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171.
Since natural sturgeon populations have drastically declined, aquaculture of these valuable fish is important to meet the ever‐increasing demand for meat and caviar, thereby reducing the pressure on natural sturgeon resources. There are two directions in sturgeon aquaculture: controlled propagation for release and commercial farming. The controlled propagation supports the conservation of natural fish populations, while the commercial cultivation of sturgeons supplies the needs of the consumer market with the delicacy production of caviar (mainly). This review deals with the current status of the controlled propagation and stocking in the Volga‐Caspian basin and the commercial farming of sturgeons in Russia. The article also investigates the management of farmed broodstocks of sturgeons, which are used for obtaining seedlings and caviar. It is for sure that the active and continuous development of the two directions of sturgeon aquaculture will allow preserving these unique ancient fish on our planet until natural populations can be re‐established by self‐sustaining populations.  相似文献   
172.
This prospective study was designed to investigate the effects of maternal temperament on uterine blood flow, fetal heart rate, gestational length, and fetal birth weight in a goat experimental model. Based on the arena test, behavioral testing related to fear-eliciting stimulus, goats were divided into nervous (n = 13) and calm (n = 11) groups. After mating, the perfusion of maternal uterine arteries (UTAs) and its related Doppler parameters, blood flow volume (BFV), time-averaged mean velocity (TAMEANV), acceleration (Acce), and resistance impedance (S/D), were evaluated biweekly from week two until the end of pregnancy. Fetal heart rate (FHR) was investigated during the pregnancy in addition to the gestation length (GL) and fetal birth weight (FBW). The UTA-BFV and TAMEANV, as well as Acce and S/D, were influenced by maternal temperament (p < .05). The FHR showed no significant changes between experimental animals of different temperaments (p = .81). Both GL and FBW were increased in calm rather than nervous goats (p < .05). These results indicated that the maternal nervous (temperament) have negative impacts on uterine artery Doppler indices, fetal growth, and gestational length in a goat experimental model.  相似文献   
173.
Salinity is a widespread soil problem limiting productivity of oilseed crops worldwide. Reduction in growth generally associated with decline in photosynthesis. Accumulation of osmo‐protectants such as glycinebetaine (GB) permits the plant to cope with salt stress. This study was aimed to understand the mechanism by which exogenous GB application improves photosynthetic capacity and salt tolerance in two diverse lines of canola differing in salt tolerance using chlorophyll fluorescence technique. Glycinebetaine was applied as foliarly or through rooting medium to two canola lines Dunkeld and Cyclone that were grown under non‐saline or saline conditions. Root‐applied GB caused adverse effects whereas foliar application of GB was effective in improving growth of canola cultivars. However, the response of salt‐tolerant cultivar Dunkeld was stronger than that of salt sensitive Cyclone. Foliar application of GB improved accumulation of proline and plant water status. Application of GB enhanced the photosynthetic CO2 fixation, stomatal conductance (gs) and water‐use efficiency. The tolerant lines Dunkeld had more responsive to GB application. Chlorophyll fluorescence measurements (Fo, Fm, Fv, Fo/Fm, Fv/Fo and Fv/Fm ratios) revealed that salt stress reduced energy trapping efficiency by damaging oxygen evolving complex, over reduction of QA resulting in occurrence of chronic photoinhibition. However, exogenous GB protected the oxygen evolving centre of PSII and maintains activity of PSII. Although root‐applied GB adversely affected the growth of canola plants, it did not have any adverse effect on PSII photochemistry. Moreover, fluorescence parameters could provide a rapid means for determining salt tolerance in canola and could be a rapid and sensitive test to identify genotypes highly tolerant to salt stress.  相似文献   
174.
The aims of the present study were to determine uterine, vaginal and placental blood flows by Doppler ultrasound cross-buffalo gestation and to evaluate the relationships among reproductive Doppler parameters and serum metabolic parameters as well as oxidative stress. Uterine (UA) and vaginal (VA) arteries were scanned every month, and placentome was scanned from month 4 till 8 in gestation. Time-averaged maximum velocity (TAMV), pulsatility index (PI), resistance index (RI), systolic/diastolic ratio (SD) and arterial diameter (AD) were used for accessing UA and VA hemodynamics. Time-averaged maximum velocity positively correlated with and AD, and both negatively correlated with their PI, RI and SD in UA and VA. TAMV and AD increased constantly in pregnancy, with maximum increase in months 4 and 9. Pulsatility index, RI and AD of UA decreased between months 4 and 9, while PI, RI and AD of VA decreased between months 5 and 9 and then increased in month 10 in pregnancy. Time-averaged maximum velocity of placentome blood flow increased exponentially from months 4 to 8, but decreased at the last two months in pregnancy. Serum lipids were significantly higher in the first month compared to all other months, while glucose was significantly lower in months 9 and 10. Malondialdehyde increased from month 3 till term, but peaked in month 5 and 10. Glutathione and catalase were highest in the first month and remained after. Time-averaged maximum velocity and AD for both UA and VA negatively correlated with serum lipids, glucose, catalase and glutathione, while positively correlated with malondialdehyde and total protein. Thus, increases in uterine blood flow (UtBF), vaginal blood flow (VaBF) and placental blood flow (PaBF) are associated with increased metabolism and oxidative stress in buffalo pregnancy.  相似文献   
175.
An investigation was carried out on the extractability of heavy metals (HM) from livestock manure during composting and their uptake by spinach (Spinacia oleracea L.) from compost-amended soil. Significant temporal changes were recorded for elements during composting of manure. Higher concentrations of metals were observed during the early stages of composting. Conversely, later stages of composting produced higher amounts of calcium (Ca), magnesium (Mg) and sodium (Na) in the water extract. Total carbon (C) in the samples was inversely related to the length of composting. The application of composted manure increased spinach growth as compared to the fresh manure. Concentrations of HM in spinach varied in the order iron (Fe) > zinc (Zn) > manganese (Mn) > cadmium (Cd) > lead (Pb) > copper (Cu) and their release from post-harvest soil was identical to that in manure samples. The low extractability of HM may suggest that the use of composted manures would lessen environmental pollution problem in the fields.  相似文献   
176.
Azam  F.  Ashraf  M.  Lodhi  Asma  Sajjad  M. I. 《Biology and Fertility of Soils》1990,10(2):134-138
Summary A pot experiment was conducted to study the N availability to wheat and the loss of 15N-labelled fertilizer N as affected by the rate of rice-straw applied. The availability of soil N was also studied. The straw was incorporated in the soil 2 or 4 weeks before a sowing of wheat and allowed to decompose at a moisture content of 60% or 200% of the water-holding capacity. The wheat plants were harvested at maturity and the roots, straw, and grains were analysed for total N and 15N. The soil was analysed for total N and 15N after the harvest to determine the recovery of fertilizer N in the soil-plant system and assess its loss. The dry matter and N yields of wheat were significantly retarded in the soil amended with rice straw. The availability of soil N to wheat was significantly reduced due to the straw application, particularly at high moisture levels during pre-incubation, and was assumed to cause a reduction in the dry matter and N yields of wheat. A significant correlation (r=0.89) was observed between the uptake of soil N and the dry matter yield of wheat with different treatments. In unamended soil 31.44% of the fertilizer N was taken up by the wheat plants while 41.08% of fertilizer N was lost. The plant recovery of fertilizer N from the amended soil averaged 30.78% and the losses averaged 45.55%  相似文献   
177.
This study investigated the effects of arbuscular mycorrhizal (AM) colonisation by Glomus clarum on growth and fruit yield of pepper (Capsicum annum cv. 11B 14) grown at high salinity. The experiment was conducted in pots containing a mixture of perlite and sand (1:1, v/v) under glasshouse conditions. Treatments were: (1) no added NaCl without arbuscular mycorrhizae (NS-AM), (2) no added NaCl with arbuscular mycorrhizae (NS + AM), (3) added 50 mM NaCl without arbuscular mycorrhizae (S1-AM) and (4) added 100 mM NaCl without arbuscular mycorrhizae (S2-AM), (5) added 50 mM NaCl with arbuscular mycorrhizae (S1 + AM) and (4) added 100 mM NaCl with arbuscular mycorrhizae (S2 + AM). The NaCl treatments reduced pepper shoot and root dry matter, and fruit yield compared with the non-saline treatments. The concentrations of N, P and K, in the leaves were significantly reduced by salinity stress, however, mycorrhizal colonisation of the salt-stressed plants restored leaf nutrient concentrations to the levels in non-stressed plants in most cases. AM inoculation improved pepper growth under salt or saltless conditions and reduced cell membrane leakage.  相似文献   
178.
The present study was conducted to evaluate the effect of dietary ginseng herb (Ginsana® G115) supplementation on growth performance, feed utilization, and hematological indices of Nile tilapia, Oreochromis niloticus (L.), fingerlings. A total of 378 Nile tilapia fingerlings with an average body weight of 24.4 ± 0.2 g were divided in the six experimental treatments (three replicates each). The experiment was conducted for 17 wk. Six isonitrogenous, 27.2% digestible protein and isocaloric, 12.3 MJ/kg digestible energy experimental diets were formulated. The control diet had no Ginsana G115 added. Diets 2–6 each contained Ginsana G115 at levels of 50, 100, 150, 200, and 250 mg/kg, respectively. Growth performance and feed utilization efficiency of Nile tilapia were significantly (P ≤ 0.05) higher in all treatments receiving Ginsana G115‐supplemented diets than the control diet. Red blood cells counts, hematocrit, and hemoglobin significantly (P ≤ 0.05) increased with increasing dietary Ginsana G115 levels compared to those of the control diet. The same trend was observed for total plasma protein and total plasma globulin levels. The results of present study suggested that Nile tilapia fingerlings fed diets containing at least 200 mg/kg Ginsana G115 for 17 wk had enhanced growth performance, diet utilization efficiency, and hematological indices.  相似文献   
179.
Influence of sudden and gradual drought stress (DS) and foliar‐applied glycinebetaine (GB) on growth, water relations, osmolyte accumulation and antioxidant defence system were investigated in the plants of two maize (Zea mays L.) cultivars, that is, drought‐tolerant Shaandan 9 (S9) and drought‐sensitive Shaandan 911 (S911). Sudden DS caused less accumulation of GB and free proline, but a more accumulation of malondialdehyde (MDA), which resulted in a greater reduction in leaf relative water content (RWC) and dry matter (DM) in both cultivars compared with the gradual DS. Exogenous GB application caused a rise in DM, RWC, contents of GB and free proline as well as the activities of SOD, CAT and POD along with a decline in MDA content to various extent in both cultivars under both types of DS. A more pronounced effectiveness of GB application was observed in S911 than that in S9 under the same type of DS. It seemed that the more serious damage of DS was on maize plants, and the better positive role of GB was observed in terms of mitigating the adverse effects of DS. From this study, it was possible to propose that hardening for drought resistance by gradual DS treatment and GB application are effective to make plants robust to thrive under water‐deficit conditions.  相似文献   
180.
The balance of strength between the flange and web parts of veneer strand flanged I-beam was investigated by the following methods: (1) use of different web material types, such as plywood, oriented strand board (OSB), particleboard (PB), and medium density fiberboard (MDF), that have different strength properties; and (2) fabrication of I-beams with low-density flanges using low-density strands with PB web material. Replacing PB or MDF with plywood showed slight significant improvement in the modulus of rupture but not in the modulus of elasticity of the entire I-beam. However, PB and MDF showed competent performance in comparison with OSB, thus strengthening the promising future of the use of PB or MDF as web material to fabricate I-beams. Hot-pressing conditions used for I-beam production exerted slightly adverse effects on the bending properties of PB, but not on MDF, OSB, and plywood web materials. The flange density of 0.60 g/cm3 was considered to be the lower limit that provides I-beams with balanced mechanical properties and dimensional stability.  相似文献   
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