Browsing by Author "Hailu, Hiwot"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Growth and Physiological Response of Two Coffea arabica L. Populations under High and Low Irradiance
    (Addis Ababa University, 2011-01) Hailu, Hiwot; Fetene, Masresha(Professor)
    The objective of this study was to evaluate the effects of varying irradiance on the growth and physiology of Coffea arabica. Growth measurements such as stem height (SH), number of branches (NB), stem girth (SG), internode length (IL) and specific leaf area (SLA) were measured, whereas, net assimilation rate, transpiration rate and water use efficiency were measured for gas exchange measurements. Two Coffea arabica populations (Bale and Sheko) were grown in pots placed in the greenhouse of Addis Ababa University under two irradiance regimes, high irradiance (HI)/direct sunlight and 20% of shade (20% HI) for six months. The result of this study shows that stem height, number of branches and stem girth was found higher for exposed coffee plants than the shaded in both populations. However, the Bale coffee population achieved higher growth rate than Sheko coffee population under their respective irradiance level with respect to the three parameters. Specific leaf area in shaded coffee plants was found to be higher than exposed in both populations. But under shade environment, Sheko coffee plants attained lower value than Bale, where, under high irradiance the reverse is achieved. Internode length was also higher in shaded coffee plants of Bale populations, whereas, it showed the same growth with exposed ones in Sheko populations. For internode length, Shaded Bale coffee plants showed higher growth rate than shaded Sheko coffee plants. But under high irradiance Sheko coffees achieved higher value than Bale. As stated for gas exchange measurements, net assimilation rate (Anet) and stomatal conductance (gs) for exposed coffee plants was higher in both populations than shaded. But transpiration rate (E) for both coffee populations under direct sunlight was found lower than under shade. Compared to Sheko coffee plants, Bale coffees showed higher value for daily integrated net assimilation rate and transpiration rate under their respective irradiance level. Moreover, as a result of higher net assimilation rate and lower transpiration rate in exposed coffee plants, it was expressed that integrated daily water use efficiency (WUE) was found higher in exposed coffee trees in both populations. And comparing the two populations, under high irradiance Bale coffees exhibited higher daily integrated water use efficiency than Sheko, while both populations showed similar value under shade. Exposed Bale coffee plants had higher light saturated rates of photosynthesis than the shaded one, which shifted from 200 μ mol Photons m-2 s-1 to 600 μ mol Photons m-2 s-1. But leaves of Sheko coffee trees under high and low irradiance levels were saturated between 800 μ mol Photons m-2 s- and 900 μ mol Photons m-2 s- respectively. Furthermore, it is observed from the result that the coffee plants exhibited substantial phenotypic plasticity for most of growth and physiological traits in response to varying irradiance level; thereby the magnitude of plasticity differed markedly among the populations. In particular, plants originating from drier climate (Bale region) showed the highest amount of plasticity suggesting fast adaptation to changing irradiance. These results suggest that this species performs well under high irradiance light though it has been grouped under shade adapted plants .It provides the growth and physiological response and reveal the difference among the two coffee populations in morpho-physiological characteristics. This differential response to light conditions may contribute to its ability to succeed in natural and agricultural environments or to endure control strategies. Moreover, this study contributes as baseline information for further research on the management and use of coffee production. Key words: Coffee, Growth, Net CO2 assimilation, Stomatal conductance, Internal CO2 concentration, Irradiance Photosynthetic active radiation
  • No Thumbnail Available
    Item
    Impacts of Adopting Improved Wheat Varieties on Food Security In Girar Jarso Woreda, North Shewa Zone, Oromia Region, Ethiopia
    (Addis Ababa University, 2018-06) Hailu, Hiwot; Tolossa, Degefa (PhD)
    The aim of this study is to assess impacts of adopting improved wheat varieties on food security in Girar JarsoWoreda, Oromia Region, Ethiopia. From Girar Jarso Woreda, three Kebeles are selected. A sample of 192 households comprised of 90 adopters and 102 non- adopters, were selected by using multistage sampling procedure. Both qualitative and quantitative data were collected from primary and secondary sources. Household survey, key informant interview of sample farmers and focus group discussion and review of reports were the means used to collect the data. The study used descriptive statics such as mean, standard deviation, frequency, percentage, t-test, and chi-square test methods for data analysis. A non-parametric estimation of Propensity Score Matching method and a parametric method of Logit model were employed. The researcher used a logit model to identify factors affecting adoption of improved wheat varieties and applied the Household Food Balance Model (HFBM) to quantify the net available food at household level. A Propensity Score Matching (PSM) method is also used to estimate the impact of improved wheat varieties on food security of the rural households. Hidase and Digelu ,Danda’a and Kubsa were types of improved Wheat varieties cultivated by adopters in the production year of 2017/2018. The results revealed that Education status , participation in demonstration and field day and activities , distance to the market, access to market information and member of farmer cooperative were significantly affect adoption decision of improved wheat varieties. The result of impact of improved wheat varieties on food security shows that, households that use improved wheat varieties tend to get higher kilocalorie available food and have higher consumption expenditure at household level than those who do not adopt. The study has also indicated that adopting of improved wheat varieties had a potential of increasing availability of food at household’s level. Governmental and non-governmental organizations in the study area should give due attention for adoption of improved varieties to minimize the problem of food insecurity in the study area. Keywords: Impact of improved Wheat Varieties, Household Food Security, Households in Girar Jarso Woreda