The basic slow Idnetics and spectral properties of the chlorophyll fluorescence temperature curve (FTC) under low actinic radíation excitation (s 2 W m"2) were measured in primary barley leaves of shade-grown plants. In contrast to the usual Fo temperature dependence, two distinct regions and two maxima of FTC were documented upon a linear heating regime. The fírst maximum situated between 49.5 and 51 °C was less sensitive, whereas Ihe position of the second maximum (between 53 and 63 “C) was strongly dependent on the heating rate. The spectral resolution of the fluorescence emission suggested a presence of photosystem (PS) 1 emission in the FTC at 436 nm excitation and an efíect of partial light-harvesting complex LHCII disconnection from the PS 2 complex at 480 nm excitation. A new fluorescence emission around 700 nm appeared upon heating. The excitation spectra in the 400 nm to 500 nm region for the 685 nm fluorescence emission wavelength indicated that only one emission form was responsible for both of the FTC bands. The 77 K fluorescence spectra at increasing, maximal and decreasing parts of Ihe second FTC band were measured using the triggering expeiiments wilh an incubation temperature of 58 oC. A disconnection of LHCI firom otiier pigment-protein complexes is suggested as a concomitant effect of Ihe second FTC maximum.
In our earlier works, we have identified rate-limiting steps in the dark-to-light transition of PSII. By measuring chlorophyll a fluorescence transients elicited by single-turnover saturating flashes (STSFs) we have shown that in diuron-treated samples an STSF generates only F1 (< Fm) fluorescence level, and to produce the maximum (Fm) level, additional excitations are required, which, however, can only be effective if sufficiently long Δτ waiting times are allowed between the excitations. Biological variations in the half-rise time (Δτ1/2) of the fluorescence increment suggest that it may be sensitive to the physicochemical environment of PSII. Here, we investigated the influence of the lipidic environment on Δτ1/2 of PSII core complexes of Thermosynechococcus vulcanus. We found that while non-native lipids had no noticeable effects, thylakoid membrane lipids considerably shortened the Δτ1/2, from ~ 1 ms to ~ 0.2 ms. The importance of the presence of native lipids was confirmed by obtaining similarly short Δτ1/2 values in the whole T. vulcanus cells and isolated pea thylakoid membranes. Minor, lipid-dependent reorganizations were also observed by steady-state and time-resolved spectroscopic measurements. These data show that the processes beyond the dark-to-light transition of PSII depend significantly on the lipid matrix of the reaction center.
Determination of modulated chlorophyll fluorescence coupled to measurements of the net photosynthetic rate (P^) leaf water potential has heen assessed as a screening method to score a set of twenty genotypes of barley {Hordeum vulgare L.) for drought tolerance. These methods can be ušed as rapid screening tests for water stress tolerance in barley, although applied alone they are appropriate indicators for a severe water stress. For genotypes growing under a mild water stress, it is necessary to use several screening tests simultaneously. Drought tolerant genotypes show smaller variations of photochemical quenching, P^, water use efficiency and leaf temperature than the drought sensitive ones.
Pojem neutrina se objevil ve fyzikální literatuře v roce 1930. Nejprve to byla pouhá hypotéza, později se z ní stala pracovní hypotéza při popisu některých rozpadů částic, a teprve o mnoho let později, po dvaceti pěti letech, byla existence neutrina empiricky prokázána., Antonín Vančura., and Obsahuje seznam literatury a 8 dodatků
The article presents a review of the research activities of the Socio-Economics of Housing research team. The Socio-economics of Housing team is one of the research teams at the Institute of Sociology of the Academy of Sciences of the Czech Republic. The main research activities of the team include sociological research concerning attitudes towards housing in the Czech Republic, international comparisons of housing policies and social housing systems, and econometric simulations of policy reforms, like rent deregulation, the introduction of housing allowance and social housing, housing finance, housing market efficiency, and house price indices.