18 research outputs found
Nitrogen response functions targeted to technology extrapolation domains in Ethiopia using CERES-maize
The profitability of fertilizer-N use can be optimized using N response functions specific to climate-based technology extrapolation domains (TED). Crop growth simulation can complement field research for targeting of response functions. The objective of this study was to target maize (Zea mays L.) N response functions to seven TED in Ethiopia through CERES-Maize simulation of continuous maize over 30 yr. The complete factorial set of treatments included seven levels of N in 25 kg ha−1 increments under no-till (NT) and conventional tillage (CT) systems. The CERES-Maize simulated experiments were done for two or three sites per TED. Nitrogen response functions were generated for each TED with tillage-specific functions for three TED with tillage × N interactions. The N rate responses for all TED fit curvilinear to plateau functions but with differing magnitudes and shapes of response. The mean yield with NT was 6% less than with CT, but the difference declined with increased N rate. The economically optimum N rate (EONR) ranged from 65 to 179 and 103 to 243 kg ha−1 for high and low-cost fertilizer-N, respectively. The EONR was 6% less and the profit cost ratio was 11% higher with CT compared to NT, indicating greater fertilizer-N need with NT than with CT. The application of N for maize was highly profitable for all TED. The EONR from CERES-Maize were higher than past field research results. This suggests that the CERES-Maize N response functions were most appropriate for well-managed crop production situations in Ethiopia
Factors that transformed maize productivity in Ethiopia
Published online: 26 July 2015Maize became increasingly important in the food
security of Ethiopia following the major drought and famine
that occurred in 1984. More than 9 million smallholder house-
holds, more than for any other crop in the country, grow maize
in Ethiopia at present. Ethiopia has doubled its maize produc-
tivity and production in less than two decades. The yield,
currently estimated at >3 metric tons/ha, is the second highest
in Sub-Saharan Africa, after South Africa; yield gains for
Ethiopia grew at an annual rate of 68 kg/ha between 1990
and 2013, only second to South Africa and greater than
Mexico, China, or India. The maize area covered by improved
varieties in Ethiopia grew from 14 % in 2004 to 40 % in 2013,
and the application rate of mineral fertilizers from 16 to 34 kg/
ha during the same period. Ethiopia
’
s extension worker to
farmer ratio is 1:476, compared to 1:1000 for Kenya, 1:1603
for Malawi and 1:2500 for Tanzania. Increased use of im-
proved maize varieties and mineral fertilizers, coupled with
increased extension services and the absence of devastating
droughts are the key factors promoting the accelerated growth
in maize productivity in Ethiopia. Ethiopia took a homegrown
solutions approach to the research and development of its
maize and other commodities. The lesson from Ethiopia
’
s
experience with maize is that sustained investment in agricul-
tural research and development and policy support by the
national government are crucial for continued growth of
agricultur
Genetic studies of extra-early provitamin-A maize inbred lines and their hybrids in multiple environments
Open Access Article; Published online: 25 Sept 2019Vitamin A deficiency, drought, low soil nitrogen (low N) and Striga hermonthica parasitism of maize (Zea mays L.) cause malnutrition and food insecurity in sub-Saharan Africa. The objectives of this study were to determine combining abilities of extra-early provitamin A (PVA) lines, classify them into heterotic groups (HGs), identify testers, and determine yield stability of hybrids under contrasting environments in two trials. In trial 1, 20 extra-early PVA lines were inter-mated in a diallel mating scheme to obtain 190 F1 hybrids. The 190 F1 hybrids plus six checks were tested under Striga infestation, drought, and stress-free environments in Nigeria from 2015 to 2017. In trial 2, 35 extra-early yellow hybrids were evaluated under low-N, Striga-infested and stress-free environments in 2018. Provitamin A concentrations of 23.98 and 22.56 μg g-1 were obtained for TZEEIOR 202 and TZEEIOR 205. TZEEIOR 197 × TZEEIOR 205 (20.1 μg g-1) and TZEEIOR 202 × TZEEIOR 205 (22.7 μg g-1) contained about double the PVA level of the commercial check, TZEEI 58 × TZEE-Y Pop STR C5 (11.4 μgg-1). Both general (GCA) and specific (SCA) combining ability variances were statistically significant for most agronomic traits, although GCA was much larger than SCA effects, indicating that additive genetic effects primarily controlled the inheritance of those traits. TZEEIOR 97 and TZEEIOR 197 were identified as inbred testers. TZEEIOR 197 × TZEEIOR205 (20.1 μg g-1) was identified as a single-cross tester as well as the most stable and highest-yielding hybrid across environments. TZEEIOR 202 and TZEEIOR 205 should be invaluable resources for breeding for high PVA. PVA level was independent of hybrid yield potential, indicating that selection of superior hybrids with elevated PVA levels should be feasible
Protein quality and endosperm modification of quality protein maize (Zea mays L.) under two contrasting soil nitrogen environments
Molecular genetic diversity and population structure of Ethiopian white lupin landraces: Implications for breeding and conservation
White lupin is one of the four economically important species of the Lupinus genus and is an important grain legume in the Ethiopian farming system. However, there has been limited research effort to characterize the Ethiopian white lupin landraces. Fifteen polymorphic simple sequence repeat (SSR) markers were used to assess the genetic diversity and population structure of 212 Ethiopian white lupin (Lupinus albus) landraces and two genotypes from different species (Lupinus angustifolius and Lupinus mutabilis) were used as out-group. The SSR markers revealed 108 different alleles, 98 of them from 212 landraces and 10 from out-group genotypes, with an average of 6.5 alleles per locus. The average gene diversity was 0.31. Twenty eight landraces harbored one or more private alleles from the total of 28 private alleles identified in the 212 white lupin accessions. Seventy-seven rare alleles with a frequency of less than 5% were identified and accounted for 78.6% of the total alleles detected. Analysis of molecular variance (AMOVA) showed that 92% of allelic diversity was attributed to individual accessions within populations while only 8% was distributed among populations. At 70% similarity level, the UPGMA dendrogram resulted in the formation of 13 clusters comprised of 2 to 136 landraces, with the out-group genotypes and five landraces remaining distinct and ungrouped. Population differentiation and genetic distance were relatively high between Gondar and Ethiopian white lupin populations collected by Australians. A model-based population structure analysis divided the white lupin landraces into two populations. All Ethiopian white lupin landrace populations, except most of the landraces collected by Australians (77%) and about 44% from Awi, were grouped together with significant admixtures. The study also suggested that 34 accessions, as core collections, were sufficient to retain 100% of SSR diversity. These accessions (core G-34) represent 16% of the whole 212 Ethiopian white lupin accessions and populations from West Gojam, Awi and Australian collections contributed more accessions to the core collection
Pedological characterization, fertility status and classification of the soils under maize production of Bako Tibe and Toke Kutaye Districts of Western Showa, Ethiopia
Ethiopian journal of applied science and technology, 2016; 7 (1): 18-33Maize farm fields were selected in two districts of western Showa, Ethiopia. Four representative maize fields were
selected based on landforms and other physiographic attributes in humid highland and sub humid mid altitude areas
of Toke Kutaye and Bako Tibe Districts. The objective was to characterize and classify the soils under maize
production in Toke Kutaye and Bako Tibe Districts of western Showa, Ethiopia. Four soil profiles were opened and
characterized. Pedons are formed under udic and perudic moisture and iso-thermic temperature regimes for both
districts. The soils were very deep, well-drained reddish brown to dark reddish brown loamy sand to sandy clay
loams, with thick reddish brown loamy sand top and sub soil for Bako Tibe and Toke Kutaye. Three pedons had
clayey top and sub soils. The pH of surface soil ranged from 4.48-5.52 which was very strongly acidic to strongly
acidic. The soil organic carbon contents of the topsoil and subsoil of the four pedons ranged from 2.07 to 2.69% and
0.35 to 2.85 %, which were rated as medium to high, but very low to high respectively. Both two highland pedons
had CEC ranging from 20.06 to 54.17 cmol c kg -1 soil, which was rated as medium to very high, while in the two mid
altitude pedons it ranged from 10.82 to 23.52 cmol c kg -1 soil CEC, which was low to medium. The total nitrogen levels
ranged from 0.19 to 0.23% for topsoils, which was low to medium, and from 0.03 to 0.07 % for subsoils, which was
very low. According to USDA Soil Taxonomy, the four pedons were classified as Typic Palehumults (Acrisols and
Alisols according to WRB). The four pedons were different in physicochemical properties, indicating the need to
characterize soils to give site-specific fertilizer recommendations for maize production
Major biotic maize production stresses in Ethiopia and their management through host resistance
Biotic stresses are recently evolving very rapidly and posing significant yield losses of maize production in Ethiopia. A number of high yielding maize hybrids, initially developed as tolerant/resistant, have been taken out of production due to their susceptibility to major maize diseases. Furthermore, recent disease and insect pest epidemics have clearly shown the importance of breeding maize for biotic stresses and study the genetics of resistance to the major maize disease pathogens, insect pests and parasitic weeds. This paper gives the general perspective of the major biotic maize production stresses in Ethiopia and the interventions made locally and globally to control these stresses using host resistance. More emphasis was given to grey leaf spot (GLS), turcicum leaf blight (TLB), common leaf rust (CLR), maize streak disease (MSD), maize lethal necrosis (MLN), maize weevil, stalk borers, fall armyworm and Striga. Approaches to conducting genetic analysis and achieving durable host resistance to these stresses, where applicable, are discussed. This information will be used for breeders, private and public maize seed and grain growers who are targeting to operate in Ethiopia and Eastern Africa
Crop diversification and productivity in semiarid and sub-humid maize-legume production systems of Ethiopia
Sources of tolerance to low soil nitrogen in some Striga resistant and quality protein maize (Zea mays L.) varieties
Genetic gains in early maturing maize hybrids developed by the International Maize and Wheat Improvement Center in Southern Africa during 2000–2018
Genetic gain estimation in a breeding program provides an opportunity to monitor breeding efficiency and genetic progress over a specific period. The present study was conducted to (i) assess the genetic gains in grain yield of the early maturing maize hybrids developed by the International Maize and Wheat Improvement Center (CIMMYT) Southern African breeding program during the period 2000–2018 and (ii) identify key agronomic traits contributing to the yield gains under various management conditions. Seventy-two early maturing hybrids developed by CIMMYT and three commercial checks were assessed under stress and non-stress conditions across 68 environments in seven eastern and southern African countries through the regional on-station trials. Genetic gain was estimated as the slope of the regression of grain yield and other traits against the year of first testing of the hybrid in the regional trial. The results showed highly significant (p< 0.01) annual grain yield gains of 118, 63, 46, and 61 kg ha−1 year−1 under optimum, low N, managed drought, and random stress conditions, respectively. The gains in grain yield realized in this study under both stress and non-stress conditions were associated with improvements in certain agronomic traits and resistance to major maize diseases. The findings of this study clearly demonstrate the significant progress made in developing productive and multiple stress-tolerant maize hybrids together with other desirable agronomic attributes in CIMMYT’s hybrid breeding program