排序方式： 共有22条查询结果，搜索用时 31 毫秒
1.
Summary The effects on quantitative characters of the ml-o5 allele has been investigated by means of doubled haploid lines produced by the Hordeum bulbosum method. In one series of experiments the genetic background in each cross was found significantly to modify the negative pleiotropic effects. Doubled haploids were also produced from a F1 cross and tested in the field during two years, one with strong and one with weak mildew infections. In the first year only an insignificant reduction in grain yield was detected in the mlo lines, in the second it was significantly reduced with 5.9%. Thousand grain weights were, however, higher in the resistant lines. In both series of experiments the possibility to extract very high yielding mlo genotypes was demonstrated. The nature of the genetic background effect is discussed. 相似文献
2.
Methane uptake in Swedish forest soil in relation to liming and extra N-deposition 总被引：11，自引：0，他引：11
Methane uptake to soil was examined in individual chambers at three small forest catchments with different treatments, Control,
Limed and Nitrex sites, where N-deposition was experimentally increased. The catchments consisted of both well-drained forest
and wet sphagnum areas, and showed uptake of CH4 from the ambient air. The lowest CH4 uptakes were observed in the wet areas, where the different treatments did not influence the uptake rate. In the well-drained
areas the CH4 uptakes were 1.6, 1.4 and 0.6 kg ha–1 year–1 for the Limed, Control and Nitrex sites, respectively. The uptake of methane at the well-drained Nitrex site was statistically
smaller than at the other well-drained catchments. Both acidification and increase in nitrogen in the soil, caused by the
air-borne deposition, are the probable cause for the reduction in the methane uptake potential. Uptake of methane was correlated
to soil water content or temperature for individual chambers at the well-drained sites. The uptake rate of methane in soil
cores was largest in the 0- to 10-cm upper soil layer. The concentration of CH4 in the soil was lower than the atmospheric concentration up to 30 cm depth, where methane production occurred. Besides acting
as a sink for atmospheric methane, the oxidizing process in soil prevents the release of produced methane from deeper soil
layers reaching the atmosphere.
Received: 27 September 1996 相似文献
3.
Å. H. Garseth C. Fritsvold M. Opheim E. Skjerve E. Biering 《Journal of fish diseases》2013,36(5):483-493
This is the first comprehensive study on the occurrence and distribution of piscine reovirus (PRV) in Atlantic salmon, Salmo salar L., caught in Norwegian rivers. PRV is a newly discovered reovirus associated with heart and skeletal muscle inflammation (HSMI), a serious and commercially important disease affecting farmed Atlantic salmon in Norway. A cross‐sectional survey based on real‐time RT‐PCR screening of head kidney samples from wild, cultivated and escaped farmed Atlantic salmon caught from 2007 to 2009 in Norwegian rivers has been conducted. In addition, anadromous trout (sea‐trout), Salmo trutta L., caught from 2007 to 2010, and anadromous Arctic char, Salvelinus alpinus (L.), caught from 2007 to 2009, were tested. PRV was detected in Atlantic salmon from all counties included in the study and in 31 of 36 examined rivers. PRV was also detected in sea‐trout but not in anadromous Arctic char. In this study, the mean proportion of PRV positives was 13.4% in wild Atlantic salmon, 24.0% in salmon released for stock enhancement purposes and 55.2% in escaped farmed salmon. Histopathological examination of hearts from 21 PRV‐positive wild and one cultivated salmon (Ct values ranging from 17.0 to 39.8) revealed no HSMI‐related lesions. Thus, it seems that PRV is widespread in Atlantic salmon returning to Norwegian rivers, and that the virus can be present in high titres without causing lesions traditionally associated with HSMI. 相似文献
4.
Liv Å. Espeby Håkan Fogelfors Sara Sjödal 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(3):211-219
Continuous increase in glyphosate use in Sweden has caused concern about resistance development, not least in connection with the possible introduction of crops resistant to glyphosate. In Sweden, the main weed targeted by glyphosate is Elymus repens (L.) Gould. We sampled 69 clones of E. repens to assess the magnitude and geographical distribution of variation in susceptibility to glyphosate. Clones originated from four habitat types: intensively and extensively used arable lands, field vicinities and other habitats, including natural vegetation. Susceptibility varied greatly among clones with GR50 (50% of untreated growth reduction) spanning over at least one order of magnitude, 17–278 active ingredient ha?1 in a pot experiment setting. There was a strong covariance between geographic and genetic distance, but there was no evidence of geographic or genetic differentiation in GR50. Nor did GR50 vary consistently between habitat types. We conclude that no indication of past selection was found towards the resistance to glyphosate in E. repens clones in Sweden. The great variability in susceptibility suggests that there might be a potential for such selection. 相似文献
5.
Sz. Márkus E.A. Mäntysaari I. Strandén J‐Å. Eriksson M.H. Lidauer 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2014,131(3):237-246
Two heterogeneous variance adjustment methods and two variance models were compared in a simulation study. The method used for heterogeneous variance adjustment in the Nordic test‐day model, which is a multiplicative method based on Meuwissen (J. Dairy Sci., 79, 1996, 310), was compared with a restricted multiplicative method where the fixed effects were not scaled. Both methods were tested with two different variance models, one with a herd‐year and the other with a herd‐year‐month random effect. The simulation study was built on two field data sets from Swedish Red dairy cattle herds. For both data sets, 200 herds with test‐day observations over a 12‐year period were sampled. For one data set, herds were sampled randomly, while for the other, each herd was required to have at least 10 first‐calving cows per year. The simulations supported the applicability of both methods and models, but the multiplicative mixed model was more sensitive in the case of small strata sizes. Estimation of variance components for the variance models resulted in different parameter estimates, depending on the applied heterogeneous variance adjustment method and variance model combination. Our analyses showed that the assumption of a first‐order autoregressive correlation structure between random‐effect levels is reasonable when within‐herd heterogeneity is modelled by year classes, but less appropriate for within‐herd heterogeneity by month classes. Of the studied alternatives, the multiplicative method and a variance model with a random herd‐year effect were found most suitable for the Nordic test‐day model for dairy cattle evaluation. 相似文献
6.
A. Brabrand 《Ecology of Freshwater Fish》1995,4(2):70-76
Cohorts of perch larvae, hatched within 24 h, developed into a bimodal body size distribution as early as 6 days after commencement of external food uptake. At this development stage, intra-cohort cannibalism occurred among larval perch individuals of larval stage V (body size: 10.5±0.26 mm, 95% c. l.) on smaller siblings. In experimental trials the consumption rate (C: no. of prey/predator·hour) increased exponentially with size of predatory perch (L: mm) and at 21°C was expressed by the relationship log C=3.406·log L-3.848 (n=10, r2=0.98, P<0.001). For predatory perch in larval stage V, consumption rate was reduced when Daphnia pulex were added, while not in later stages. Perch larvae experimentally forced to live as true piscivores without additional food items developed from stage V to stage IX (15.8±1.34 mm) within the same time as those fed on Daphnia alone, but with increased mortality. 相似文献
7.
Hydropower operations in groundwater‐influenced rivers: implications for Atlantic salmon,Salmo salar,early life stage development and survival 
下载免费PDF全文
下载免费PDF全文 R. Casas‐Mulet K. Alfredsen Å. Brabrand S. J. Saltveit 《Fisheries Management and Ecology》2016,23(2):144-151
During their early life stages (egg maturation, hatching, alevin development), between late autumn and early spring, young Atlantic salmon are exposed to surface‐groundwater interactions in the hyporheic zone and may depend on influx of subsurface water during periods of regulated low discharge for survival. Two studies, one in a seasonally regulated river and one in a river exposed to hydropeaking, displayed unexpectedly high survival of eggs in surface de‐watered areas because of the influx of oxygen‐rich subsurface water. Field observations of newly hatched alevins in these two rivers showed them to be more sensitive (i.e. suffered higher mortality from) to surface de‐watering than were eggs. Exposure to dry conditions in drawdown areas was highlighted as the main cause for alevin mortality. Therefore, shorter periods of surface de‐watering in the river with hydropeaking resulted in higher alevin survival than the seasonally regulated river when still permanently drained after egg hatching. Greater consideration should be given to all early life‐history stages when implementing discharge release strategies, and the extent of groundwater influence and the potential for flexible hydropower operations should be taken into account. 相似文献
8.
An investigation was made of the potential for attaining high daily live weight (LW) gain, high feeding efficiency and carcass quality in Norwegian Red (NRF) bulls fed grass silage harvested at early stages of maturity, supplemented with minimal amounts of concentrates. Roundbale silage was produced from timothy‐dominated swards harvested at three stages of maturity: stages 1 and 2 were dominated by tillers in stem elongation with two and three visible nodes, respectively, and stage 3 by tillers at early heading, with visible heads, but without head stems. Crops were wilted rapidly and a formic acid‐based additive applied. All silages were preserved with restricted fermentation. Silage DOMD values were 0·747, 0·708 and 0·647 for harvesting time (H) 1, 2 and 3 respectively. Silages were fed ad libitum as sole feed, or supplemented with 2–4 kg concentrate at increasing LW, to six bulls per treatment from age 7 months (288 kg) to slaughter at 575 kg. Daily LW gain for bulls fed unsupplemented silage was 1423, 1262 and 936 g, respectively, for H1, H2 and H3, and 1570, 1567 and 1357 g for supplemented bulls. For concentrate‐supplemented bulls, higher energy intake increased proportions of carcass fat more for H1 (0·163) than for H2 (0·134) but the same amount of energy was retained in the carcass per MJ net energy growth intake for these two groups. It is concluded that, apart from milk and concentrate fed to calves during the first months, an intensive beef production with NRF bulls finished before 15 months of age may be based entirely on local grass resources. 相似文献
9.
Summary Possible negative effects of tissue culture on qualitative and quantitative characters have been investigated in three crosses of spring barley, using doubled haploid lines produced by anther culture (AC, with maltose as a carbon source) or the Hordeum bulbosum-method (HB). In one cross inbred lines produced by single seed descent (SSD) have also been included. Quantitative characters were investigated in a 2-year field experiment at one location. The results show that although the methods in the majority of cases gave similar results, the genotypic arrays produced were not identical. Different markers deviated in the various cross/method combinations. The ranking of methods as well as the frequencies of lines transgressive for grain yield differed between crosses. Thus no consistently negative impact of anther culture in barley has been found, and, although not identical, the various methods may be considered equivalent.Abbreviations AC
Anther Culture method
- SSD
Single Seed Descent method
- HB
Hordeum bulbosum method 相似文献
10.
Gastric evacuation rate in brown trout (Salmo trutta L.) was studied in water qualities characteristic of non-acidified and acidified waters. The level of plasma chloride was reduced and hematocrit increased in the group exposed to acid water. The gastric evacuation rate was described by an exponential function. Instantaneous rates of gastric evacuation were not significantly different between the two groups. In both of the groups the rates were lower than observed in corresponding studies of brown trout. This was most likely caused by handling stress during the experiment. 相似文献