Feed requirements were estimated from specific growth rates in standardized soft tissue dry weight (SGRDW’) and atomic O:N ratios for mussels fed seven rations of microalgae (5–735 μg C h?1 ind?1) at 7 and 14°C respectively. The mean oxygen consumption and ammonia‐N excretion rates were significantly higher at 14°C (0.29 μg O2 and 27.3 μg N ind?1 h1) compared with those at 7°C (0.16 μg O2 and 11.4 μg N ind?1 h?1) (P < 0.05), resulting in O:N ratios between 3 and 45 at 7°C and 7 and 28 at 14°C. Low O:N ratios indicate protein catabolism and an unfavourable condition, whereas high ratios indicate that carbohydrate is the primary energy source. The measured SGRDW’ suggests minimum feed requirements of ~240 and ~570 μg C ind?1 h?1 for weight maintenance at 7 and 14°C, with corresponding O:N ratios of 24 and 16, respectively, indicating a more stressed condition at 14°C. A 0.5% SGRDW’ day?1 was obtained by ~565 (O:N = 29) and ~680 (O:N = 23) μg C ind?1 h?1 at 7 and 14°C respectively. A positive and significantly higher SGRDW’, with the lowest feed ration at 7°C compared with a negative SGRDW’ at 14°C (P < 0.05), indicated that storage time can also possibly be prolonged at low temperatures if the mussels are not fed. 相似文献
According to studies, latent Toxoplasma gondii infection may affect several functions of the human brain. Here we search for the association between latent toxoplasmosis and cognitive performance. We tested 70 individuals for latent T. gondii infection. There were 26 Toxoplasma-infected subjects and 44 Toxoplasma-free subjects. Within these two groups we assessed cognitive performance using a set of standardized, widely recognized neuropsychological tests: Trail Making Test, Stroop Test, Verbal Fluency Test, Digit Span Test and N-back test. The relationship between chronic toxoplasmosis and cognitive performance was assessed, with adjustment for age and sex. Patients with latent toxoplasmosis performed worse on one neuropsychological test, N-back Test--percentage of correct answers (beta -8.08; 95% CI - 15.64 to -0.53; p < 0.05) compared to seronegative patients. However, after adjustment for age and sex, no statistically significant associations between latent toxoplasmosis and the scores on any cognitive tests were noticed. As statistically significant relationship was not observed, this study does not confirm that chronic latent T. gondii infection affects cognition. 相似文献
The crystal structure at 4.8 angstrom resolution of the reaction center-light harvesting 1 (RC-LH1) core complex from Rhodopseudomonas palustris shows the reaction center surrounded by an oval LH1 complex that consists of 15 pairs of transmembrane helical alpha- and beta-apoproteins and their coordinated bacteriochlorophylls. Complete closure of the RC by the LH1 is prevented by a single transmembrane helix, out of register with the array of inner LH1 alpha-apoproteins. This break, located next to the binding site in the reaction center for the secondary electron acceptor ubiquinone (UQB), may provide a portal through which UQB can transfer electrons to cytochrome b/c1. 相似文献
The objective was to verify the uniformity of single superphosphate distribution among seeder-fertilizer rows and its consequences on crops. The experiment was installed in the municipality of Tibagi—PR, involving the following crop rotation in the same area: black oat (Avena strigosa) in 2012, corn (Zea mays) in the 2012–13 season, wheat (Triticum aestivum) in 2013, soybeans (Glycine max) in the 2013–14 season, black oat in 2014 and corn closing the cycle in the 2014–15 season. The experimental design was used in randomized blocks, considering the number of rows of the seeder-fertilizer (ranging from 11 for corn to 27 for wheat) as treatments; with three replicates. During the experimental period, 250 kg ha?1 of single superphosphate were distributed per crop at sowing, with a mean deviation of up to 14% and variation in the fertilizer mass among the seeder-fertilizer rows in up to 52%. The variables evaluated were initial population and income components. It was concluded that it is not possible to correlate the variation of fertilizer distribution among rows of the seeder-fertilizer with the variables that presented significant differences in the crops through three agricultural seasons. This fact may be related to the alternation of the highest and lowest doses of simple superphosphate. Due to the succession of seeder-fertilizers used over the years to crops seeding, there was a compensation for the random variation of fertilizer among rows and crop spacings along the crop seasons.
Normative regulations on benzene in fuels and urban management strategies are expected to improve air quality. The present study deals with the application of self-organizing maps (SOMs) in order to explore the spatiotemporal variations of benzene, toluene, ethylbenzene, and xylene levels in an urban atmosphere. Temperature, wind speed, and concentration values of these four volatile organic compounds were measured after passive sampling at 21 different sampling sites located in the city of Trieste (Italy) in the framework of a multi-year long-term monitoring program. SOM helps in defining pollution patterns and changes in the urban context, showing clear improvements for what concerns benzene, toluene, ethylbenzene, and xylene concentrations in air for the 2001–2008 timeframe. 相似文献
This research introduces a new share design (L-share) that reduces the undesired random soil movement, providing a more controlled disturbance of the upper soil layer. Purpose: The aim of this study was to evaluate draught forces and soil movements when operating the new share. Materials and Methods: Experiments were conducted in a laboratory set-up using a soil bin with a fine loamy soil texture. The soil was compacted to a bulk density of 1500?kg?m?3, with a penetration index of 486?kPa and a mean water content of 10%. The cultivation depths were 30, 50 and 70?mm and the operation speeds were 0.84, 1.67 and 2.31?m?s?1. Cubes were used to measure soil movement by recording the displacement from their initial positions. The soil surface and furrow profile were measured by using a 2D laser range scanner. Results: The results showed that increasing operation speed and cultivation depths generally increased draught forces and soil movement. Changing the cultivation depth from 30 to 50?mm resulted in a 63% greater longitudinal force (Fx), and 71% greater Fx when increasing the cultivation depth from 50 to 70?mm. Conclusion: The study showed that the new L-share mounted on a modified spring tine only causes minor soil movement and thereby minimising the undesirable soil movement. 相似文献
The aim of the present work was to study the effect of humic preparation on the yielding capacity of winter wheat, the dynamics of mineral nutrients in the rhizosphere, and the activity of rhizosphere microbial community, as well as the protective properties of humate treatment under the stress caused by the application of a sulfonylurea herbicide.
Materials and methods
The humic preparation BIO-Don is prepared from vermicompost by alkaline extraction. The effect of humic preparation was estimated in a field experiment. The contents of the mobile ammonium and nitrate, exchangeable potassium, phosphorus, and humus were determined. Sampling and nutrient determination were performed in the tillering, booting, and grain maturing stages. Production experiments on the study of the combined effect of the humic preparation and the sunfonylurea pesticide Granstar Pro were performed in 2015 and 2017. The dynamics of mobile phosphorus in soil was studied. The abundance of culturable bacteria in the rhizosphere and bacterial species with different ecological strategies was determined. The dominant bacterial species were identified by MALDI-TOF mass spectrometry.
Results and discussion
The results of a small-plot experiment showed that at the tillering stage, the use of humic preparation has led to significantly higher supply of soil with mobile phosphorus. The winter wheat yield was 32.0 dt/ha in the control and 39.2 dt/ha with humic preparation or 22.5% gain in yield. The results of production experiment show that the application of sulfonylurea herbicide induced a chemical stress on winter wheat plants, but the use of humic preparation reduced this effect and increased the availability of phosphorus compounds. The treatment of plants with pesticides caused the general decrease in abundance of bacteria in the rhizosphere. The effect on quickly growing bacteria is more pronounced, while slowly growing bacteria and fungi are more resistant to this impact.
Conclusions
The application of humic preparation to winter wheat plantations allows to decrease the toxic effect of sulfonylurea herbicide, improve the supply of soil with mineral nutrients, and increase the crop yield. The favorable effects of humic preparation can be related to the active regulation of phosphorus mobilization by plants through the mechanism of root exudates due to the activation of root microbiota.
The study was carried out over a period of 1999–2003 in the Dupniański Stream catchment located in Silesian Beskid Mts. Region
(Southern Poland). Analysis of the chemical composition of bulk precipitation, throughfall, stemflow, surface flow, soil water
(horizontal + vertical and vertical penetration) and outflow water samples was performed. The complex data matrix with more
than 3,000 observations of water reaction, major anions (F−, Cl−, NO3−, SO42−) and cations (NH4+, Na+, K+, Ca2+, Mg2+, Fe2+, Mn2+ and Zn2+) were treated by regression modelling. The modelling approach took into account seasonal variability according to winter
and growing season, as well as chronosequence of spruce stands. The retention of considerable levels of contaminants by the
canopy, and their removal or washout from needles by rainfall caused changes in the concentration of anions and cations reaching
the soil surface compared to the concentrations in bulk precipitation. In the youngest stand, most elements except NH4+, SO42− and K+ were retained in the canopy, and even H+ ions were neutralized. In the older stands, most elements increased in net throughfall fluxes, and the acidity increased
strongly. Soil water was slightly correlated with throughfall, while outflow water showed no correlations with the above ground
water flows, and seemed to depend mostly of the bedrock. 相似文献
Laboratory experiments were done to determine the effect of geochemical composition of diatomaceous earth (DE) on insecticidal activity of DE against adults of the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae). Samples of DE were mined from DE-deposits in Slovenia, Greece, and Serbia. In addition, a commercially available DE formulation (SilicoSec®) was used in the tests and served as a positive control. The bioassays were carried out at temperatures 20, 25, and 30°C, relative humidity levels of 55 and 75%, and at application rates of 100, 300, 500, and 900 ppm. Adult mortality was recorded after 7, 14, and 21 days of exposure. Prior to bioassays with S. oryzae, the geochemical composition of all DEs that were used in the tests was determined by whole rock ICP geochemical analyses. Silica (in the form of SiO2 or opal-A) was the DE ingredient that was significantly correlated with efficacy in most of the bioassays. Some weak positive correlation was observed between S. oryzae mortality and MnO or CaO content. All significant correlations between mortality and Al2O3, Fe2O3, K2O, TiO2, Cr2O3, P2O5, and MgO content were negative, while correlation between Na2O content and mortality was generally not significant. 相似文献
Fusarium head blight (FHB), caused by the fungal plant pathogen Fusarium, is a fungal disease that occurs in wheat and can cause significant yield and grain quality losses. The present paper examines variation in the resistance of spring wheat lines derived from a cross between Zebra and Saar cultivars. Experiments covering 198 lines and parental cultivars were conducted in three years, in which inoculation with Fusarium culmorum was applied. Resistance levels were estimated by scoring disease symptoms on kernels. In spite of a similar reaction of parents to F. culmorum infection, significant differentiation between lines was found in all the analyzed traits. Seven molecular markers selected as linked to FHB resistance QTLs gave polymorphic products for Zebra and Saar: Xgwm566, Xgwm46, Xgwm389, Xgwm533, Xgwm156, Xwmc238, and Xgwm341. Markers Xgwm389 and Xgwm533 were associated with the rate of Fusarium-damaged kernels (FDK) as well as with kernel weight per spike and thousand kernel weight in control plants. Zebra allele of marker Xwmc238 increased kernel weight per spike and thousand kernel weight both in control and infected plants, whereas Zebra allele of marker Xgwm566 reduced the percentage of FDK and simultaneously reduced the thousand kernel weight in control and infected plants. 相似文献
