Dry matter, leaf area, leaf area ratio (LAR), specific leaf mass (SLM), and chlorophyll (Chi) a and b contents in different cultivars, lines and Fj hybrids of tomato plants (Lycorpersicon esculentum Mill.) were studied under constant in vitro conditions. Plant biomass and Chi content heterosis were observed in all breeding combinations regardless of genotypic features of initial forms. No differences in leaf area were found among cultivars, lines and Fj hybrids. High significant correlations were established among dry matter production, LAR and SLM values.
The paper deals with an experimental investigation of impacts of non-rotating spherical bodies on a flat, solid surface in water. The aim of the investigation was, using the PIV (Particle Image Velocimetry), method to analyze the velocity fields around the falling sphere which falls in an oblique direction. The experiments showed that the wake that forms behind the sphere is asymmetrical and that after the impact it continues its morion to the bottom, only along one side of the sphere, though. This non-symmetrical velocity field results in additional forces which push the sphere to the opposite direction than is the direction of the sphere motion just after the impact. and Obsahuje seznam literatury
C4 photosynthetic pathway and life form were determined for 159 species in 71 genera and 13 families in the grassland of North China. 45 % of the C4 species were found in Graminae, 19 % in each of Cyperaceae and Chenopodiaceae. More than 51 % of these C4 species were in therophyta and 36 % hemicryptophyta, while fewer species were in nanophanerophyta (9 %) or geophyta (5 %). The numbers of C4 species and their life forms were closely related with grassland deterioration and succession in North China. This indicated that the C4 species had greater capacity to tolerate environmental stress (e.g. drought and salinity) caused by animal grazing and cultivation.
The processing of ombrographic data from 29 meteorological stations of the Czech Hydrometeorological Institute (CHMI), according to the terms of the Universal Soil Loss Equation for calculating long term loss of soil through water erosion, erosion hazard rains and their occurrence have been selected, with their relative amount and erosiveness - R-Factors determined for each month and years. By comparing the value of the time division of the R-Factor in the area of the Czech Republic and in selected areas of the USA it has been demonstrated that this division may be applied in the conditions of the Czech Republic. For the Czech Republic it is recommended to use the average value R = 40 based on the original evaluation.