Natural and commercial Salix clones differ in their ecophysiological response to Zn stress This study was carried out to determine the effect of different zinc concentrations on the ecophysiological response of Salix clones: four commercial clones (“1962”, “1968”, “Drago”, and “Levante”) selected for short rotation coppice, and one natural clone, “Sacco”, obtained from a contaminated area. Gas exchanges, chlorophyll a fluorescence (JIP-test), relative chlorophyll content, and biometric parameters were measured in plants grown for fifteen days in soil containing Zn concentrations of 0, 300, 750, and 1,500 mg(ZnCl2) kg-1. Ecophysiological response to metal stress differed in dependence on the Zn concentration and clone. At the low Zn concentration (300 mg kg-1), the absence of any significant reductions in parameters investigated indicated an efficient plant homeostasis to maintain the metal content within phytotoxic limits. Stomatal limitation, observed at 750 and 1,500 mg kg-1, which was found in all clones after three days of the treatment, might be caused by indirect effects of metal on guard cells. Among commercial clones, “Drago” was more sensitive to Zn stress, showing inhibition of growth, while “1962” clone showed a downregulation of PSII photochemistry following the slowdown in the Calvin-Benson cycle. On the contrary, the natural Salix clone (“Sacco”) performed better compared to the other clones due to activation of a photosynthetic compensatory mechanism., A. Bernardini, E. Salvatori, S. Di Re, L. Fusaro, G. Nervo, F. Manes., and Obsahuje seznam literatury
Natural occurrence of C4 species, life form, altitude pattern, and infection by the Three Gorges Project (TGP) were studied in the TGP region. 76 species (about 2.5 % of the total 2 685 vascular plant species in the region), in 6 families and 42 genera, were identified with C4 photosynthesis. 91 % of these C4 species belong to Monocotyledoneae, e.g. Cyperaceae (14 species), Gramineae (54 species), and Commelinaceae (1 species). Of these C4 species, Gramineae was the leading C4 family: 54 C4 grass species (71 % of the total C4 species), about 36 % of the total grasses, were identified in the TGP region. 98 % C4 species was found in therophyte (55 %) and hemicryptophyte (43 %). This is consistent with high grass and sedge compositions in the region. Most habitats of more than a half of these C4 species (65 %) will be submerged permanently, but no species will be endangered or extinct, because 95 % C4 species can be found from 500 to 800 m above sea level. The abundance of some C4 species will be dropped due to the reduction of distribution scope. It will take a long-term to explore the effects of the TGP on plants, vegetation, and environment.
The photosynthetic activities of three planktonic desmid species (Staurastrum brachiatum, Staurodesmus cuspidatus var. curvatus, and Staurastrum chaetoceras) were compared after adaptation to medium enriched with either a 20 mM Na+-phosphate (P) or HEPES buffer. Incubations up to 2 d were carried out at pH 6 or 8 under normal air or air enriched with 5 % CO2. Gross maximum photosynthetic rate (Pmax) and growth rate were decreased in both S. brachiatum and Std. cuspidatus at higher pH when using the HEPES buffer and this effect was independent of CO2 concentration, indicating that pH had an inhibitory effect on photosynthesis and growth in these species. The P-buffer at pH 8 caused a large decrease in Pmax and quantum yield for charge separation in photosystem 2 (PS2), compared to HEPES-buffered algae. This effect was very large in both S. brachiatum and Std. cuspidatus, two species characteristic of soft water lakes, but also significant in S. chaetoceras, a species dominant in eutrophic, hard water lakes. The decreased Pmax in P-buffer could not be related to a significant increase in cellular P content known to be responsible for inhibition in isolated chloroplasts. Experiments at pH 6 and 8 showed that two conditions, high pH and high Na+ concentration, both contributed to the decreased Pmax and quantum yield in the desmids. Effects of a P-buffer were less pronounced by using K+-P buffer. The use of P-buffer at pH 8 possibly resulted in high irradiance stress in all species, indicated by damage in the PS2 core complex. In the soft water species pH 8 resulted in increased non-photochemical quenching together with a high de-epoxidation state of the xanthophyll cycle pigments. and E. Spijkerman ... [et al.].
The oldest translation into Czech of Eneas Silvius Piccolomini´s Historie česká (Historia Bohemica) was completed in 1487 by Uherský Brod vicar Jan Húska, though the autograph of Húska´s translation has not been preserved; it is only known from a single copy in Vatican Library manuscript Reg. lat. 601, produced in the early 16th century. This study gives a detailed codicological description of this manuscript and attempts to find its story before it was taken from Bohemia to Sweden in the mid-17th century as war booty and thence to Rome as part of Queen Christina´s library.
This article presents a brief summary of research results on handwritten newspapers preserved in book and archive fonds in Vienna and Dresden. The research focused on handwritten newspapers from Prague, with the emphasis in particular on the period between 1583 and 1612, when Prague was Rudolf II's city of residence. At that time it was one of the most important European cenres of news reporting, conveying reports from the entire known world at that time.
Net CO2 uptake rates (PN) were measured for the vine cacti Hylocereus undatus and Selenicereus megalanthus under relatively extreme climatic conditions in Israel. Withholding water decreased rates and the daily amount of CO2 uptake by about 10 % per day. Compared with more moderate climates within environmental chambers, the higher temperatures and lower relative humidity in the field led to a more rapid response to drought. The upper envelopes of scatter diagrams for PN versus temperature for these Crassulacean acid metabolism species, which indicate the maximal rates at a particular temperature, were determined for both night time CO2 uptake in Phase I (mediated by phosphoenolpyruvate carboxylase, PEPC) and early morning uptake in Phase II (mediated by ribulose-1,5-bisphosphate carboxylase/oxygenase, RuBPCO). As stem temperature increased above 13 °C, the maximal PN increased exponentially, reaching maxima near 27 °C of 12 and 8 μmol m-2 s-1 for Phases I and II, respectively, for H. undatus and 6 and 4 μmol m-2 s-1, respectively, for S. megalanthus. Based on the Arrhenius equation, the apparent activation energies of PEPC and RuBPCO were 103 and 86 kJ mol-1, respectively, for H. undatus and 77 and 49 kJ mol-1, respectively, for S. megalanthus, within the range determined for a diverse group of species using different methodologies. Above 28 °C, PN decreased an average of 58 % per °C in Phase I and 30 % per °C in Phase II for the two species; such steep declines with temperature indicate that irrigation then may lead to only small enhancements in net CO2 uptake ability. and J. Ben-Asher ... [et al.].
The responses of rates of net photosynthesis (F^) to photosynthetic photon fluence rate (i), leaf temperature and CO2 were studied inhalf-sib families of greenhouse and field grown black locust (Robinia pseudoacacia L.) seedlings. The response of to 1 was similar in both greenhouse and field grown seedlings, except the quantum yields were lower in the field grown seedlings. The saturáting / was as low as 600 pmol m'^ s'’ in some seedlings but did not saturate at 1900 púiol m'^ s'^ in others. The optimum temperature for in field grown seedlings was shghtly lower than the greenhouse grown seedlings. increased rapidly with increased CO2 up to 350 pmol mol'^ but beyond SOO pmol mol'* the increase was gradual in some families. On average, stomata represented only 23 % of the limitation to Pii with no differences between families observed. Family x I, family x temperature and family X CO2 were not significant for Pj^.