysed for its concentrations of flavonoids, tannins and hypericin. A high level of UV-B radiation increased leaf concentrations of flavonoids from 6.31 to 9.00/100g in dry matter

Research paper thumbnail of Selenium concentration in St. John’s wort ( Hypericum perforatum L.) herb after foliar spraying of young plants under different UV-B radiation levels

Food Chemistry, 2009

St. John’s wort (Hypericum perforatum L.) was grown under different levels of UV-B radiation, wit... more St. John’s wort (Hypericum perforatum L.) was grown under different levels of UV-B radiation, with selenium (10mgl−1 Se applied by foliar spraying in the form of sodium selenate) or without foliar Se application. The different levels of UV-B radiation comprised an enhanced level simulating 17% ozone depletion, ambient level, and a reduced level of UV-B radiation. The concentration of Se

Research paper thumbnail of The combined effects of elevated UV-B radiation and selenium on Tartary buckwheat (Fagopyrum tataricum) habitus

The possible ameliorative effect of selenium addition via the leaves on UV-B treated Tartary buck... more The possible ameliorative effect of selenium addition via the leaves on UV-B treated Tartary buckwheat plants (Fago­ pyrum tataricumi was monitored during a three month field experiment in the Botanical garden at Ljubljana (altitude 320 m above see level, 46°35'N , 14°55'E). The Tartary buckwheat was exposed to four treatments: ambient UV-B radi­ ation, ambient UV-B radiation with selenium (1

Research paper thumbnail of UV-B treated algae exhibiting different responses as a food source for Daphnia magna

Journal of Plankton Research, 2004

The response of green algae Scenedesmus quadricauda and Selenastrum capricornutum to different le... more The response of green algae Scenedesmus quadricauda and Selenastrum capricornutum to different levels of UV-B radiation was studied. Daphnia magna, the next step in the food web, was fed with UV-B treated algae. UV-B radiation induced the synthesis of UV absorbing substances and photosynthetic pigments, enhanced the level of respiratory potential and suppressed growth of the treated algae. Biomass production in S. quadricauda was higher than in S. capricornutum, but the production of photosynthetic pigments and relative amounts of UV absorbing substances as well as respiratory potential were more pronounced in S. capricornutum. A short-term feeding experiment with D. magna showed that in general, females ingested higher numbers of cells of algae treated with a high UV-B dose, but the biomass of ingested algae did not differ significantly. The exception was S. capricornutum treated with a high UV-B dose; a lower biomass was ingested, probably reflecting the smaller UV-treated cells.

Research paper thumbnail of Comparison of Aerial and Submerged Leaves in Two Amphibious Species, Myosotis scorpioides and Ranunculus trichophyllus

Photosynthetica, 2003

Both amphibious species, Myosotis scorpioides and Ranunculus trichophyllus, thrive in a stressful... more Both amphibious species, Myosotis scorpioides and Ranunculus trichophyllus, thrive in a stressful environment (alternated flooding and drying), which is variable regarding water and radiation regimes. Plants from the field and plants grown under controlled water table maintained at 40 cm were analysed for content of chlorophyll (Chl) and UV-B screening compounds, and the efficiencies of PS2 and electron transport systems.

Research paper thumbnail of The influence of enhanced UV-B radiation on Batrachium trichophyllum and Potamogeton alpinus — aquatic macrophytes with amphibious character

Journal of Photochemistry and Photobiology B-biology, 2002

The responses of two amphibious species, Batrachium trichophyllum and Potamogeton alpinus to diff... more The responses of two amphibious species, Batrachium trichophyllum and Potamogeton alpinus to different UV-B environments were studied. Plant material from natural environments, as well as from outdoor treatments was examined. In long-term outdoor experiments plants were grown under three different levels of UV-B radiation: reduced and ambient UV-B levels, and a UV-B level simulating 17% ozone depletion. The following parameters

Research paper thumbnail of The role of UV-B radiation in aquatic and terrestrial ecosystems—an experimental and functional analysis of the evolution of UV-absorbing

We analysed and compared the functioning of UV-B screening pigments in plants from marine, fresh ... more We analysed and compared the functioning of UV-B screening pigments in plants from marine, fresh water and terrestrial ecosystems, along the evolutionary line of cyanobacteria, unicellular algae, primitive multicellular algae, charophycean algae, lichens, mosses and higher plants, including amphibious macrophytes. Lichens were also included in the study. We were interested in the following key aspects: (a) does the water column

Research paper thumbnail of The role of UV-B radiation in aquatic and terrestrial ecosystems—an experimental and functional analysis of the evolution of UV-absorbing compounds

Journal of Photochemistry and Photobiology B-biology, 2002

We analysed and compared the functioning of UV-B screening pigments in plants from marine, fresh ... more We analysed and compared the functioning of UV-B screening pigments in plants from marine, fresh water and terrestrial ecosystems, along the evolutionary line of cyanobacteria, unicellular algae, primitive multicellular algae, charophycean algae, lichens, mosses and higher plants, including amphibious macrophytes. Lichens were also included in the study. We were interested in the following key aspects: (a) does the water column

Research paper thumbnail of Vpliv Vodotopnih Ogljikovih Hidratov V Zelju ( Brassica oleracea L. var. capitata ) Na Poškodbe, Ki Jih PovzroČa Tobakov Resar

Acta Agriculturae Slovenica, 2007

The impact of water-soluble carbohydrate composition in relation to damage levels of onion thrips... more The impact of water-soluble carbohydrate composition in relation to damage levels of onion thrips (Thrips tabaci Lindeman), were studied under field conditions at the Experimental Field of the Biotechnical Faculty in Ljubljana on 7 cabbage cultivar (Brassica oleracea L. var. capitata). Onion thrips showed weak preference on cabbage heads with high amount of total carbohydrate, fructose and glucose and higher preference on heads with high concentration of sucrose. While amount of total carbohydrate, fructose and glucose were negatively correlated with damage levels (r 2 = -0.7667; r 2 = -0.6947; r 2 = -0.8263), sucrose amount was not. There was a strong positively relationship between sucrose amount and the level of plants infested (r 2 = +0.7378). The cv.'Hinova', which had the highest amount of total carbohydrate, showed itself to be the most resistant to the onion thrips. IZVLEČEK VPLIV VODOTOPNIH OGLJIKOVIH HIDRATOV V ZELJU (Brassica oleracea L. var. capitata) NA POŠKODBE, KI JIH POVZROČA TOBAKOV RESAR Vpliv sestave vodotopnih ogljikovih hidratov na poškodbe, ki jih povzroča tobakov resar (Thrips tabaci Lindeman), smo proučevali na 7 kultivarjih zelja (Brassica oleracea L. var. capitata), vzgojenih na Laboratorijskem polju Biotehniške fakultete v Ljubljani. Tobakov resar je pokazal majhno preferenco do zeljnih glav, ki imajo visoko vsebnost skupnih ogljikovih hidratov, fruktoze in glukoze, in veliko preferenco do glav z visoko vsebnostjo saharoze. Medtem ko je vsebnost skupnih ogljikovih hidratov, fruktoze in glukoze negativno korelirala z indeksom poškodb (r 2 = -0,7667; r 2 = -0,6947; r 2 = -0,8263), pa to ni veljalo za saharozo. Med koncentracijo saharoze in poškodovanimi listi je bila namreč ugotovljena močno značilna Acta agriculturae Slovenica, 89 -1, avgust 2007 26 pozitivna povezava (r 2 = +0,7378). Cv. 'Hinova', ki je vseboval največji delež skupnih ogljikovih hidratov, se je pokazal kot najbolj odporen kultivar na napad tobakovega resarja.