Tree planting for poverty reduction in less-favoured areas of the Ethiopian highlands

This paper assesses the potential impact of planting of eucalypt trees as a strategy to reduce poverty in a less-favoured area of the highlands of Ethiopia. Results from simulations with a bio-economic model for a less-favoured case study area in the highlands are combined with survey data at community, household and plot level to assess how general the results of the bio-economic model are. Application of the bio-economic model shows clearly that land degradation, population growth, stagnant technology and drought threaten food security. Household welfare and land quality are deteriorating rapidly in the area and interventions are urgently needed to avoid human disaster. Planting of eucalypts on land unsuitable for crop production may substantially increase household incomes if market outlets for trees can be found. Tree planting will not have severe negative effects on food production or land conservation. A policy combining promotion of tree planting and conservation of cropland may achieve win-win benefits in terms of increased household incomes as well as more sustainable land-use. Analysis of survey data from the Amhara Region of Ethiopia reveals that there is a large area of land that is unsuitable for crop production located close to all-weather roads in the less-favoured areas of the region. Few trees have been planted on this type of land up to now. The past policy seems to have discouraged tree planting except on homestead plots that are more suitable for food crops. This paper reports part of the IFPRI/ILRI project ‘Policies for Sustainable Land Management in the East African Highlands’. These two agencies have provided funds and logistical support for the work. The Norwegian Ministry of Foreign Affairs has provided funds for this research in the Amhara Region in Ethiopia. The authors also draw on earlier work funded by Research Council of Norway. Any correspondence should be directed to the first author.     

Effects of induction treatments on flowering in Populus deltoides

Stimulation of early flowering is required to shorten breeding cycles of eastern cottonwood (Populus deltoides Bartr. ex Marsh. var. deltoides), a commercially important and fast-growing hardwood species. A series of experiments was conducted to evaluate the influence of various treatments on flowering in rooted cuttings from mature and juvenile trees. A combined treatment of water stress, root pruning and paclobutrazol was applied to 3-month-old rooted cuttings from mature trees. These cuttings had been subjected to root restriction and long days. All treated plants flowered, whereas no untreated plants formed flower buds. One-year-old rooted cuttings from juvenile trees did not flower when treated with either paclobutrazol, paclobutrazol plus water stress, paclobutrazol plus root pruning, or paclobutrazol plus girdling. This was true both under continuous or periodic growth. Assessment of the lack of flowering in juvenile trees may require an integrated approach that investigates environmental or physiological stimuli, assimilate shift, gibberellic acid type and concentration, and flowering-time gene activity in the new shoots of mature and juvenile cottonwood trees.     

An explicit stem profile model for forked and un-forked teak (Tectona grandis) trees in West Africa

Studies on stem profile of teak (Tectona grandis) hardly exist. This can be possibly attributed to the occurrence of forks that is prevalent on teak trees. Stem profile model was therefore developed for teak in West Africa, which took into account the occurrence of forks. Trees were destructively sampled from Moist Evergreen Forest (MEF), Moist Semi-deciduous Forest (MSDF), Dry Semi-deciduous Forest (DSDF) and Savannah ecological zones in both Ghana and Côte d’Ivoire for the study. A single set of parameters could be used explicitly to predict stem profile of any teak tree, irrespective of country, eco-climatic zone, edaphic variables, site index, tree age, stand density and tree competition. The model efficiency and root mean square error (in relative diameter) were calculated to be 0.97 and 0.053, respectively. The relative position of the forks along the stem bole, with respect to total tree height, was highly variable and did not follow any particular trend, except higher value for the first fork in the Moist Evergreen Forest zone. However, average tree height to the first fork decreased along the ecological gradient from MEF, MSDF and DSDF to Savannah. The extent of diameter reduction due to the forks could be predicted. Relative tree form for zero-forked, one-forked and two-forked trees was calculated to be 0.39, 0.36 and 0.33, respectively. Relative loss of stem volume due to one fork and two forks was estimated to be 6.5 and 13.9%, respectively. The measured stem volume when related to the corresponding predicted value yielded coefficient and intercept not significantly different from unity and zero, respectively, with an r² value of 0.97.     

Genetic diversity of winter wheat in Shaanxi province, China, and other common wheat germplasm pools

Cultivated Chinese wheat germplasm has been a valuable genetic resourcein international plant breeding. Landraces endemic to China are a geneticresource that is distinct from other wheat germplasm. Patterns of geneticdiversity among cultivated Chinese accessions and relationship to othergermplasm pools are unknown, despite the proven value and potential novelty. Theobjective of this work was to determine the level of genetic diversity withinimproved Chinese germplasm in the context of several other wheat germplasmpools. We analyzed a set of improved accessions cultivated from the 1940s to the1990s in Shaanxi province, China, using six simple sequence repeat (SSR) primerpairs and 30 restriction fragment length polymorphism - probe enzymecombinations (RFLP-PEC) previously used to characterize 21 geographically basedgermplasm pools. Shaanxi germplasm consists of three groups based on foreignintroductions from Italy, Australia, Denmark, and Russia. There was a decreasein genetic diversity among Shaanxi accessions cultivated in the 1970s and 1980sto the 1990s, and accession classifications based on primary decade ofcultivation were found to be significantly undifferentiated. The analysis of themean genetic distance among 22 geographically based pools of germplasm suggestsseveral regions are significantly undifferentiated. A vast majority of the totalamount of variation was found within pools; therefore, pools appear to belargely differentiated based on small differences in band relative frequency andfew if any unique bands. Previous studies have identified some Chinese landracepools as morphologically and genetically unique. The Shaanxi pool does not havethe same unique morphological or genetic features, nor is it more similar to thelandrace pools than other improved germplasm pools.     

Effects of gaseous pollutants on forests in Eastern North America

The purpose of this paper is to summarize the current state of knowledge concerning direct forest damage caused by atmospheric gaseous pollutants. The major gaseous pollutants affecting forest growth are O₃, SO₂, and HF. Ozone is the most prevalent phytotoxic air pollutant on a regional scale in eastern North America. It has been demonstrated to cause foliar injury and growth effects on trees in both laboratory and field studies. Both SO₂ and HF have been found to cause damage to forests primarily in the vicinity of strong point sources. Case histories of forest damage are reported in the paper which describe foliar and radial growth effects, with associated volume losses. Threshold levels of the gaseous pollutants causing effects on forest growth are provided.     

Influence of aroma compounds on the mechanical properties of pectin gels

A detailed study of the rheological behavior of pectin gels, in the presence of aroma compounds in food concentration is reported. In high methoxylated pectin (HMP) gels, it has not yet been shown if aroma compounds can be responsible for modifications in rheology. Two rheological techniques were used to measure the impact of aroma substances on rheological properties of HMP-based systems. Maximum strain to fracture (sigma F) was compared between flavored and unflavored gels on stress-displacement curve, which was obtained with uniaxial compression until fracture. An oscillatory rheometer was applied to determine the gelation time (Tgel). It appeared that all the aroma compounds studied increased significantly sigma F. It is generally acknowledged that hydrophobic interactions are the main interactions leading to HMP gelation, and the more hydrophobic interactions there are, the higher the sigma F. It is assumed that esters might increase sigma F through the increase of hydrophobic interactions in HMP network. For solvents (ethanol, propylene glycol), a cosolute effect could explain the increase in firmness for HMP-based gels.     

Comparative Study of the Adsorption Selectivity of Cr(VI) onto Cationic Hydrogels with Different Functional Groups

Two types of hydrogels with different functional groups, trimethylamine on quaternary ammonium and dimethylethoxyamine on quaternary ammonium, were synthesized. Type 1 and type 2 hydrogels were characterized with Fourier transform infrared, X-ray photoelectron spectroscopy and zeta potential analysis. The anion selectivity of these two hydrogels was investigated. The surface charges of the type 2 hydrogel were lower than those of type 1, probably because of the presence of the hydroxyl group in the ethoxy group. The Cr(VI) removal capacity of type 2 hydrogel was, therefore, less than that of type 1 hydrogel, although their adsorption rates were similar. The anion selectivity of the hydrogels was found to have a similar order: Cr(VI) > sulphate > bromide > As(V). Under the co-presence of Cr(VI) and sulphate conditions, type 2 hydrogel shows a higher selectivity towards Cr(VI). The higher hydrophobicity was caused by the presence of the ethoxy group on the quaternary ammonium in type 2 hydrogel and thus increased in selectivity towards monovalent ions (i.e. HCrO₄⁻). In addition, the hydrogels have a high reusability. Compared with type 1 hydrogel, type 2 hydrogel has an advantage for applications in Cr(VI) removal and recovery processes.     

COLOR DOPPLER ULTRASONOGRAPHY IN PREDICTION OF THE REDUCIBILITY OF INTUSSUSCEPTED BOWEL IN 15 YOUNG DOGS

Color Doppler ultrasonography was performed in 15 young dogs with intestinal intussusception to test the hypothesis that color Doppler findings can be used as a predictor of the manual reducibility of the intussusception at celiotomy. Color flow Doppler ultrasonography indicated blood flow within mesentery of the intussuscepted bowel in 12 of 15 dogs and reduction was achieved in nine of these 12 dogs (75%). In the remaining three dogs and in three dogs where no color Doppler signal were observed, an irreducible intussusception was confirmed at celiotomy. Color Doppler ultrasonography is a useful method for predicting the reducibility of intussusception in dogs.     

基于修正双作物系数模型估算温室黄瓜不同季节腾发量

为估算温室黄瓜植株蒸腾与土面蒸发,该研究基于FAO-56推荐的双作物系数模型,应用温室内实测微气象、叶面积指数(LAI)及土壤水分数据,对模型中基础作物系数(Kcb)和土面蒸发系数(Ke)进行修正,并基于修正后FAO-56Penman-Monteith(P-M)模型,确定温室参考作物蒸发蒸腾量(ET0),进而估算温室黄瓜蒸发蒸腾量(ETc)和植株蒸腾(Tr)。基于Venlo型温室内黄瓜不同种植季节(春夏季和秋冬季)Lysimeter和茎流计观测的黄瓜ETc和Tr,对修正后的双作物系数模型预测结果进行验证。结果表明,应用修正后的双作物系数模型估算的温室黄瓜ETc和Tr与实测值具有较好地一致性,春夏季温室黄瓜全生育期ETc估算值与实测值的日均值分别为3.05和2.94 mm/d,秋冬季分别为2.53和2.76 mm/d。修正后的双作物系数模型估算春夏季温室黄瓜日ETc的决定系数(R2)、均方根误差(RMSE)和模型效率系数(Ens)分别为0.95、0.41 mm/d和0.93;估算秋冬季ETc的误差计算结果依次为0.91(R2)、0.48 mm/d(RMSE)和0.90(Ens)。修正后的双作物系数模型估算春夏季日平均Tr与实测值分别为2.37和2.19mm/d,秋冬季分别为1.43和1.34 mm/d。研究结果还显示,不同种植季节温室黄瓜全生育期日平均Tr占ETc的比例分别为64.62%(春夏季)和68.59%(秋冬季)。该研究成果不仅为制定准确的温室黄瓜灌溉制度提供了理论依据,而且对实现温室环境智能化控制及减少温室内无效的土面蒸发具有重要意义。     

The generation and persistence of genetic variation in foot-and-mouth disease virus

Genetic variation in foot-and-mouth disease virus (FMDV) is of interest for at least two reasons. First, changes to the genes encoding capsid proteins results in antigenic variation, and affects vaccine efficiency and effectiveness of vaccination programs; second, genetic changes can lead to important insights into the transport of virus between countries, regions, herds, and even possibly individuals. Current estimates of RNA virus mutation rates suggest that an average of about one base mis-incorporation is likely to occur each time a single FMDV genome replicates. This should result in the introduction of every possible 1-step mutation from the progenitor genotype into the viraemia of a single infected animal many times a day. In the absence of purifying selection, a single infected animal should therefore generate a genetically very diverse population of virus.Viral-capsid sequences obtained from infected animals sampled over long-term FMDV epidemics suggest that these genetic changes accrue in a remarkably linear 'clock-like' fashion and at rates of around 1% change per year. While such a rate is generally regarded as quite high, it is actually somewhat lower than one might expect based on the rate at which viral diversity could be generated within a single animal. The difference might be explained in a variety of possible ways: (1) the mutation rate has been overestimated; (2) purifying selection is stronger than predicted; (3) only a restricted subset of excreted virus is actually infectious; (4) infected animals only excrete virus from a small partitioned subset of amplified virus, and that most of the generated viral diversity is unable to exit the animal; or (5) only a small fraction of all infected animals participate in the actual disease-transmission process.