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1.
Abstract

Genetic parameters were estimated for lactation average somatic cell score (SCS) and clinical mastitis (CM) for the first three lactations of multiparous Finnish Ayrshire cows. A multi-trait linear sire model was used for estimation of covariance components, and the efficiencies of single- versus multi-trait multi-lactation (MT) sire evaluations were compared. Heritability of SCS and CM in the first three lactations ranged from 0.11 to 0.13 and 0.02 to 0.03, respectively. Within lactation, genetic correlations between SCS and CM ranged from 0.68 to 0.72. Within both traits, across-lactation genetic correlations were lowest between 1 and 3, and highest between 2 and 3, with estimates ranging from 0.75 to 0.86 and from 0.81 to 0.98 for CM and SCS, respectively. Residual and phenotypic correlations were low and ranged from 0.09 to 0.13 and from 0.10 to 0.13, respectively. The absolute difference between genetic and residual correlations was from 0.5 to 0.6. Within-lactation genetic correlations between traits that are much less than unity suggest a multi-trait model for genetic evaluation of mastitis resistance. Comparison of model prediction performance between single-trait (ST) and MT models using a data splitting method showed that the MT model was more stable in predicting breeding values in future records of animals. Especially, for young sires and CM, the SD of EBVs from the MT model was 14 to 23% higher than the ST model, indicating more effective use of information in terms of revealing more genetic variation.  相似文献   
2.
The development of woodlots as an additional source of livelihood and as a land management option for small-scale farmers is a challenging issue in the cereal-based subsistence farming systems of north-western Ethiopia. There is a need to understand why and which factors determine the decisions of small-scale farmers to grow short-rotation woodlots on their land. Data used in this study were collected from a survey of 200 randomly selected households in the region. A Tobit regression model was used to determine predictor variables for farmers’ decisions to allocate land to planting Acacia decurrens (J.C. Wendl.) Willd. and at what density trees are planted on the respective plots. The most important motivations for planting A. decurrens were income, soil fertility management, and soil and water conservation. Having a male head of household, long distance to markets and plots being on marginal land, among other factors, increased the allocation of land to A. decurrens woodlots. Having a male head of household, access to credit and plots being on marginal land, among other factors, increased tree planting density. Age had a negative effect on both allocation of land to woodlots and tree density, whereas farm size had an inverted U-shaped relationship with both decisions. These results suggest that wider expansion of A. decurrens-based plantation systems could be achieved through improving extension, credit access and road infrastructure to connect small-scale farmers to markets and finance.  相似文献   
3.
The combination of runoff‐generating areas (saturated soils) and overland flow concentration in features such as drainage ditches makes sloping farmland vulnerable to soil erosion. The establishment of drainage ditches aims at draining the excess of water from the farmland, particularly in areas where soils are saturated in the rainy season. The hydrogeomorphic impacts on the farmland itself and on downstream areas need however also to be studied. Off site, downstream problems comprise higher peak discharges, leading to gully initiation, an increase in sediment load, and flooding problems. On‐site problems such as the development of the drainage ditches into (ephemeral) gullies are less documented, although they may be important, as illustrated in the Lake Tana Basin (Ethiopia). The similarities and interactions between ephemeral gully channels and drainage ditches have to be considered to better understand all effects of drainage. Drainage ditches are a potential source of conflict between farmers with different interests and power, as well as between upstream and downstream users. A case study on drainage ditches on sloping farmlands in the Lake Tana Basin showed that nine out of ten catchments had drainage densities by ditches ranging from 53 to 510 m ha−1. Drainage ditches were constructed with an average top width of 27 (±9) cm. A significant correlation was found between stone bund density (physical conservation structures) and ditch drainage density (R = −0·72), in line with the Ethiopian government's ban on drainage ditches in farmlands where stone bunds have been constructed. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
4.
Abstract

Two sets of field experiments under seedling transplanting and drill row seed planting methods were conducted side by side for two years during the main cropping seasons of 2017 and 2018 in Fogera Plain of northwest Ethiopia to study the effect of different sources, application methods and time of nitrogen fertilizer on growth and yield of rain-fed lowland rice. Three N sources of fertilizers (conventional Urea, Urea super-granule, and slow-release Urea) with six, one, and three application methods and times, respectively were laid out in a randomized complete block design (RCBD) in three replicates. These treatments and design were equally applied for two sets of experiments under both planting methods. Results revealed that soil-plant analysis development (SPAD) value, LAI, and biomass and grain yields of rain-fed lowland rice were highest with Urea supergranule N fertilizer sources followed by slow-release Urea and conventional Urea applications in both planting methods. Average grain yields of 3.7 and 3.8 tons ha?1 of rain-fed lowland rice were recorded with the application of Urea supergranule N source fertilizer under seedling transplanting and drill row seed planting methods, respectively. Hence, using Urea supergranule tablet is recommendable for getting better grain yield of rain-fed lowland rice without yield penalty in both planting methods.  相似文献   
5.
In developing countries such as Ethiopia, research to develop and promote soil and water conservation practices rarely addressed regional diversity. Using a water-balance approach in this study, we used runoff plots from three sites, each representing a different agro-ecological environment, e.g., high, mid and low in both elevation and rainfall, in the Upper Blue Nile Basin of Ethiopia to examine the runoff response and runoff conservation efficiency of a range of different soil and water conservation measures and their impacts on soil moisture. The plots at each site represented common land use types(cultivated vs. non-agricultural land use types) and slopes(gentle and steep). Seasonal runoff from control plots in the highlands ranged 214–560 versus 253–475 mm at midlands and 119–200 mm at lowlands. The three soil and water conservation techniques applied in cultivated land increased runoff conservation efficiency by 32% to 51%, depending on the site. At the moist subtropical site in a highland region, soil and water conservation increased soil moisture enough to potentially cause waterlogging, which was absent at the lowrainfall sites. Soil bunds combined with Vetiveria zizanioides grass in cultivated land and short trenches in grassland conserved the most runoff(51% and 55%, respectively). Runoff responses showed high spatial variation within and between land use types, causing high variation in soil and water conservation efficiency. Our results highlight the need to understand the role of the agro-ecological environment in the success of soil and water conservation measures to control runoff and hydrological dynamics. This understanding will support policy development to promote the adoption of suitable techniques that can be tested at other locations with similar soil, climatic, and topographic conditions.  相似文献   
6.
The efficiency of symbiotic dinitrogen (N2) fixation in Vicia faba L. in combination with 3 different Rhizobium leguminosarum strains was studied in a pot experiment during vegetative and reproductive growth. The objective of the experiments was to assess variability among Rhizobium strains inoculated on single legume species and determine possible reasons for observed variations. Dry matter formation, N2 fixation and the carbon (C) costs of N2 fixation were determined in comparison with nodule free plants grown with urea. Nodule number and the capacity of different respiratory chains in the nodules were also measured. The plants inoculated with the Rhizobium strain A 37 formed less dry matter and fixed less N compared to the other two Rhizobium strains (Vic 1 and A 150). This coincided with a lower number of nodules and higher C costs of N2 fixation. The C costs for N2 fixation were in all cases significantly lower during reproductive growth compared to vegetative growth. Neither the latter nor the differences in C expenditure for N2 fixation between the Rhizobium strains could be explained in terms of differences or shifts in the capacity of different respiratory chains in the nodules.  相似文献   
7.
Inferences about genetic and residual correlation estimates and sire evaluations involving a categorical trait with linear model are ambiguous and mostly based on data simulations. In this study, estimates of variance components and prediction of breeding values in a model with a categorical and a continuous trait were compared between threshold–linear (TLM) and linear–linear models (LLM) in analysis of large clinical mastitis (CM) field data. Data on CM, somatic cell score (SCS), 305-day milk (MY), protein (PY) and fat yield (FY) from first-lactation Finnish Ayrshire cows were used. Four bivariate analyses were made using a TLM in Bayesian analysis. Each analysis fitted CM and one continuous trait at a time. Corresponding bivariate analyses were made using a Gaussian linear model. Estimates of heritabilities for CM were 0.06 and 0.02 from TLM and LLM, respectively whilst heritability estimates of the continuous traits were similar from both models. Genetic correlations between CM–SCS, CM–MY, CM–PY, and CM–FY from TLM and LLM were 0.63 and 0.63; 0.36 and 0.36; 0.32 and 0.32; 0.30 and 0.29, respectively. Estimates of residual correlations were 0.11 and 0.06; − 0.04 and − 0.02; − 0.03 and − 0.02; − 0.05 and − 0.03 between CM–SCS, CM–MY, CM–PY, and CM–FY, respectively. Comparison between the models indicates similar estimates of genetic correlations with no underestimation with the linear model analysis. In CM evaluation, the comparison of model's predictive ability showed greater improvements in accuracy with the bivariate than with the univariate models. There was, however no clear advantage of univariate threshold model over univariate linear model, except for less accuracy sires.  相似文献   
8.
Abstract

Traditional short-term diversification of annual crops for the purpose of improving soil fertility and food security is a common practice in Ethiopia. However, the best cropping systems have not been selected yet though field research. Experiments were conducted for two years with an objective of establishing sustained finger millet based short term cropping sequence in two major finger millet producing areas of Ethiopia. The experiments were laid out in a split-plot arrangement with six precursor crops (haricot bean, maize, sweet lupine, niger seed, wheat, and teff) as a main plot factor, where determined residues were retained in the main plot after harvesting and two nitrogen fertilizer levels (30 and 60?kg ha?1) applied for finger millet as sub-plots with three replications. Soil analysis result examined immediately after finger millet harvest showed a significant effect of precursor crops and nitrogen fertilizer rates on soil properties. Planting finger millet following lupine increased the soil organic carbon, total nitrogen and cation exchange capacity by 17.37%, 65.50%, 26.15%, respectively, over planting finger millet following teff. Use of different amount of nitrogen fertilizer likely contributed to observed differences in residual soil nutrients. Accordingly, finger millet following lupine with the addition of 60?kg ha?1 nitrogen fertilizer gave significantly higher finger millet grain yield (3.24 tone ha?1) and relative production (22.37%) and economic (40.7%) efficiency. This system with their high sustainability and multiple benefits can be readily accepted by the farming community.  相似文献   
9.
The present study aimed at the assessment of carbon (C) costs for nitrate reduction by measuring the additional CO2 amounts released from roots of nitrate‐fed plants in comparison with urea‐fed plants. Only roots were suitable for these determinations, because nitrate reduction in illuminated shoots is fed nearly exclusively by reducing equivalents coming directly from photosynthetic processes. Therefore, in a first experiment, the sites of nitrate reduction were determined in nodule‐free broad bean (Vicia faba L.) and pea (Pisum sativum L.) plants grown in pots filled with quartz sand and supplied with KNO3. The extent of nitrate reduction in the various plant organs was determined by measuring in vitro nitrate reductase activity and in situ 15NO reduction. Only between 9% and 16% of nitrate were reduced in roots of German pea cultivars, whilst 52% to 65% were reduced in broad bean roots. Therefore, C costs of the process could be determined only in broad bean, using an additional pot experiment. The C costs amounted to about 4.76 mol C (mol N)–1 or 4 mg C (mg N)–1, similar to those measured earlier for N2 fixation. The high proportion of nitrate reduction in shoots of pea plants implies that only very little C is required for this nitrate fraction. This can explain the better root growth of nitrate‐nourished pea plants in comparison with N2‐fixing organisms, which need C compounds for N2 reduction in roots. Moreover, a different availability of photosynthates in roots of plant genotypes could explain physiologically the occurrence of “shoot and root reducers” in nature.  相似文献   
10.
Phosphate sorption was studied in samples (0 - 20 cm depth) of five soils from Egypt (pH 7.4 - 8.7), four soils from Ethiopia (pH 3.9 - 5.3) and six soils from Germany (pH 3.3 - 7.2). Sorption parameters were calculated according to Pagel and Van Huay (1976) and according to Langmuir (Syers et al., 1973). Phosphate sorption parameters and oxalate extractable Fe and Al (Feox, Alox) were related to the phosphate uptake by young rye plants in Neubauer pot experiments. P sorption parameter after Pagel and Van Huay (A) correlated significantly positively with the Feox and Alox content in acid (r = 0.73) as well as in calcareous soils (r = 0.89) if the whole equilibrium concentration range (0 - 14 mg P/L) was considered. The relations calculated after Langmuir (B) were similar. P uptake by rye in acid soils was negatively correlated with the affinity constant n (r = ?0.76, (A)). In calcareous soils, a negative correlation between P uptake and affinity constant was calculated in the lower P equilibrium range (0 - 2.8 mg P/L) only for (B). Thus, P uptake decreased with increasing strength of P bonding to soil. From these results it is concluded that phosphate sorbed to Fe/Al oxides is an important P source for plants in acid and calcareous soils.  相似文献   
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