Forty-four genotypes from the rice germplasm were identified under photoinhibition/photooxidation and shade conditions and divided into four basic types: (1) cultivars tolerant to both photooxidation and shading, (2) cultivars tolerant to photooxidation but sensitive to shading, (3) cultivars tolerant to shading but sensitive to photooxidation, and (4) cultivars sensitive to both photooxidation and shading. Photosynthetic characteristics of a cultivar tolerant (cv. Wuyugeng 3) and a cultivar sensitive (cv. Xiangxian) to photooxidation and shading were compared. The photochemical efficiency (Fv/Fm) of photosystem 2 (PS2) and the content of PS2-D1 protein in the tolerant cultivar Wuyugeng 3 decreased less under photooxidative conditions as compared with Xiangxian. Under similar conditions, superoxide dismutase was induced rapidly to a higher activity and the active oxygen (O-) built up to a lower level in Wuyugeng 3 than in Xiangxian. Net photosynthetic rate (PN) decreased by 23 % in Wuyugeng 3 vs. 64 % in Xiangxian. Shading (80 %) during the booting stage caused only small decreases (7-13 %) in ribulose-1,5-bisphosphate carboxylase activity and PN in Wuyugeng 3 but severe decreases (57-64 %) were observed in Xiangxian which corresponded to the decreases in grain yield of the two cultivars (38 and 73 %, respectively). We described a simple and effective screening method and physiological basis for breeding crops for enhanced tolerance to both high and low irradiance. and Demao Jiao, Xia Li.
Cotton (Gossypium hirsutum L.) yields are impacted by overall photosynthetic production. Factors that influence crop photosynthesis are the plants genetic makeup and the environmental conditions. This study investigated cultivar variation in photosynthesis in the field conditions under both ambient and higher temperature. Six diverse cotton cultivars were grown in the field at Stoneville, MS under both an ambient and a high temperature regime during the 2006-2008 growing seasons. Mid-season leaf net photosynthetic rates (PN) and dark-adapted chlorophyll fluorescence variable to maximal ratios (Fv/Fm) were determined on two leaves per plot. Temperature regimes did not have a significant effect on either PN or Fv/Fm. In 2006, however, there was a significant cultivar × temperature interaction for PN caused by PeeDee 3 having a lower PN under the high temperature regime. Other cultivars' PN were not affected by temperature. FM 800BR cultivar consistently had a higher PN across the years of the study. Despite demonstrating a higher leaf Fv/Fm, ST 5599BR exhibited a lower PN than the other cultivars. Although genetic variability was detected in photosynthesis and heat tolerance, the differences found were probably too small and inconsistent to be useful for a breeding program., W. T. Pettigrew., and Obsahuje bibliografii
Obsah: F. Kavka: La Bohême hussite et les projets de paix de Georges de Podiěbrad; F. Seibt: Die hussitische Revolution und die europäische Gesellschaft; J. Irmscher: Die Gestalt Georgs von Poděbrad im deutschen historischen Lied; V. Vaněček: Le projet du roi Georges sous l'aspect de l'histoire du droit; R. Bierzanek: Les nouveaux éléments politiques et sociaux dans le projet du roi Georges Podiébrad; J. Kejř: Manuscrits, éditions et traductions du projet; F.G. Heymann: International Relations in Mid-fifteenth Century Europe and Their Significance for the Peace Plan of King George; R. Heck: Polen und das Friedensprojekt Georgs von Podiebrad; V.L. Tapié: Le projet pacifique de Georges et la politique française: V. Outrata: Some Legal Principles Reflected in the Project and Their Historical Perspective; T. Kardos: Die Ideen des Humanismus und des allgemeinen Friedens; E. Winter: vom Defensor pacis des Marsilius von Padua (1324) bis zum Amator pacis Georg von Podiebrad (1464); V.M. Koreckij: Projekt Irži Podebrada ob organizacii mira i sovremennost'; F. Šmahel: Problěmes rattachés aux recherches sur le projet pacifique du roi Georges; R. Kalivoda: Die hussitische Revolution und die Podiebrader Epoche; L.P. Lapteva: Epocha Irži iz Podebrad v russkoj dorevoljucionnoj istoriografii; M. Horvat: Comparaison des projets de paix de Georges de Podiébrad avec les projets précé dents et suivants.
After exposing one half of a low light-adapted kidney bean (Phaseolus vulgaris) leaf to high light, parameters of chlorophyll (Chl) a fluorescence, such as PSII operating efficiency, PSII maximum efficiency under light, and photochemical quenching, decreased in the opposite half of the same leaf, whereas the capacity of the cyanide-resistant respiratory pathway significantly increased. When one half of the low light-adapted leaf was exposed to low light, the opposite half pretreated with 1 mM salicylhydroxamic acid (SHAM, an inhibitor of the cyanide-resistant respiratory pathway) did not exhibit significant changes in the Chl fluorescence values compared with the without SHAM pretreatment. However, after exposing one half of the low light-adapted leaf to high light, the opposite half pretreated with 1 mM SHAM showed lower Chl fluorescence values than that without SHAM pretreatment. Our results indicate that partial exposure of the low light-adapted leaf to high light can impose a systemic stress on the PSII photochemistry. The enhanced capacity of the cyanide-resistant respiratory pathway may be involved in the maintenance of the photosynthetic performance in the leaf tissues experiencing high light-induced systemic stress., H.-Q. Feng, S.-Z. Tang, K. Sun, L.-Y. Jia, R.-F. Wang., and Obsahuje bibliografii
The fundamental cause of down-regulation of photosynthesis at elevated carbon dioxide concentration (EC) is thought to be a slower rate of utilization of saccharides than their stimulated rate of production, but there are few studies directly supporting this idea under field conditions. We hypothesized that within Brassica oleracea, down-regulation would not occur in kohlrabi because it has a large sink for saccharides in an enlarged stem, but would occur in collards, which lack this sink. Field tests were consistent with this hypothesis. In collards, the degree of down-regulation of photosynthesis in plants grown at EC varied depending on the daily integral of photosynthetically active radiation (PAR) of the day prior to the measurement of photosynthetic capacity, as did leaf saccharide content. However, EC did not result in lower leaf contents of chlorophyll, soluble protein, ribulose-1,5-bisphosphate carboxylase, or nitrate in collards, nor was there any evidence of a triose phosphate utilization rate limiting photosynthesis. Experiments in controlled environment chambers confirmed that there was a threshold response for the down-regulation of photosynthesis in collards at EC to the PAR of the previous day, with down-regulation only occurring above a minimum daily integral of PAR. Down-regulation of photosynthesis could be induced in plants grown at ambient carbon dioxide by a single night at low temperature or by a single day with high PAR and EC. In the controlled environment study, the degree of down-regulation of photosynthesis was highly correlated with leaf glucose, fructose, and sucrose contents, and less well correlated with starch content. Hence down-regulation of photosynthesis at EC in collards in the field represented feedback inhibition from the accumulation of soluble saccharides and day-to-day variation in its occurrence was predictable from the weather. and J. A. Bunce, R. C. Sicher.
The negative effects of continuous light (CL) seen in tomato plants are often claimed to be linked to effects of offsetting the diurnal rhythm. In this study we tested whether a short-term daily temperature drop prevents the decreased photosynthetic performance seen in tomato plants grown under CL. Tomato (Lycopersicon esculentum Mill.) plantlets were grown at constant temperature of 26°C under 16-h day (16D) or 24-h day (24D) at 150 μmol m-2 s-1 PPFD. Some 24D plants were treated daily by 2 h temperature drop from 26 to 10°C (24D+DROP). Physiological disorder, such as severe leaf chlorosis, a large decrease in net photosynthetic rate, maximal quantum yield of PSII photochemistry, and the effective quantum yield of PSII photochemistry were observed in 24D, but not in 16D and 24D+DROP plants. The daily 2-h drop in temperature eliminated a negative effect of CL on photosynthesis and prevented the development of leaf chlorosis in tomato plants. This could be due to a change in carbohydrate metabolism as the short drop in temperature might allow maintenance of the diurnal rhythms., E. N. Ikkonen, T. G. Shibaeva, E. Rosenqvist, C.-O. Ottosen., and Obsahuje seznam literatury
Daily variations of primary production and dependence of net photosynthetic rate (Ejm) on Írradiance (/) in seaweeds and seagrass Thalassodendron ciliatum inhabiting 0-52 m depths off sbore of the Seychelles Islands were studied by oxygen measurements in a flow systém under conditions close to the natural ones. The obtained curves displayed one maximum coiresponding to the daily maximum I. Saturation of P-^ by 1 was not observed even with intertidal macrophyte species. All the macrophytes studied exhibited daily variations in the shape of the P-1 curves. The I saturated photosynthetic rate {P) (4), maximum photosynthetic rate {P^, and the initial slope of the P-1 curve (a) increased from moming to midday and decreased towards evening. P in the macroalgae and seagrass was inhibited considerably by more than 280 pmol m"2 s'* photon flux densities (PFD) of photosynthetically active radiation (PAR) only in the evening. Thus in tropical waters of the Seychelles Islands radiant energy is the main factor limiting production of macrophyte communities in nátuře.
To investigate damaging mechanisms of chilling and salt stress to peanut (Arachis hypogaea L.) leaves, LuHua 14 was used in the present work upon exposure to chilling temperature (4°C) accompanied by high irradiance (1,200 μmol m-2 s-1) (CH), salt stress accompanied by high irradiance (1,200 μmol m-2 s-1) (SH), and high-irradiance stress (1,200 μmol m-2 s-1) at room temperature (25°C) (NH), respectively. Additionally, plants under low irradiance (100 μmol m-2 s-1) at room temperature (25°C) were used as control plants (CK). Relative to CK and NH treatments, both the maximal photochemical efficiency of PSII (Fv/Fm) and the absorbance at 820 nm decreased greatly in peanut leaves under CH and SH stress, which indicated that severe photoinhibition occurred in peanut leaves under such conditions. Initial fluorescence (F0), 1 - qP and nonphotochemical quenching (NPQ) in peanut leaves significantly increased under CH- and SH stress. Additionally, the activity of superoxide dismutase (SOD), one of the key enzymes of water-water cycle, decreased greatly, the accumulation of malondialdehyde (MDA) and membrane permeability increased. These results suggested that damages to peanut photosystems might be related to the accumulation of reactive oxygen species (ROS) induced by excess energy, and the water-water cycle could not dissipate energy efficiently under the stress of CH and SH, which caused the accumulation of ROS greatly. CH and SH had similar damaging effects on peanut photosystems, except that CH has more severe effects. All the results showed that CH- and SH stress has similar damaging site and mechanisms in peanut leaves. and L.-Q. Qin ... [et al.].
Edice německo-česko-latinské cechovní knihy pražských malířů a štítařů z let 1348-1527 s německým historicko-kodikologickým úvodem a poznámkami pod textem edice., Rukopis, jehož edice jest obsahem této knihy, byl darován hr. Kašparem Šternberkem r. 1802 Společnosti vlasteneckých přátel umění, předchůdkyni dnešní Národní galerie v Praze (s. 2). Úvod dále seznamuje čtenáře nejen s vlatními dějinami cechu, ale i s lingvistickými proplémy při luštění jeho německého i českého textu. Vlastní edice (s. 61-97) přináší k roku založení cechu (r. 1348) cechovní statuta v paralenmí středohornoněmeckém a českém znění. Zápisy - vesměs latiské nebo české - k dalším rokům zaznamenávají jak usnesení cechovních schůzí, včetně změn stanov, tak i dobové přehledy jeho členů., Oborové slovníky, encyklopedie, bibliografie., Osobnosti., Dějiny., and Autoři komentářů:
Pangerl, Matthias, 1834-1879 ;
Woltmann, Alfred, 1841-1880