On 19th February 2016 exactly 100 years passed since the death of Ernst Mach, the great physicist and philosopher of the 19th and 20th centuries, a native of Brno-Chrlice. On the occasion of this anniversary, Masaryk University and other institutions organised Ernst Mach Brno-Days 2016 with the conference "Ernst Mach: Physics - Philosophy - Technics" and other events. The presented brief report informs about these events. and Jana Musilová.
The contents of chlorophyll (Chl), leaf biomass, and soluble proteins were markedly decreased in phytoplasma infected apple leaves. Similar results were also observed for ribulose-1,5-bisphosphate carboxylase, 14CO2 fixation, and nitrate reductase activity. In contrast, the contents of sugars, starch, amino acids, and total saccharides were significantly increased in phytoplasma infected leaves. In isolated chloroplasts, phytoplasma infection caused marked inhibition of whole photosynthetic electron chain and photosystem 2 (PS2) activity. The artificial exogenous electron donor, diphenyl carbazide, significantly restored the loss of PS2 activity in infected leaves. Similar results were obtained when Fv/Fm was evaluated by in vivo Chl a fluorescence kinetic measurements. and M. Bertamini ... [et al.].
We examined the effects of foliar application of various nitrogen (urea) concentrations on gas-exchange and chlorophyll (Chl) fluorescence characteristics in bean plants treated by heat stress (42/30°C, day/night temperatures). Heat stress caused reductions in contents of Chl a, Chl b, and in maximum photochemical efficiency of PSII by 13, 20, and 27%, respectively, regardless of the N treatment. However, N fertilization caused significant increases in these parameters, especially at higher N concentrations. The net photosynthetic rate and stomatal conductance were enhanced by 32, 60, and 69% and by 25, 88, and 100% due to addition of 5, 10, and 15 mM N, respectively. However, gas-exchange parameters were reduced by 24% due to heat stress. N fertilization alleviated adverse effects of heat stress., I. A. Hassan, H. M. Abou Zeid, W. Taia, N. S. Haiba, A. Zahran, R. H. Badr, R. A. El Dakak, E. A. Shalaby., and Obsahuje bibliografii
Forty two-month-old plants of Dalbergia sissoo and D. latifolia were subjected for 56 d to water deficit induced by withholding water. Drought stress caused a significant reduction in plant height, stem diameter, net photosynthetic rate (PN), transpiration rate (E), and stomatal conductance (gs) in both species, but the reduction was greater in D. sissoo than in D. latifolia. Water use efficiency (PN/E) was adversely affected due to water stress only in D. latifolia, and intrinsic water use efficiency (PN/gs) was increased in both species. There was a slight effect of water stress on variable to maximum fluorescence (Fv/Fm) (quantum yield of photosystem 2) in both species, but the species did not differ significantly in this attribute. and M. Ashraf ... [et al.].
Chlorophyll fluorescence measurements showed that plasticity to salinity in stems of Salicornia ramosissima is expressed at a modular level, so intraplant variation should be considered in further studies. and S. Redondo-Gómez ... [et al.].
Alkalies are important agricultural contaminants complexly affecting plant metabolism. In this study, rice seedlings were subjected to alkaline stress (NaHCO3:Na2CO3 = 9:1; pH 8.9) for 30 days. The results showed that stress mightily reduced net photosynthetic rate (PN), but slightly decreased transpiration rate and stomatal conductance. This indicated that decline of PN might be a result of nonstomatal factors. Alkaline stress caused a large accumulation of Na+ in leaves up to toxic concentration, which possibly affected chloroplast ultrastructure and photosynthesis. We found that alkaline stress reduced chlorophyll fluorescence parameters, such as ratios of Fv′/Fm′, Fv/Fm, photosystem (PS) II efficiency, and electron transport rates in rice plants, i.e. it influenced the efficiencies of photon capture and electron transport by PSII. This might be a main reason for the decrease of PN under such conditions. Deficiency of minerals could be another reason for the decline of PN. Alkaline stress lowered contents of N, K, Cu, Zn, P, and Fe in rice plants. In addition, the stress strongly affected metabolism of amino acids. This might be caused by imbalance in carbon metabolism as a result of photosynthesis reduction., Z.-H. Wu, C.-W. Yang, M.-Y. Yang., and Obsahuje bibliografii
In this article we present study of proper motions of the flare active reglons NOAA/USAF 3885 and NOAA/USAF 3886. The 30 flare of 3 - 4 September 1982 (NOAA 3886) appeared to have a close relation
to the relatlve motlon of unconnected sunspot pairs of opposite polarity, During the regressive stage of region NOAA 3885 a considerable rotation was observed In the main leader umbra.