Invasion of Prosopis juliflora and its effects on soil physicochemical properties in Afar region,Northeast Ethiopia

Woody species within pastures and savannas are often associated with ‘resource islands’ characterized by higher fertility under canopies trees. The aims of this study were to evaluate (1) the effects of Prosopis juliflora on some soil physicochemical properties and (2) the impacts of Prosopis invasion on soil salinity. For soil physicochemical analysis, a total of 104 soil samples from Teru and Yalo Districts were collected. The soil samples were collected from soil depths of 0–15 cm and 15–30 cm in Prosopis invaded and non-invaded open grazing lands. Invasion of Prosopis had significantly affected soil pH, exchangeable Na⁺, water soluble Ca²⁺ + Mg²⁺, water soluble Na⁺, and exchangeable sodium percentage in Teru and Yalo Districts (p < 0.05). The invasion of Prosopis significantly increased soil pH (1.5%), but decreased exchangeable Na⁺ (24.2%), exchangeable sodium percentage (21.6%), and water soluble Ca²⁺ + Mg²⁺ (39.9%) than non-invaded lands. Clay content of Prosopis invaded lands was higher by 19% than non-invaded lands. However, sand content of soil was higher under non-invaded lands by 5.6% than Prosopis invaded lands. Most results indicated that invasion of Prosopis had positive effects on physicochemical properties and thus conducive for cereal crops and forages.     

Evaluation of 20 enset (Ensete ventricosum) landraces for response to Xanthomonas vasicola pv. Musacearum infection

Xanthomonas wilt, caused by Xanthomonas vasicola pv. musacearum (Xvm), formerly X. campestris pv. musacearum, is the most threatening and economically important disease of enset (Ensete ventricosum), the multipurpose food security crop orphan in south and southwestern Ethiopia. Xvm has also had a major impact on banana and plantain production in east Africa following its detection in Uganda in 2001 and subsequent spread. The only current effective control of this disease relies on integrated disease management strategies including minimizing field pathogen inoculum and deployment of wilt-resistant enset landraces. Identifying landraces with stable and durable Xvm resistance will greatly accelerate breeding programmes. While previous reports have identified landraces with varying degrees of tolerance to Xvm, no systematic study has collectively assessed their relative resistance. Here we undertook a detailed “common garden” analysis of 20 enset landraces previously reported to exhibit lower susceptibility to Xvm using an aggressive Xvm inoculum isolated from a disease hotspot area. Detailed longitudinal and survival analyses were applied to each landrace, using a combination of area-under-disease progress stairs, disease index and apparent infection rate to capture disease metrics as well as disease progression symptoms. Considerable variation was observed among the 20 landraces; however, none exhibited full immunity to Xvm infection. Landraces Haella, Mazia and Lemat showed the lowest susceptibility to Xvm as evidenced by reduced disease units and higher survival rates compared to the susceptible control landrace Arkiya, which exhibited the highest infection level and lowest survival rate, consistent with a high degree of susceptibility to Xvm. Thus, we have in this controlled experiment identified new material suitable for incorporation into future breeding programmes to develop Xvm-resistant enset varieties.

     

Status and trends of the processed wood products trade in Ethiopia

ABSTRACT

Information on the trends of the processed wood products (PWP) trade in Ethiopia is lacking. Therefore, the objectives of this article are (a) to evaluate the trends of expenses from importing and incomes generated from exporting different PWP, (b) to assess the PWP trade balance, and (c) to forecast future ex-penses in importing PWP. To achieve the objectives, import and export data of PWP in the years of 2005–2013 were collected. The data were analyzed using Pearson’s correlation. The trend of expenses was analyzed using Excel and future expenditures were forecasted by models for each PWP, independently. The result indicated that, Ethiopia spent on average, US$55.2 million/yr to import different PWP. The trend of expenses to import different PWP increased by 13% each year. There was a strong and positive correlation between the average yearly expenses to import different PWP with that of the population of the country in different years’ time (R² = .80) and also the GDP of the country in different years’ time (R² = .87). Overall, the results showed the self–insufficiency of the country in producing different PWP and the heavy expenditure to import wood products to fill the gap.     

巨桉(Eucalyptus grandis)植被和其相邻的山地雨林中土壤营养的评价

A study was conducted to evaluate the status of soil nutrients under E. grandis plantation in comparison with that in its adjacent submontane rain forest. Twenty sequare plots, with an area of 20 m×20 m for each, were established in both of E. grandis plantation and its adjacent sub-montane rain forest, independently. Soil samples were collected from each square plot, at five points (at the four corners and at the center) of each plot. The collected soil samples were mixed to make a composite and representative sample for each plot, independently. The analyses were done in a soil laboratory following appropriate methods. The analysis result indicated that there were no significance differences between E. grandis plantation and its adjacent sub-montane rain forest in the level of major soil nutrients (total N, available P, exchangeable K, Ca and Mg), pH and total carbon of soils (p < 0.05). There were significance differences between two sites of forest soils in percentage of clay particles, and exchangeable Na content. E. grandis plantation was found improving soil nutrients and total carbon as compared with that of its adjacent submontane rain forest.     

The metal silo: An effective grain storage technology for reducing post-harvest insect and pathogen losses in maize while improving smallholder farmers’ food security in developing countries

Traditional storage practices in developing countries cannot guarantee protection against major storage pests of staple food crops like maize, leading to 20-30% grain losses, particularly due to post-harvest insect pests and grain pathogens. As a result, smallholder farmers end up selling their grain soon after harvest, only to buy it back at an expensive price just a few months after harvest, falling in a poverty trap. The potential impact on poverty reduction and greater livelihood security will not be realized, however, if farmers are unable to store grains and sell surplus production at attractive prices. Apart from causing quantitative losses, pests in stored grain are also linked to aflatoxin contamination and poisoning. To address this problem, a metal silo was developed as a valid option and proven effective in protecting stored grains from attack by storage insect pests. A metal silo is a cylindrical structure, constructed from a galvanized iron sheet and hermetically sealed, killing any insect pests that may be present. The impact of metal silo technology in Africa, Asia and Latin America includes, improving food security, empowering smallholder farmers, enhancing income opportunities and job creation, and safeguarding the agro-ecosystems. The metal silo can be fabricated in different sizes, 100 kg-3000 kg holding capacity by trained local artisans, with the corresponding prices of $35 to $375. The use of metal silo, therefore, should be encouraged in order to prevent storage losses and enhance food security in developing countries.     

A cross-sectional study of epizootic lymphangitis in cart-mules in western Ethiopia

A cross-sectional study was conducted to determine the prevalence of epizootic lymphangitis (EL) in 309 cart-mules (cart-pulling mules) in Bako and Ejaji towns, Western Ethiopia using clinical and microbiological examinations, between November 2002 and April 2003. The overall prevalence was 21% (CI = 16.6–26%). The clinical, histological and mycological characteristics of EL in a cart-mule were similar with those in a horse. There was significant (χ² = 133.5, P = 0.001) association between tick infestation and EL lesions in study cart-mules. Amblyoma coherence and Boophilus genera were the ticks collected from lesions of cases of EL, and thus played a predisposing role. In conclusion, our results showed that EL has high prevalence in cart-mules in the two towns.     

In vitro pre-exposure of Haemonchus contortus L3 to blood eosinophils reduces their establishment potential in sheep

Different authors have reported that eosinophils are capable of immobilising infective larvae of different species of nematodes in vitro. However, classifying larvae as mobile or immobile is so subjective that it does not always mean all apparently immobile larvae are dead or those that are mobile are capable of surviving further immune responses if administered to their natural hosts. The objective of this experimental study was therefore to substantiate the role of eosinophils in the killing of Haemonchus contortus infective larvae by comparing the infectivity in sheep of larvae that had been incubated with eosinophil-enriched cell suspensions with control larvae. Since it was not possible to isolate pure eosinophils from sheep blood, we were compelled to evaluate the effects of other blood cells contaminating our eosinophil-enriched suspensions. Although eosinophils and neutrophils were the only cells found adherent to H. contortus infective larvae in vitro, induced eosinophils in the presence of immune serum were primarily responsible for the drastic reduction in larval motility compared to the minor effects of neutrophils and mononuclear cells. Corresponding reductions in faecal egg count and worm numbers were observed when the incubated larvae were transferred intra-abomasally to sheep. Interestingly, the proportion of larvae that failed to establish was much higher following incubation with induced eosinophils compared with other cells or with immune serum alone. Although this study did not address the in vivo role of eosinophils in sheep, the results strongly indicate that sheep blood eosinophils have a larval killing potential in vitro, and a larval mobility test alone may not fully explain the level of damage inflicted on the larvae.