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Andargachew Gedebo Maigull Appelgren Asmund Bjornstad Admasu Tsegaye 《Genetic Resources and Crop Evolution》2007,54(7):1429-1436
For the first time we report that diverse types of Arisaema schimperianum Schott locally called amochi, are grown and managed as an off-season food crop in Southern Ethiopia. Participatory Rural
Appraisal (PRA) and formal survey studies on 204 households were conducted over two consecutive years (2003–2004) in Chencha
and Dita sub zones of Southern Ethiopia, to identify indigenous production methods and farm based biodiversity of amochi.
Amochi is propagated from seed tubers and tuber parts left in the soil from the preceding harvest and grow during the dry
season, February to June. Average share of proportion in the annual household consumption from amochi tubers was 9% and 4%
for Chencha and Dita respectively. Uncooked amochi is irritating in contact to skin and mouth. Fifteen amochi types were identified
in Dita and 12 in Chencha. They differ in the level of irritation, maturity and yield. Rich farmers with large family size
as a working force, large farm size to support larger number of livestock that is source of farmyard manure, have farms with
larger diversity of amochi than their poor counterparts, suggesting that its diversity is influenced by house hold characteristics
and favoured under relatively fertile soil conditions. In both sub zones women had better experience in identifying amochi
types than men. Further study is needed to identify chemical contents; and genetic variation using morphologic and molecular
traits, in order to develop a strategy to assess and utilise the existing genetic diversity. 相似文献
2.
Barley is one of the most important cereal crops grown for the livelihoods of the poor farmers of Tigray region in northern
Ethiopia. As many low input and marginal environments it has benefited less from the yield increases achieved by modern breeding.
This has been largely attributed due to genotype × environment intraction (GEI). To investigate the causes of GEI, ten barley
varieties including local checks (two farmers developed varieties, four modern varieties and three rare local varieties) were
tested over 21 environments. Participatory methods were applied to sample an adequate number of environments spanning the
regional diversity. The yielding ability and stability of the varieties was graphically depicted by GGE and PLSR biplot. There
were two major groups of environments, the central and northern highlands, the latter with less rainfall and poorer soils.
Rainfall per month and total nitrogen level were the environmental variables that differentiated these two groups. In Tigray,
rainfall in June and July were negatively correlated with yield, reflecting waterlogging problems. The different varieties
were either specifically or widely adapted across the two environments. The variety ‘Himblil’, originating in Tigray, was
the highest yielding and also most stable in the region of origin. However, it was inferior to improved varieties (Shege and
Dimtu) at high yield levels. The association of earliness with grain yield indicates that the trait can be effectively manipulated
within the existing materials. We recommend breeding for drought/water logging resistance based on selection in the target
environment as the best strategy to provide stable and high yielding varieties for Tigray. 相似文献
3.
Frank Rig��t Mikkel P. Tamstorf Martin M. Larsen Jens S?ndergaard Gert Asmund Julie Maria Falk Charlotte Sigsgaard 《Water, air, and soil pollution》2011,222(1-4):233-242
In a warming climate, mercury (Hg) pathways in the Arctic can be expected to be affected. The Hg transport from the high arctic Zackenberg River Basin was assessed in 2009 in order to describe and estimate the mercury transported from land to the marine environment. A total of 95 water samples were acquired and filtered (0.4 ??m pore size), and Hg concentrations were determined in both the filtered water and in the sediment. A range of other elements were also measured in the water samples. Hg concentrations in the filtered water were in general highest in the beginning of the season when the water came mainly from melted snow. THg concentrations in the sediment were in general relatively constant or slightly decreasing until mid-August, where after the concentrations increased. A principal component analysis separated the samples into spring, summer and autumn samples indicating seasonal characteristics of the patterns of element concentrations. The total amount of Hg in the sediment transported was estimated to 2.6 kg. Approximately 60% of the sediment-transported Hg occurred during a 24-h flood in the beginning of August caused by a glacial lake outburst flood. The total amount of transported dissolved Hg was estimated to 46 g, and 13% of this transport occurred during the 24-h flood. If it is assumed that the Hg transport by Zackenberg River is representative for the general glacial rivers in East Greenland, the total Hg transport into the North Atlantic from Greenland alone is approximately 4.6 tons year?1 with an estimated annual freshwater discharge of ??440 km3. 相似文献
4.
Trends in population and labor force growth in nonmetropolitan areas of the United States during the 1970s are analyzed. The authors investigate the relationships among migration behavior, urban accessibility, and externalities such as congestion that are associated with urban residence. "A model of the migration decision [is examined] that incorporates in an explicit fashion this proximity-centrality relationship. Estimates of the model are also discussed, with specific attention given to the relationship under question. In addition, the age selectivity of the relationship [is] examined. Insights on the nonmetropolitan reversal drawn from the model estimates are discussed in a third section, followed by concluding remarks." 相似文献
5.
B. Elberling H. Breuning-madsen H. Hinge & G. Asmund 《European Journal of Soil Science》2010,61(1):74-83
For evaluating present concentrations of heavy metals in soils, it is important to be able to determine natural or background soil concentrations. Here, we compare the content of 7 m HNO3 -extractable and 0.2 m Na-EDTA-extractable fractions of cadmium (Cd), zinc (Zn), lead (Pb) and copper (Cu) in present day cultivated A horizons (Ap) under different land uses and 19 buried A horizons (Apb) that have been covered by 3300-year-old burial mounds. The buried A horizons represent a unique opportunity to evaluate background concentrations of heavy metals in top soil. Variations in background concentrations were mainly related to clay content. Using the grain size distribution of present-day topsoils (cultivated and forest/natural A horizons), the background concentrations were calculated and subtracted from observed concentrations prior to an evaluation of soil-type- and land-use-specific metal accumulation. All cultivated soils were significantly enriched with respect to Cd, Pb, Zn and Cu over the last 3300 years and all forest soils were enriched with Pb. The study highlights the importance of using appropriate reference material for assessing present-day metal concentrations and stocks. 相似文献
6.
Amplified fragment length polymorphism (AFLP) and random amplified polymorphic DNA (RAPD) analyses were performed on six populations (a total of 89 individuals) of Phytolacca dodecandra (endod) collected in Ethiopia. The populations were selected based on our previous investigation to represent two altitude groups: lowland/central-highland (1600–2500 m) and highland (2501–3000 m). A total of 197 AFLP and 68 RAPD markers were scored from 5 primer pairs and 12 random primers, respectively. The overall patterns obtained for AFLPs and RAPDs from diversity, cluster and principal component analyses were very comparable. However, the moderate correlation (r = 0.56) between AFLP and RAPD similarity matrices as well as the discrepancies in diversity estimates between the two techniques in some populations and in the lowland/central-highland plants could be due to differences in sensitivity of reaction conditions, bias in scoring of bands, number of markers used for analyses, and/or parts of the genome surveyed. For both AFLP and RAPD, the lowland/central-highland populations showed higher polymorphism and Shannon information measure (H) than the highlands. Cluster and principal component analyses performed for both marker types have also clearly demonstrated the differentiation of all the lowland/central highland plants from those of the highlands, in agreement with our previous conclusion. Markers scored from any of the five AFLP primer pairs were sufficient to clearly distinguish the two altitude groups; with RAPD, selection of about 8 informative markers produced by seven random primers was needed for the same purpose. 相似文献
7.
Louise Askaer Lea Bjerre Schmidt Bo Elberling Gert Asmund Ingibjörg S. Jónsdóttir 《Water, air, and soil pollution》2008,195(1-4):99-114
Impact of acid mine drainage (AMD) from a coal mine waste rock pile deposited within a permafrost-affected Arctic ecosystem was investigated near Longyearbyen (Svalbard, 78° N). Analyses included metal concentrations (Al, Fe, Mn, Zn, Ni, Cr, As and Pb) in runoff, soil and plants. It was observed that impacts of AMD, such as plant degradation, were similar to impacts reported from non-arctic ecosystems. It was found that bio-available metal concentrations in soil samples were not useful in assessing potential plant toxicity, as metals were not accumulated in the most impacted area due to low soil pH (pH?<?4). Native graminoid plants in the high impacted area showed accumulation of all the investigated elements. Al, Mn and As were found at phyto-toxic concentrations. Metal uptake in two native graminoid plants was studied in the laboratory. Positive correlations were noted between metal concentrations and plant uptake for all metals investigated, except Fe. High Fe concentrations found in plant samples in the impacted area are considered a result of Fe-oxide precipitation (plaque) on leaves during the spring flush when runoff covers the plants. We conclude that the weathering products Al, Mn and Fe induce the largest negative impact on vegetation in the area, and that a major fraction of the annual uptake of metals occurs during spring flushes. During these flushes, metals produced from weathering processes throughout the winter are released in high concentrations, coinciding with low pH values, low infiltration rates due to permafrost and the start of the plant growth season. 相似文献
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