Norbert Keutgen - Academia.edu (original) (raw)
Papers by Norbert Keutgen
Sugar Industry-Zuckerindustrie, 2010
Geologie En Mijnbouw, Nov 1, 2011
During the last decades, belemnitellid cephalopods (Coleoidea) have been considered to be of fund... more During the last decades, belemnitellid cephalopods (Coleoidea) have been considered to be of fundamental importance for biostratigraphy and correlation of the Upper Cretaceous of Europe, particularly during the Santonian to Maastrichtian stages, because they are common and widely distributed and have a high fossilisation potential (Christensen, 1996, 1997). However, detailed studies carried out by Christensen (1995, 1999, 2000a, b) have shown a significant regional component within distributional patterns, in particular for the genus Belemnitella, during the late Campanian in northwest Europe. While in Norfolk (southeast England), the Maastricht-Aachen-Liège area (MAL; southeast Netherlands and adjacent areas) and the Mons Basin (southern Belgium), members of the lineage Blt. mucronata / woodi / minor I/ minor II predominate, Blt. mucronata persisted in northern Germany (Misburg-Höver area, east of Hannover) and Skåne, southern Sweden, (almost) to the top of the Blt. woodi Zone in the lower upper Campanian. In the upper upper Campanian, members of the Blt. minor group have not (yet) been identified in northern Germany (Kronsmoor, Lägerdorf), but there Blt. langei (sensu Schulz, 1978) and Blt. schulzi appear, two forms apparently restricted to that region and unknown from Norfolk, the Mons Basin and the MAL area. From the Vistula (Wisła) River valley in east-central Poland, another rich Belemnitella fauna has recently been noted in the upper Campanian, comprising additional regional elements such as Blt. posterior Kongiel, 1962 (Christensen, unpubl. data; Remin, 2007). According to Christensen (2000b), his earlier suggestion (see Christensen, 1999) that the upper Campanian belemnite zonation of Norfolk could be used as a formal zonation throughout northwest Europe was no longer tenable. Hence, it is necessary first to establish regional belemnite zonations based on developmental lineages of the locally dominant species and, secondly, to note temporary invasions of additional species. These short-term invasions may be of great stratigraphic value as has been documented for instance for Bln. praearkhangelskii in the upper lower Maastrichtian of northwest Europe (Schulz, 1979; Keutgen, 1997). Alternatively, such temporary immigration events may reflect temporarily suitable environmental
Acta horticulturae, Jul 1, 2023
Erwerbsobstbau, Jul 7, 1997
Journal of Agronomy and Crop Science, Dec 1, 1995
Accumulation of assimilates in stem‐rust‐infected wheat leaves Using wheat plants (cv. ‘Prelude’)... more Accumulation of assimilates in stem‐rust‐infected wheat leaves Using wheat plants (cv. ‘Prelude’), the effects of stem‐rust infection on photosynthesis and assimilate partitioning were studied with the aid of the short‐lived carbon isotope 11C. Photosynthesis of strongly infected leaf parts declined by about 30 % within 1 day. This rapid inhibition was caused by the formation of appressoria and the growth of infection tubes into the stomata, leading to a reduction in gas exchange. Further decline of photosynthesis to 5–10 % was accompanied by the degradation of chlorophyll. Nevertheless, during sporulation, the dry weight of the infected leaf area increased by about 50 %. With the use of 11C, the reduced export of photosynthate from the infected leaf part and the capture of labelled compounds from the apical leaf section were quantified. The enhanced storage of assimilates in stem‐rust‐infected leaves can be attributed to the increase in invertase activity.
Strawberry plants of cvs 'Elsanta' and 'Korona' were grown during three months for eight hours fi... more Strawberry plants of cvs 'Elsanta' and 'Korona' were grown during three months for eight hours five days a week in an atmosphere that contained 65 ppb ozone. Analyses of soluble phenols in leaves indicated that ozone reduced total soluble phenol content, especially contents of agrimoniin, pedunculagin, and GE-56 in both cultivars. The effect of ozone fumigation differed from changes in soluble phenol content related to leaf ageing. The latter process resulted not only in a reduction of almost all soluble phenols but also in an increasing percentage of the flavonoid components. The reduction of gallic acid derivatives and ellagitannins in ozone-treated leaves may be explained by a shortage of their precursor substances phosphoenolpyruvate and erythrose-4-phosphate or by a consumption of soluble phenols in response to ozone stress. Zusammenfassung Erdbeerpflanzen der Sorten 'Elsanta' und 'Korona' wurden drei Monate lang fünf Tage pro Woche in einer Atmosphäre von 65 ppb Ozon angezogen. Analysen der löslichen Phenole ergaben, dass Ozon die Konzentration aller löslichen Phenole absenkte, jedoch besonders die von Agrimoniin, Pedunculagin und GE-56 in beiden Sorten. Die Auswirkungen der Ozonbegasung auf die Phenolgehalte unterschieden sich von Blattalterungsprozessen. Letztere bewirkten nicht nur eine Konzentrationsabsenkung sämtlicher löslichen Phenole sondern auch einen steigenden Prozentanteil an Flavonoiden. Die Konzentrationsabnahme der Gallussäurederivate und Ellagitannine in mit Ozon gestressten Blättern kann sowohl auf eine Unterversorgung mit den Vorläufersubstanzen Phosphoenolpyruvat und Erythrose-4-Phosphat zurückgeführt werden als auch mit einem Verbrauch löslicher Phenole in Folge eines Ozonstresses erklärt werden.
Acta horticulturae, May 1, 2003
In a two-year study, strawberry (Fragaria X ananassa Duch.) cvs 'Elsanta' and 'Korona' showed dif... more In a two-year study, strawberry (Fragaria X ananassa Duch.) cvs 'Elsanta' and 'Korona' showed differences in their sensitivities to salinity as applied by irrigating plants with nutrient solutions with 30 mM or 60 mM NaCl concentration. One month after start of treatments, necrotic symptoms appeared on leaf margins of 'Elsanta'. 'Korona' leaves, however, showed any to few symptoms. During the first growing season, salinity impaired the growth of 'Elsanta' leaves as indicated by a reduction in leaf area, leaf expansion rate and dry weight. During the second season, the reduction in leaf growth was more severe. By comparison, growth of 'Korona' leaves was reduced only during the second season. Total leaf number was unaffected by salinity in both cultivars; however, the number of dead leaves increased significantly due to salinity in 'Elsanta', but remained fairly unchanged in 'Korona'. Maximum assimilation rates and carboxylation efficiencies, calculated from the A/C i curves of leaves, were reduced by 39% and 44% in 'Elsanta' and by 22% and 34% in 'Korona', respectively. The net photosynthetic rate of 'Elsanta' was slightly reduced in tendency by salt treatments, while in 'Korona' the reduction was significant at the highest salt treatment. Salinity had no effect on the Na + content in leaves of both cultivars. However, the leaf Clcontent increased with increasing salt level, reaching maximum value in 'Elsanta' leaves treated with the highest salt level. This indicates that the effect of salt on leaves was due to Cl-, not to Na +. Root Na + content increased with salinity in both cultivars. The increase in root Clcontent in 'Elsanta' was not significant, but it rose in tendency. Clcontent in 'Korona' roots increased significantly with increasing salt level. This suggest that 'Korona' strawberry is able to accumulate absorbed Clin root tissues, thus preventing the translocation of this toxic ion to the leaves.
Journal of Plant Physiology, 1997
Gas exchange, chlorophyll fluorescence parameters, and macronutrient contents were investigated i... more Gas exchange, chlorophyll fluorescence parameters, and macronutrient contents were investigated in young «3weeks), medium (4-6weeks) and old (7-9weeks) strawberry leaves growing at 300, 450, 600, 750, and 900 ppm CO 2 • An increase of the CO 2 level to 600 ppm promoted leaf net photosynthesis, but a further rise led to a decrease of net CO 2 assimilation. The reduction of net photosynthetic rate was less distinct in young leaves exposed to CO 2 levels above 600 ppm for less than 3 weeks, indicating that the reduction might depend on the period of exposition or leaf age. Transpiration and stomatal conductance were significantly affected by leaf age, but not by CO 2 concentrations. Medium leaves were characterised by a higher transpiration rate and stomatal conductance than young and old ones. In leaves growing at high CO 2 levels ChI a and b contents as well as the alb ratio decreased. The contents ofN, P, K, Ca and Mg were lower in leaves growing at high CO 2 concentrations than in those at low ones. An elevated CO 2 level above 750 ppm led to a general macronutrient deficiency and was accompanied by a distinct decrease of optimal quantum yield, due to a rise of basal fluorescence, and an increase of non-photochemical energy dissipation in old leaves.
日本植物生理学会年会およびシンポジウム 講演要旨集 第45回日本植物生理学会年会講演要旨集, Mar 27, 2004
Agriculture, Sep 19, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Neues Jahrbuch für Geologie und Paläontologie, Feb 26, 2021
Photosynthetica, May 28, 2020
Evidence that the green fluorescence protein (GFP) develops a significant toxicity in plants has ... more Evidence that the green fluorescence protein (GFP) develops a significant toxicity in plants has not been found, but it may represent a source of free radicals as a consequence of its fluorescence. In addition, green light is known to trigger the acclimatisation of the photosynthetic system towards a shady environment. Moreover, the light-harvesting system may acclimate to an increased availability of green light. Each of these effects may be induced by the GFP. Therefore, the hypothesis was tested, whether transformation of Nicotiana tabacum cv. Bursan to express the GFP could affect chlorophyll fluorescence parameters. The analysis revealed a significantly lower absorption of energy per excited cross section in GFP-transformed tobacco, a lower number of active reaction centres per excited cross section, a larger absorption and trapped energy flux leading to the reduction of the primary quinone electron acceptor of PSII per reaction centre, and a lower variable fluorescence.
The South African Journal of Plant and Soil, 1998
Soil respiration is a major contributor to the carbon flux in apple orchards, but very little dat... more Soil respiration is a major contributor to the carbon flux in apple orchards, but very little data exist for citrus. Daytime soil respiration, grass respiration, and grass photosynthesis were recorded in a 'Nules' clementine (Citrus reticulata Blanco) orchard on 'Carrizo' citrange or 'X639' rootstock in Stellenbosch, Republic of South Africa, under typically variable spring weather conditions such as cool to hot, and clear to cloudy days. The amount of CO 2 contributed by the citrus roots and the Oakleaf soil type to the carbon fluxes in the orchard, was evaluated. Soil respiration rate in the citrus rows varied between 0.1 and 0.4 g CO 2 m-2 h-1 and increased with temperature, with a Q10 of about 1.4. After rainfall or irrigation, soil respiration was higher, especially at elevated temperatures. The rootstocks 'Carrizo' and 'X639' were characterised by slightly different rates of soil respiration. The difference was more pronounced after irrigation, and soil respiration of 'X639' exceeded that of 'Carrizo' by 0.03 to 0.04 g CO 2 m-2 h-1. Grass respiration between the rows ranged from 0.7 to 1.4 g CO 2 m-2 h-1 and grass net photosynthesis exceeded 1.0 g CO 2 m-2 h-1 , indicating that the grass strips between the tree rows act as a sink for CO 2 during the light period. It was concluded that soil respiration represents a major source of CO 2 in a citrus orchard.
Herba Polonica, Dec 1, 2015
Introduction: Allium ursinum L. has a commercial value due to its high contents of bioactive comp... more Introduction: Allium ursinum L. has a commercial value due to its high contents of bioactive compounds and mild, garlic-like taste. In vitro culture played an important role in obtaining Allium species with the desired characteristics and in the production of healthy reproductive material. Objective: Developing an effective method of sterilization bear's garlic bulbs. Methods: To obtain sterile shoots of garlic several methods of sterilization involving such factors as ACE, H 2 O 2 , HgCl 2 , and UV-C were tested. Results: In order to obtain sterile shoots of bear's garlic, several sterilization procedures were tested. The best procedure was based on a two-step disinfection, where the whole onions were treated with ethanol and H 2 O 2 for 20 min. Thereafter, the isolated apical buds were sterilized in ACE for 10 min, rinsed in double-distilled water and transferred onto MS medium for growing. Up to 95% of the inoculated explants formed shoots, which were sub-cultured on MS with 4 mg dm-3 BAP in order to enable further propagation. Conclusion: After optimization and stabilization, this procedure may become the basic concept of a proper and reliable propagation method of bear's garlic on commercial scale.
Acta horticulturae, May 1, 2003
The present investigation was aimed at assessing the response of 'Elsanta' and 'Korona' strawberr... more The present investigation was aimed at assessing the response of 'Elsanta' and 'Korona' strawberry plants to three levels (0, 40 and 80 meq/L) of NaCl-salinity stress and to describe salt effects on fruit quality. The investigated cultivars differed in their sensitivity to NaCl salinity. Typical stress symptoms such as leaf necroses, growth retardation and a poor fruit yield were observed in both cultivars, but 'Elsanta' was more sensitive than 'Korona'. In both cultivars, salt stress lowered the concentration of titratable acids in the fruit. In 'Elsanta', the content of soluble solids was reduced, while that of proteins increased. Vitamin C and E contents of fruits remained fairly stable as did relative dry matter in both cultivars.
Scientia Horticulturae, 2002
A/C i and photosynthetic light response curves for gas exchange characteristics were measured for... more A/C i and photosynthetic light response curves for gas exchange characteristics were measured for spur leaves of 25-year-old 'Golden Delicious' and 'Granny Smith' apple trees (Malus domestica Borkh.) to investigate their acclimation capacity to a shade-to-sun transition in a commercial apple orchard. Spur leaves of both cultivars adapted to summer-pruning within 2 weeks, regardless of the time of the season at which pruning was conducted. There were no significant differences between the spur leaves of later pruned trees and corresponding leaves on trees that were continuously pruned during the summer period in terms of net photosynthetic rate and carboxylation efficiency, for both cultivars. The shape of the photosynthetic light response curves also proved the acclimation potential of both cultivars to shade-to-sun transitions. The rapid increase of the chlorophyll a/b ratio after pruning indicated that the acclimation of the photosynthetic system to avoid over-excitation of the photosynthetic reaction centers occurred within 1 week. Nevertheless, leaf dry mass per leaf area was intermediate between 'continuous summer-pruning' and 'no-pruning' treatments for leaves on later pruned trees, indicating that the acclimation to shade-to-sun transitions was not perfect in either cultivar. The present data also Scientia Horticulturae 92 (2002) 9-27 Abbreviations: A, net photosynthetic rate; A max , maximum photosynthetic rate; C i , intercellular CO 2 concentration; Chl, chlorophyll; g 0 m , carboxylation efficiency; g s , stomatal conductance; l, stomatal limitation; PPFD, photosynthetic photon flux density
Scientific Reports
Perennial ryegrass is a grass species used to establish lawns in urban areas where pollution is a... more Perennial ryegrass is a grass species used to establish lawns in urban areas where pollution is a major environmental problems. Cadmium (Cd) and nickel (Ni) contribute significantly to these pollutants and may cause photosynthetic limitation. The main objective of this work was to perform a comprehensive analysis of photosynthetic efficiency of perennial ryegrass seedlings under Cd and Ni stress. Some of the main indices of photosynthetic efficiency (prompt and delayed chlorophyll-a fluorescence signals and modulated reflectance at 820 nm) were compared with growth parameters. Two cultivars were tested: 'Niga' and 'Nira'. A decrease in photosystem (PS) II and PSI activity was observed. This was due to an increase in nonradiative dissipation of the PSII antenna, a decrease in PSII antenna size, or a decrease in the number of photosynthetic complexes with fully closed PSII RCs. Efficiency of electron transport was decreased. The effect on the modulated reflectance sign...
Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen
Two-week-old strawberry (Fragaria x ananassa Duch. cv. 'Elsanta') plants were acc... more Two-week-old strawberry (Fragaria x ananassa Duch. cv. 'Elsanta') plants were acclimatized to 300, 450, 600, 750 or 900 ppm CO2 in controlled environment chambers for 50 days. An elevated CO2 concentration enhanced up to 750 ppm total chlorophyll a and chlorophyll b contents as well as the a/b ratio. Long-term CO2 enrichment induced leaf senescence and decreased photosynthetic efficiency as well as photochemical conversion efficiency of PS II. Intercellular CO2 concentration significantly increased with CO2 enrichment. Stomatal conductance, transpiration rate, and net photosynthesis rate of young leaves increased with raising CO2 concentrations. However, CO2 levels above 600 ppm markedly reduced net photosynthetic rate of adult and old leaves. High CO2 concentrations up to 900 ppm did not significantly affect dark respiration rate of the leaves. Photosynthetic water-use efficiency was highest in old leaves and lowest in young one. Increased CO2 concentrations up to 600-750 ppm improved leaf photosynthetic capacity by increasing photosynthetic water-use efficiency.
Sugar Industry-Zuckerindustrie, 2010
Geologie En Mijnbouw, Nov 1, 2011
During the last decades, belemnitellid cephalopods (Coleoidea) have been considered to be of fund... more During the last decades, belemnitellid cephalopods (Coleoidea) have been considered to be of fundamental importance for biostratigraphy and correlation of the Upper Cretaceous of Europe, particularly during the Santonian to Maastrichtian stages, because they are common and widely distributed and have a high fossilisation potential (Christensen, 1996, 1997). However, detailed studies carried out by Christensen (1995, 1999, 2000a, b) have shown a significant regional component within distributional patterns, in particular for the genus Belemnitella, during the late Campanian in northwest Europe. While in Norfolk (southeast England), the Maastricht-Aachen-Liège area (MAL; southeast Netherlands and adjacent areas) and the Mons Basin (southern Belgium), members of the lineage Blt. mucronata / woodi / minor I/ minor II predominate, Blt. mucronata persisted in northern Germany (Misburg-Höver area, east of Hannover) and Skåne, southern Sweden, (almost) to the top of the Blt. woodi Zone in the lower upper Campanian. In the upper upper Campanian, members of the Blt. minor group have not (yet) been identified in northern Germany (Kronsmoor, Lägerdorf), but there Blt. langei (sensu Schulz, 1978) and Blt. schulzi appear, two forms apparently restricted to that region and unknown from Norfolk, the Mons Basin and the MAL area. From the Vistula (Wisła) River valley in east-central Poland, another rich Belemnitella fauna has recently been noted in the upper Campanian, comprising additional regional elements such as Blt. posterior Kongiel, 1962 (Christensen, unpubl. data; Remin, 2007). According to Christensen (2000b), his earlier suggestion (see Christensen, 1999) that the upper Campanian belemnite zonation of Norfolk could be used as a formal zonation throughout northwest Europe was no longer tenable. Hence, it is necessary first to establish regional belemnite zonations based on developmental lineages of the locally dominant species and, secondly, to note temporary invasions of additional species. These short-term invasions may be of great stratigraphic value as has been documented for instance for Bln. praearkhangelskii in the upper lower Maastrichtian of northwest Europe (Schulz, 1979; Keutgen, 1997). Alternatively, such temporary immigration events may reflect temporarily suitable environmental
Acta horticulturae, Jul 1, 2023
Erwerbsobstbau, Jul 7, 1997
Journal of Agronomy and Crop Science, Dec 1, 1995
Accumulation of assimilates in stem‐rust‐infected wheat leaves Using wheat plants (cv. ‘Prelude’)... more Accumulation of assimilates in stem‐rust‐infected wheat leaves Using wheat plants (cv. ‘Prelude’), the effects of stem‐rust infection on photosynthesis and assimilate partitioning were studied with the aid of the short‐lived carbon isotope 11C. Photosynthesis of strongly infected leaf parts declined by about 30 % within 1 day. This rapid inhibition was caused by the formation of appressoria and the growth of infection tubes into the stomata, leading to a reduction in gas exchange. Further decline of photosynthesis to 5–10 % was accompanied by the degradation of chlorophyll. Nevertheless, during sporulation, the dry weight of the infected leaf area increased by about 50 %. With the use of 11C, the reduced export of photosynthate from the infected leaf part and the capture of labelled compounds from the apical leaf section were quantified. The enhanced storage of assimilates in stem‐rust‐infected leaves can be attributed to the increase in invertase activity.
Strawberry plants of cvs 'Elsanta' and 'Korona' were grown during three months for eight hours fi... more Strawberry plants of cvs 'Elsanta' and 'Korona' were grown during three months for eight hours five days a week in an atmosphere that contained 65 ppb ozone. Analyses of soluble phenols in leaves indicated that ozone reduced total soluble phenol content, especially contents of agrimoniin, pedunculagin, and GE-56 in both cultivars. The effect of ozone fumigation differed from changes in soluble phenol content related to leaf ageing. The latter process resulted not only in a reduction of almost all soluble phenols but also in an increasing percentage of the flavonoid components. The reduction of gallic acid derivatives and ellagitannins in ozone-treated leaves may be explained by a shortage of their precursor substances phosphoenolpyruvate and erythrose-4-phosphate or by a consumption of soluble phenols in response to ozone stress. Zusammenfassung Erdbeerpflanzen der Sorten 'Elsanta' und 'Korona' wurden drei Monate lang fünf Tage pro Woche in einer Atmosphäre von 65 ppb Ozon angezogen. Analysen der löslichen Phenole ergaben, dass Ozon die Konzentration aller löslichen Phenole absenkte, jedoch besonders die von Agrimoniin, Pedunculagin und GE-56 in beiden Sorten. Die Auswirkungen der Ozonbegasung auf die Phenolgehalte unterschieden sich von Blattalterungsprozessen. Letztere bewirkten nicht nur eine Konzentrationsabsenkung sämtlicher löslichen Phenole sondern auch einen steigenden Prozentanteil an Flavonoiden. Die Konzentrationsabnahme der Gallussäurederivate und Ellagitannine in mit Ozon gestressten Blättern kann sowohl auf eine Unterversorgung mit den Vorläufersubstanzen Phosphoenolpyruvat und Erythrose-4-Phosphat zurückgeführt werden als auch mit einem Verbrauch löslicher Phenole in Folge eines Ozonstresses erklärt werden.
Acta horticulturae, May 1, 2003
In a two-year study, strawberry (Fragaria X ananassa Duch.) cvs 'Elsanta' and 'Korona' showed dif... more In a two-year study, strawberry (Fragaria X ananassa Duch.) cvs 'Elsanta' and 'Korona' showed differences in their sensitivities to salinity as applied by irrigating plants with nutrient solutions with 30 mM or 60 mM NaCl concentration. One month after start of treatments, necrotic symptoms appeared on leaf margins of 'Elsanta'. 'Korona' leaves, however, showed any to few symptoms. During the first growing season, salinity impaired the growth of 'Elsanta' leaves as indicated by a reduction in leaf area, leaf expansion rate and dry weight. During the second season, the reduction in leaf growth was more severe. By comparison, growth of 'Korona' leaves was reduced only during the second season. Total leaf number was unaffected by salinity in both cultivars; however, the number of dead leaves increased significantly due to salinity in 'Elsanta', but remained fairly unchanged in 'Korona'. Maximum assimilation rates and carboxylation efficiencies, calculated from the A/C i curves of leaves, were reduced by 39% and 44% in 'Elsanta' and by 22% and 34% in 'Korona', respectively. The net photosynthetic rate of 'Elsanta' was slightly reduced in tendency by salt treatments, while in 'Korona' the reduction was significant at the highest salt treatment. Salinity had no effect on the Na + content in leaves of both cultivars. However, the leaf Clcontent increased with increasing salt level, reaching maximum value in 'Elsanta' leaves treated with the highest salt level. This indicates that the effect of salt on leaves was due to Cl-, not to Na +. Root Na + content increased with salinity in both cultivars. The increase in root Clcontent in 'Elsanta' was not significant, but it rose in tendency. Clcontent in 'Korona' roots increased significantly with increasing salt level. This suggest that 'Korona' strawberry is able to accumulate absorbed Clin root tissues, thus preventing the translocation of this toxic ion to the leaves.
Journal of Plant Physiology, 1997
Gas exchange, chlorophyll fluorescence parameters, and macronutrient contents were investigated i... more Gas exchange, chlorophyll fluorescence parameters, and macronutrient contents were investigated in young «3weeks), medium (4-6weeks) and old (7-9weeks) strawberry leaves growing at 300, 450, 600, 750, and 900 ppm CO 2 • An increase of the CO 2 level to 600 ppm promoted leaf net photosynthesis, but a further rise led to a decrease of net CO 2 assimilation. The reduction of net photosynthetic rate was less distinct in young leaves exposed to CO 2 levels above 600 ppm for less than 3 weeks, indicating that the reduction might depend on the period of exposition or leaf age. Transpiration and stomatal conductance were significantly affected by leaf age, but not by CO 2 concentrations. Medium leaves were characterised by a higher transpiration rate and stomatal conductance than young and old ones. In leaves growing at high CO 2 levels ChI a and b contents as well as the alb ratio decreased. The contents ofN, P, K, Ca and Mg were lower in leaves growing at high CO 2 concentrations than in those at low ones. An elevated CO 2 level above 750 ppm led to a general macronutrient deficiency and was accompanied by a distinct decrease of optimal quantum yield, due to a rise of basal fluorescence, and an increase of non-photochemical energy dissipation in old leaves.
日本植物生理学会年会およびシンポジウム 講演要旨集 第45回日本植物生理学会年会講演要旨集, Mar 27, 2004
Agriculture, Sep 19, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Neues Jahrbuch für Geologie und Paläontologie, Feb 26, 2021
Photosynthetica, May 28, 2020
Evidence that the green fluorescence protein (GFP) develops a significant toxicity in plants has ... more Evidence that the green fluorescence protein (GFP) develops a significant toxicity in plants has not been found, but it may represent a source of free radicals as a consequence of its fluorescence. In addition, green light is known to trigger the acclimatisation of the photosynthetic system towards a shady environment. Moreover, the light-harvesting system may acclimate to an increased availability of green light. Each of these effects may be induced by the GFP. Therefore, the hypothesis was tested, whether transformation of Nicotiana tabacum cv. Bursan to express the GFP could affect chlorophyll fluorescence parameters. The analysis revealed a significantly lower absorption of energy per excited cross section in GFP-transformed tobacco, a lower number of active reaction centres per excited cross section, a larger absorption and trapped energy flux leading to the reduction of the primary quinone electron acceptor of PSII per reaction centre, and a lower variable fluorescence.
The South African Journal of Plant and Soil, 1998
Soil respiration is a major contributor to the carbon flux in apple orchards, but very little dat... more Soil respiration is a major contributor to the carbon flux in apple orchards, but very little data exist for citrus. Daytime soil respiration, grass respiration, and grass photosynthesis were recorded in a 'Nules' clementine (Citrus reticulata Blanco) orchard on 'Carrizo' citrange or 'X639' rootstock in Stellenbosch, Republic of South Africa, under typically variable spring weather conditions such as cool to hot, and clear to cloudy days. The amount of CO 2 contributed by the citrus roots and the Oakleaf soil type to the carbon fluxes in the orchard, was evaluated. Soil respiration rate in the citrus rows varied between 0.1 and 0.4 g CO 2 m-2 h-1 and increased with temperature, with a Q10 of about 1.4. After rainfall or irrigation, soil respiration was higher, especially at elevated temperatures. The rootstocks 'Carrizo' and 'X639' were characterised by slightly different rates of soil respiration. The difference was more pronounced after irrigation, and soil respiration of 'X639' exceeded that of 'Carrizo' by 0.03 to 0.04 g CO 2 m-2 h-1. Grass respiration between the rows ranged from 0.7 to 1.4 g CO 2 m-2 h-1 and grass net photosynthesis exceeded 1.0 g CO 2 m-2 h-1 , indicating that the grass strips between the tree rows act as a sink for CO 2 during the light period. It was concluded that soil respiration represents a major source of CO 2 in a citrus orchard.
Herba Polonica, Dec 1, 2015
Introduction: Allium ursinum L. has a commercial value due to its high contents of bioactive comp... more Introduction: Allium ursinum L. has a commercial value due to its high contents of bioactive compounds and mild, garlic-like taste. In vitro culture played an important role in obtaining Allium species with the desired characteristics and in the production of healthy reproductive material. Objective: Developing an effective method of sterilization bear's garlic bulbs. Methods: To obtain sterile shoots of garlic several methods of sterilization involving such factors as ACE, H 2 O 2 , HgCl 2 , and UV-C were tested. Results: In order to obtain sterile shoots of bear's garlic, several sterilization procedures were tested. The best procedure was based on a two-step disinfection, where the whole onions were treated with ethanol and H 2 O 2 for 20 min. Thereafter, the isolated apical buds were sterilized in ACE for 10 min, rinsed in double-distilled water and transferred onto MS medium for growing. Up to 95% of the inoculated explants formed shoots, which were sub-cultured on MS with 4 mg dm-3 BAP in order to enable further propagation. Conclusion: After optimization and stabilization, this procedure may become the basic concept of a proper and reliable propagation method of bear's garlic on commercial scale.
Acta horticulturae, May 1, 2003
The present investigation was aimed at assessing the response of 'Elsanta' and 'Korona' strawberr... more The present investigation was aimed at assessing the response of 'Elsanta' and 'Korona' strawberry plants to three levels (0, 40 and 80 meq/L) of NaCl-salinity stress and to describe salt effects on fruit quality. The investigated cultivars differed in their sensitivity to NaCl salinity. Typical stress symptoms such as leaf necroses, growth retardation and a poor fruit yield were observed in both cultivars, but 'Elsanta' was more sensitive than 'Korona'. In both cultivars, salt stress lowered the concentration of titratable acids in the fruit. In 'Elsanta', the content of soluble solids was reduced, while that of proteins increased. Vitamin C and E contents of fruits remained fairly stable as did relative dry matter in both cultivars.
Scientia Horticulturae, 2002
A/C i and photosynthetic light response curves for gas exchange characteristics were measured for... more A/C i and photosynthetic light response curves for gas exchange characteristics were measured for spur leaves of 25-year-old 'Golden Delicious' and 'Granny Smith' apple trees (Malus domestica Borkh.) to investigate their acclimation capacity to a shade-to-sun transition in a commercial apple orchard. Spur leaves of both cultivars adapted to summer-pruning within 2 weeks, regardless of the time of the season at which pruning was conducted. There were no significant differences between the spur leaves of later pruned trees and corresponding leaves on trees that were continuously pruned during the summer period in terms of net photosynthetic rate and carboxylation efficiency, for both cultivars. The shape of the photosynthetic light response curves also proved the acclimation potential of both cultivars to shade-to-sun transitions. The rapid increase of the chlorophyll a/b ratio after pruning indicated that the acclimation of the photosynthetic system to avoid over-excitation of the photosynthetic reaction centers occurred within 1 week. Nevertheless, leaf dry mass per leaf area was intermediate between 'continuous summer-pruning' and 'no-pruning' treatments for leaves on later pruned trees, indicating that the acclimation to shade-to-sun transitions was not perfect in either cultivar. The present data also Scientia Horticulturae 92 (2002) 9-27 Abbreviations: A, net photosynthetic rate; A max , maximum photosynthetic rate; C i , intercellular CO 2 concentration; Chl, chlorophyll; g 0 m , carboxylation efficiency; g s , stomatal conductance; l, stomatal limitation; PPFD, photosynthetic photon flux density
Scientific Reports
Perennial ryegrass is a grass species used to establish lawns in urban areas where pollution is a... more Perennial ryegrass is a grass species used to establish lawns in urban areas where pollution is a major environmental problems. Cadmium (Cd) and nickel (Ni) contribute significantly to these pollutants and may cause photosynthetic limitation. The main objective of this work was to perform a comprehensive analysis of photosynthetic efficiency of perennial ryegrass seedlings under Cd and Ni stress. Some of the main indices of photosynthetic efficiency (prompt and delayed chlorophyll-a fluorescence signals and modulated reflectance at 820 nm) were compared with growth parameters. Two cultivars were tested: 'Niga' and 'Nira'. A decrease in photosystem (PS) II and PSI activity was observed. This was due to an increase in nonradiative dissipation of the PSII antenna, a decrease in PSII antenna size, or a decrease in the number of photosynthetic complexes with fully closed PSII RCs. Efficiency of electron transport was decreased. The effect on the modulated reflectance sign...
Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen
Two-week-old strawberry (Fragaria x ananassa Duch. cv. 'Elsanta') plants were acc... more Two-week-old strawberry (Fragaria x ananassa Duch. cv. 'Elsanta') plants were acclimatized to 300, 450, 600, 750 or 900 ppm CO2 in controlled environment chambers for 50 days. An elevated CO2 concentration enhanced up to 750 ppm total chlorophyll a and chlorophyll b contents as well as the a/b ratio. Long-term CO2 enrichment induced leaf senescence and decreased photosynthetic efficiency as well as photochemical conversion efficiency of PS II. Intercellular CO2 concentration significantly increased with CO2 enrichment. Stomatal conductance, transpiration rate, and net photosynthesis rate of young leaves increased with raising CO2 concentrations. However, CO2 levels above 600 ppm markedly reduced net photosynthetic rate of adult and old leaves. High CO2 concentrations up to 900 ppm did not significantly affect dark respiration rate of the leaves. Photosynthetic water-use efficiency was highest in old leaves and lowest in young one. Increased CO2 concentrations up to 600-750 ppm improved leaf photosynthetic capacity by increasing photosynthetic water-use efficiency.