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Shifa K.,Melkassa Agricultural Research Center | Getu E.,Addis Ababa Institute of Technology | Sori W.,Jimma University
Journal of Entomology | Year: 2014

Growth, development, reproduction and yield of silkworms depend on the availability and supply of preferred host plants having good agronomic and nutritional characteristics. Eri-silkworm, Samia cynthia recini B. is a multivoltine and polyphgous insect feeding on diversified host plants among which castor is a primary host plant. There is differential preference for the different varieties of castor by S.c. ricini. In the present study, eight different castor genotypes; namely Abaro, Acc 106584, Acc 203241, Acc 208624, Ar sel, Bako, GK sel and local were evaluated for their merits as feed and nutritional sources for white plain S.c. ricini at Melkassa Agricultural Research Center, Ethiopia. The treatments were arranged in a Completely Randomized Design (CRD) in three replications. Fifty worms were used in each replication. Significant difference was observed in rearing performance of eri-silkworms when fed to leaves of different castor genotypes. Among castor genotypes fed to eri-silkworm, Abaro fed worms showed medium to maximum records of matured larval weight (8.17 g), effective rate of rearing (74.68%), survival rate (76.08%), cocoon weight (3.34 g), pupal weight (2.86 g), shell weight (0.48 g), silk ratio (14.49%), fecundity (382.00), hatchability (88.17%) and shorter larval duration (584.17 h). In conclusion, genotype Abaro was superior to the other genotypes in improving the rearing performance of eri-silkworms and can be recommended for further research and development work in integrating silkworm activities for silk and oil seed productions. © 2014 Academic Journals Inc. Source

Hadgu G.,Haramaya University | Tesfaye K.,International Maize and Wheat Improvement Center | Mamo G.,Ethiopian Institute of Agricultural Research | Mamo G.,Melkassa Agricultural Research Center
Theoretical and Applied Climatology | Year: 2015

The impact of climatic change can be on specific locations. However, the broader the affected area coverage, in mind, the higher would be the chance in missing critical details. In this light, this paper attempts to assess the possible climatic changes and their corresponding implications on agricultural production in northern Ethiopia. The analysis is based on the future (2030 and 2050) temperature and rainfall data, downscaled as ensemble of four general circulation models (GCMs) using the A2 and B1 emission scenarios for ten meteorological stations located in different agroecological zones of the study region. The result indicates that, based on emission scenarios, the mean maximum and minimum temperature would increase by 2–2.3 and 0.8–0.9 °C in 2030 and by 2.2–2.7 and 1.4–1.7 °C in 2050, respectively. This will be accompanied by an increase in the frequency of hot days and nights and a decrease in cool days and nights. While annual rainfall totals will remain unchanged, main rainy season (kiremt) rainfall total would increase on average in 12.9 and 14.2 % under A2 and 9.5 and 11.2 % under B1 by 2030 and 2050, respectively. Owing to an increase in kiremt rainfall, the yield of maize and sorghum may increase at some sites under future climatic conditions, and the increase would be higher under CO2 fertilization. The results suggest the need for site-specific adaptation strategies to reduce the impact and/or exploit the opportunities of climate change. © 2014, Springer-Verlag Wien. Source

Adugna A.,Melkassa Agricultural Research Center | Adugna A.,Addis Ababa Institute of Technology | Bekele E.,Addis Ababa Institute of Technology
Plant Genetic Resources: Characterisation and Utilisation | Year: 2016

A study was carried out between 2008 and 2011 to investigate the potential risks of gene flow and its consequences in the crop–wild–weed S. bicolor complex in Ethiopia to aid efforts to conserve genetic diversity. Morphological measurements and genomic DNA samples were taken in situ from 30 wild and eight cultivated populations representing a total of 760 samples from five regions. Genetic diversity, gene flow, population structure and outcrossing rates of wild populations were computed using phenotypic measurements and/or polymorphic simple sequence repeat (SSR) markers. Moreover, morphological analyses of fitness of crop–wild hybrids were studied. High diversity was observed among the wild/weedy sorghum populations for phenotypic traits and SSRs. SSR diversity was high in both wild and cultivated populations, but the magnitude was greater in the former. Gene flow between the wild and the cultivated sorghum was observed to be higher than that within either pool. Wild sorghums exhibited variation in the multilocus outcrossing rate (range = 0.31–0.65) and fitness was not compromised in most wild × crop hybrids. The study indicated that crop-to-wild gene flow is possible in Ethiopia. Thus, genes from transgenic sorghum are expected to enter into the wild and non-transgenic cultivated populations and may spread and persist, if transgenic sorghum is deployed in Ethiopia and in other countries of Africa, which may pose risk of introduction of unwanted effects, which in turn may lead to loss of genetic diversity. Copyright © NIAB 2016 Source

Adugna A.,Melkassa Agricultural Research Center | Adugna A.,Addis Ababa Institute of Technology | Bekele E.,Addis Ababa Institute of Technology
Plant Genetic Resources: Characterisation and Utilisation | Year: 2015

Since the immediate wild relatives of Sorghum bicolor (L.) Moench are indigenous to Ethiopia, studying their population biology is timely for undertaking conservation measures. A study was conducted to investigate the occurrence of population bottlenecks and to estimate the long-term effective population size (N e) in wild relatives of sorghum. For this, 40 samples of wild sorghum were collected from two remotely located populations that were allopatric to the cultivated sorghum. The presence of bottlenecks was investigated using heterozygosity excess/deficiency, mode shift and allelic diversity based on nine polymorphic simple sequence repeat (SSR) loci. We also estimated the N e of the studied populations using two different methods employing SSR mutation models. The expected heterozygosity was found to be 0.41 and 0.71 and allelic richness was 3.0 and 4.9, in Awash and Gibe populations, respectively. Neither the heterozygosity excess nor the mode-shift methods detected signatures of bottlenecks in the studied populations. The effective size of the two wild sorghum populations studied also showed no risk of population reduction in these regions of Ethiopia. Therefore, these allopatric wild sorghum populations can survive by occupying patches by the roadsides and fences, areas within abandoned farm lands, forests, etc., which shows that their wild characteristics of adaptation have been adequate for them to survive from extinction despite extensive deforestation of their habitat for modern agriculture and frequent grazing by livestock. However, this does not guarantee the survival of these species for the future and ex situ conservation measures or policies could help maintain their diversity. © 2015 NIAB. Source

Wegary D.,Melkassa Agricultural Research Center | Wegary D.,University of the Free State | Labuschagne M.T.,University of the Free State | Vivek B.S.,Indian International Crops Research Institute for the Semi Arid Tropics
Field Crops Research | Year: 2011

Quality protein maize (QPM) breeding involves the combined use of the opaque-2 (o2) gene and the genetic modifiers of the o2 locus to develop cultivars with modified kernel endosperm, and increased concentrations of lysine and tryptophan. This study was designed to assess grain yield performance, endosperm modification, and protein quality and quantity under two contrasting soil nitrogen environments. A 15-parent diallel cross was evaluated under one low nitrogen stress and one optimal nitrogen environment each at Harare (Zimbabwe) and Bako (Ethiopia). Most QPM hybrids showed higher protein quality levels than the best non-QPM check under both conditions. Protein concentration tended to vary across nitrogen levels, but not endosperm type. Significant differences were found for the test of main effect (nitrogen-level) for endosperm modification and tryptophan concentration. This indicated that QPM maintains quality even under low soil nitrogen, a widespread condition in Africa. General combining ability (GCA) mean squares were highly significant for most protein quality traits for each environment and across environments whereas specific combining ability (SCA) mean squares were not significant in most cases. This indicated that additive gene effects were primarily responsible for variation of most traits evaluated and hence progeny performance can adequately be predicted on the basis of parental performance. Inbred lines P2, P4 and P12 had desirable GCA effects for endosperm modification while P1 and P3 had the best GCA for tryptophan concentration in grain. The current study suggests that hybrids with desirable endosperm modification, protein quality and stable performance under low nitrogen stress and optimal conditions can be produced with careful selection. © 2011 Elsevier B.V. Source

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