The effect of various environmental factors on net photosynthesis rates (P^) of the differentially depth distributed Mozambican seagrasses, Cymodocea serrulata (R.Br.) Aschers and Magnus (Zannich), and Thalassodendron ciliatum (Forsk.) den Hartog, was examined. At saturating irradiances the deeper water species, T. ciliatum, showed a maximum (as measured by short term O2 evolution) of 12.67 ± 3.33 mmol(02) kg-i(Chl) s ' with added 40 mM NaHCOj (0.89 mM dissolved CO2 at pH 8); the shallower species, C. serrulata, showed maximum rates of 21.67 ± 4.17 (10 mM NaHC03; 0.26 mM dissolved CO2). Saturating irradiances were similar for both species. PN estimated by the lacunal gas discharge technique was 16.00 ± 5.00 mmol(02) kg-'(Chl) s"’ for C. serrulata and 11.67 ±6.67 for T. ciliatum. Pn of both species was reduced by increased water depth, and the pattem of the effect of depth was similar.
Plants cultivated on acid soils that contain toxic levels of Al3+ usually produce low yields. A multi-factorial treatment of gypsum (G), boron (B), and limestone (Lm) was applied to such soil in order to determine the biochemical basis of the best management plan for ameliorating the soil acidity for sustainable growth of alfalfa. The alfalfa shoots were subjected to analysis for hexose, protein, nucleotide, and chlorophyll (Chl) contents, fructose 1,6-bisphosphatase (FBPase) activity, and the RNA synthetic activity of glutamate dehydrogenase (GDH). Hexose and protein contents of control alfalfa without B and G, but with Lm (672 g m-2) amendment were 0.87 and 38.30 g, respectively, per kg shoot. Increasing the G doses at fixed moderate doses of 0.15 and 0.30 g m-2 B decreased the FBPase activity by ∼53 and ∼31 %, respectively. However, increasing the B doses at higher fixed G (1 kg m-2= G1.0) increased the FBPase activity by ∼91 % thus indicating that G1 optimized the saccharide metabolism by neutralizing the soil acidity. In the absence of B, increasing the G doses also maximized the hexose and Chl contents, but minimized the nucleotide amount. In the absence of G, increasing the B doses maximized the RNA synthetic activity of GDH, but lowered the hexose and Chl contents as well as the FBPase activity without affecting the protein contents, thereby permitting the selection of B (0.45 g m-2) with Lm as the best amendment for the sustainable growth of alfalfa. Treatment with 0.45 g B and 0.5 kg G (= G0.5) induced the strongest B-Ca antagonism by maximizing the hexose and Chl contents but severely suppressing the FBPase activity and the RNA synthetic activity of GDH. Therefore, the coordinate optimization of saccharide metabolism through the G-dependent neutralization of soil acidity, and of RNA metabolism through the B-dependent detoxification of Al3+ are the biochemical options for the mitigation of the adverse effects of soil acidity for the optimization of sustainable alfalfa production. and G. O. Osuji ... [et al.].
This paper is concentrated on a reactive sensor - based omnidirectional motion mode in in-door robot surrounding. A high accuracy dead - reckogning and obstacle avoidance of the robot is acquired. The method supposes the use of odometer robot means. The model assumes that the wheel distance measurement errors are random zero means white noise. Algorithms developed will be implemented within a generic SW architecture and used on ‘OMR III‘ experimental robot. and Obsahuje seznam literatury
To rank variables affecting risk of human disease due to tick-borne encephalitis (TBE) virus in the Russian Far East, we compared annual changes in ( 1 ) frequency of human contact with vector ticks, (2) prevalence of infection in the tick population and (3) quantity of virus present infected ticks. Sites were sampled uniformly over a 4-year period in a forested region where Ixodes persulcatus serves as the principle vector. The questing density of ticks on vegetation remained relatively constant during the course of this study. The frequency of contacts of the local human population with ticks carrying different doses of the TBE virus was changeable. The rate of TBE infection of humans in the study site corresponded to that of human contacts with highly infected ticks. The density of highly infected ticks represents the principal parameter for determining potential epidemiological significance of a natural TBE focus.