ETHIOPIAN AGRICULTURAL RESEARCH INSTITUTE
P.O. Box 2003, Addis Ababa, Ethiopia.
The adoption of bread wheat production technologies in the Arsi Zone. [p. 44]
Setotaw Ferede, D.G. Tanner, H. Verkuijl, and Takele Gebre.
Tremendous efforts have been exerted towards the development
and dissemination of improved bread wheat production technologies
in the Arsi Zone of Ethiopia since the inception of comprehensive
integrated package projects in the late 1960s. The current study
examined the rate of adoption of wheat production technology and
identified factors influencing the adoption of those technologies.
A total of 300 farm households were surveyed in the five major
wheat-growing areas of the Arsi Zone during May 1999. About 95
% of the sampled farmers had grown wheat during the 1998 crop
season. The farmers sampled produced a total of 13 different wheat
varieties during 1998. Survey results revealed that 91.5 % of
the farmers adopted improved bread wheat varieties. Kubsa (39
% of growers) and Pavon (25 % of growers) were the two most widely
adopted varieties in the region. In terms of the total wheat area,
the six dominant varieties covered 92.5 % of the wheat area, whereas
semidwarf bread wheat varieties occupied 88.5 % of the total wheat
area. About 73 % of wheat growers planted a single variety of
wheat. DAP and urea fertilizers were adopted by 92 and 26 % of
the wheat growers, respectively. More than half of the fertilizer
users (57.6 %) applied DAP on wheat fields at a rate between 76
and 100 kg/ha. The level of urea application was quite low. The
mean urea application rate was 17.5 kg/ha among the sampled wheat
growers. About 32 % of the urea was top dressed. Only about 15
% of the wheat growers adopted the current, blanket fertilizer
recommendation (100 kg/ha DAP and 100 kg urea/ha) on wheat fields.
Although the majority of the wheat growers (84 %) practiced hand
weeding, about 63 % used chemical weed control, frequently at
suboptimal rates. On average, wheat growers applied 0.46 l of
2,4-D herbicide per ha of wheat. Finally, logistic regression
analyses revealed that institutional factors, principally access
to credit, extension contacts, and farmer education level, significantly
influenced the adoption of bread wheat production technologies.
Effects of soil waterlogging on the concentration and uptake of selected nutrients by wheat genotypes differing in tolerance. [p. 45]
Amsal Tarekegne, A.T.P. Bennie, and M.T. Labuschagne.
Waterlogging of soil may restrict crop performance by altering soil mineral nutrient availability to and uptake by roots. A greenhouse experiment was conducted in 1998-99 using a soil high in clay content (Vertisol), at the University of the Orange Free State, South Africa, to determine the effects of soil waterlogging on Cu, Zn, P, and K nutrient concentration and uptake by wheat genotypes that differ in tolerance to waterlogging. Differential response of wheat genotypes to waterlogging treatments was observed on vegetative dry biomass and straw and grain yields. Root zone oxygenation was significantly depressed by the waterlogging treatments as indicated by significantly reduced soil redox potentials. Both waterlogging and genotype treatments significantly affected the uptake and concentration of most of the nutrients in the vegetative biomass at anthesis or in the straw and grain at maturity. A significant differential response of wheat genotypes to the waterlogging treatments was detected for most nutrient concentration and uptake parameters. Compared to waterlogging-tolerant genotypes, sensitive genotypes appeared to accumulate less Cu, Zn, P, and K. A considerable difference between waterlogging-sensitive and tolerant wheat genotypes was reflected in the accumulation and uptake of these nutrients under waterlogging stress. Therefore, the damaging effects of waterlogging were attributed to decreased nutrient uptake due to O2 deficiency in the root zone, in particular resulting in P and Zn deficiency. Selection of genotypes with enhanced ability to overcome the waterlogging-induced nutrient deficiency, particularly P and Zn deficiency, should improve wheat productivity in waterlogged soils.
Field response of bread wheat genotypes to Septoria tritici blotch. [p. 45]
Temesgen Kebede, Temam Hussien, and T.S. Payne.
A field experiment evaluated some bread wheat genotypes for resistance to S. tritici blotch. Thirty-six bread wheat genotypes were evaluated at the Bekoji and Holetta Agricultural Research Centers. The combined analysis of variance showed that the mean squares due to genotypes, environments, and their interaction were significant (P < 0.01) for percentage of necrotic leaf area. Mean separation of the percentage necrotic leaf area showed that advanced lines HAR 3640, HAR 3638, HAR 1698, HAR 2096, HAR 3641, and the commercial cultivar Mitike were resistant to S. tritici blotch as compared to a susceptible check. A significant negative correlation was found between disease severity and days to heading and plant height. A resistance parameter, deviation from the regression of infection on days to heading and height, was defined by eliminating the linear effects of escape mechanisms through late heading or tall stature. Using this resistance parameter, the advanced lines mentioned above were found to have true genetic resistance with the exception of HAR 3640. The resistance observed under field conditions for this line was due to an escape mechanism. This study suggested that in screening germ plasm for resistance to S. tritici blotch, the severity data must be corrected for the effect of days to heading and plant height, especially when the genotypes are not grouped into maturity classes.
Stability of stem rust resistance in some Ethiopian durum wheat varieties. [p. 45]
Sewalem Amogne, Woubit Dawit, and Yeshi Andenow.
In the central highlands of Ethiopia, durum wheat and stem rust have coevolved for thousands of years resulting in a wide virulence spectrum of the stem rust fungus. Races of the pathogen in the region are among the most virulent in the world, and the Debre Zeit area is known to represent the widest virulence spectrum in the country. Five durum wheat cultivars, Gerardo, Cocorit-71, Foka, Boohai, and DZ-04-118, were studied from 1993-94 to 1999-00 at Debre Zeit to determine the stability of their resistance to stem rust. Genotypic variance (S2i) and coefficient of variation (CVi were suitable for measuring the stability of disease resistance over time and were used in this investigation. Foka and Boohai were found to be more stable in their resistance to stem rust than the other cultivars tested. Foka and Boohai had smaller S^2^i 0.146 and 0.154, respectively; and relatively lower CVi values of 27.30 and 30.62, respectively. Gerardo was the least stable cultivar in terms of resistance to stem rust.
A study of the host range of wheat stem rust in Ethiopia. [p. 46]
Zerihun Kassaye and O.S. Abdalla.
Surveys were conducted to identify the host range of stem rust of wheat in the fields of state farms, small-scale farms, and research stations in the Arsi, Bale and the eastern and western Shewa regions of Ethiopia during the main and off-seasons of 1997-98. Seedlings of susceptible wheat varieties were inoculated with uredospores collected from weeds and vice versa. Out of 10 rust-infected weed species, Lolium temulentum and Setaria pumila were identified to be secondary hosts for wheat stem rust, whereas leaves of Avena fatua, Snowdenia polystachya, Cynodon dactylon, Bromus pectinatus, and Euphorbia shiperiana turned yellow but did not sporulate. Wheat sown in the off-season and volunteer wheat in fallow lands along the edges of crop fields, roads, irrigation canals, and under orchards were found to be good sources of stem rust infection.
Bread wheat yield stability and environmental clustering of major wheat growing zones in Ethiopia. [p. 46]
Debebe Masresha, Desalegn Debelo, Bedada Girma, Solomon Gelalcha, and Balcha Yaie.
A replicated yield trial comprising 18 genotypes and two checks was conducted at 14 locations for two consecutive years (199798). The testing locations were evenly distributed across the major wheat growing zones of Ethiopia and were characterized by different biotic and abiotic stresses. The combined data were subjected to statistical analysis to determine the pattern of adaptation of the test genotypes and to cluster the wheat growing zones on the basis of yield potential and limitations. The genotypes were grouped into widely, specifically, and generally adapted types. HAR 2536 was found to have wide adaptation, whereas HAR 2192 was specifically adapted to high rainfall areas owing to its long duration growth habit. The testing sites were broadly clustered into high-yielding and low-yielding types within different interactions. The environmental clusters followed altitude classes and rainfall amount and duration. This investigation elucidated that wheat productivity is more affected by moisture amount. Thus, variety selection for different moisture regimes plays an important role to maximize the productivity of rain-fed wheat production in Ethiopia.
Farmer participatory evaluation of bread wheat varieties and its impact on adoption of technology in West Shewa Zone of Ethiopia. [p. 46]
Kassa Getu, Kassahun Zewdie, Amsal Tarekegne, and Girma Taye.
Eight spring bread wheat varieties were evaluated at Guder in 1997 and 1998 to assess their adaptation to the area and to document farmers' preferences. During evaluation of the varieties by farmers and researchers, two quantitative (grain and biomass yield) and five qualitative (grain size, taste of bread, threshing ability, seed color, and baking quality) parameters were considered. Combined analyses of variance revealed that Galama yielded significantly higher than the local check, Dashen. Although statistically not significant, Kubsa and Mitike outyielded Dashen by 4.2 and 0.4 %, respectively. In terms of biomass yield, none of the improved varieties differed significantly from the local check . Results of the weighted direct matrix ranking indicated that Galama is the variety favored by farmers followed by Kubsa. Demonstration of Galama was started during 1998 on 47 farmers' fields. A follow-up study found that over 200 farmers were growing Galama during 1999. Farmer-based seed production and distribution played a major role in disseminating this variety. This paper, therefore, emphasizes the need to consider farmer participation to facilitate technology adoption by stakeholders.
Quality of Ethiopian durum wheat cultivars. [p. 47]
Efrem Bechere, R.J. Peña, and Demissie Mitiku.
Eleven cultivars of durum wheat were evaluated across five environments in Ethiopia for 1,000-kernel weight, protein concentration, gluten strength, mixing time, mixing height, color, and yellow berry. Gluten strength was measured by the SDS-sedimentation test. An electrophoretic study of gliadin and glutenin proteins was undertaken to investigate possible associations between these proteins and gluten strength. Significant differences between the genotypes were observed for 1,000-kernel weight, protein content, SDS-sedimentation volume, yellowness, and yellow berry. Six different patterns were identified for HMW-glutenin subunits with the combination null and 20 being the most common. For Glu-B1, the alleles producing protein subunits 20 and 7+8 were the most common. Less frequent was the one producing 6+8. Three cultivars had pattern LMW-1 and the remaining eight cultivars had pattern LMW-2. The strongest gluten strength corresponds to the mixed subunits 7+8/6+8 and 7+8/20, followed by subunits 6+8 and 7+8. Subunit 20 was associated with the lowest gluten strength. LMW-2 was strongly associated with higher gluten strength as compared to LMW-1. The effects of LMW- and HMW-glutenin subunits were additive. In order to develop high quality durum wheats, it would be useful to discard lines with LMW-1 and HMW glutenin subunit 20 and to combine electrophoretic analysis with SDS-sedimentation test.
Milling and baking qualities of some Ethiopian bread wheat varieties. [p. 47]
Solomon Gelalcha, Desalegn Debelo, Bedada Girma, T.S. Payne, Zewdie Alemayehu, and Balcha Yaie.
Information on physical and chemical quality parameters are necessary to assess the suitability of wheat varieties for different industrial uses. During 1998, 10 recommended bread wheat varieties were tested with and without fertilizer at three locations in Arsi Zone of Ethiopia, representing well-drained highland and medium altitude sites and a waterlogged Vertisol. The varieties were subjected to laboratory analysis for milling and baking quality parameters FLY, FPC, MDT, LFV, HLM, and TKM. Statistically significant differences were observed among the varieties for all characters studied. There were also significant differences due to applied fertilizer for flour yield, test weight, kernel weight and grain yield. Fertilizer by variety interaction significantly affected only flour protein content. Flour protein content was highly and positively correlated with test weight, grain size, flour yield, and dough development time. Flour yield was positively correlated with test weight and grain size. Varieties such as Dashen, Galama, Megal, and Abola exhibited good baking quality due to high quality gluten and high water absorption capacity. The other test varieties tended to be more suitable for biscuit making.
Identification of Ethiopian wheat cultivars by storage protein electrophoresis. [p. 47]
Amsal Tarekegne, M.T. Labuschagne, and H. Maartens.
Wheat cultivar identification is an increasingly important
component of genetic improvement, germ plasm management, protection
of breeders' rights, quality control and grain marketing. Protein
composition is a useful indicator of the genetic identity of a
genotype because protein synthesis is under direct genetic control.
Single seeds of Ethiopian-grown seedlots of 15 bread and 10 durum
wheat cultivars and lines were identified on the basis of gliadin,
HMW- and LMW-glutenin subunit banding patterns separated by SDS-PAGE.
The HMW-glutenin subunit banding, although simple and straightforward,
failed to distinguish cultivars adequately. The gliadin and LMW-glutenin
subunit banding patterns were unique for all cultivars and lines
studied, and hence were able to distinguish adequately among the
wheat cultivars studied. Therefore, we suggest that electrophoresis
of seed storage proteins can be of great importance in wheat cultivar
development, germ plasm management, seed certification, quality
control, and registration of new varietal releases.
ADET RESEARCH CENTER
Bahar Dar, Ethiopia.
Farmer participatory evaluation of promising bread wheat production technologies in northwestern Ethiopia. [p. 48]
Aklilu Agidie, D.G. Tanner, Tadesse Dessalegne, Minale Liben, and Akalu Teshome.
Three promising bread wheat genotypes were compared with two released check varieties by farmers' research groups using both researcher and farmer-selected crop management practices. Agronomic and economic data and farmers' assessment criteria were collected during the conduct of the trials on four host farmers' fields during 1999. The statistical analysis across the four sites indicated that there were significant grain yield differences due to genotype and crop management level. However, interactions between genotype by site and genotype by management level were nonsignificant. Mean grain yields for the farmer- and researcher-managed plots were 1,802 and 2,148 kg/ha, respectively. One advanced line, HAR-2258, was high yielding and preferred by farmers on the basis of its crop stand, spike size, disease resistance, maturity class, and crop uniformity. HAR-2258 and the check variety Abolla were both preferred by farmers for their quality in making staple food products. The improved crop management package for bread wheat was highly profitable for peasant farmers in NW Ethiopia, the researcher-managed production package increased wheat grain yields by an average of 19 % across the four locations, and exhibited a marginal rate of return of 210 % in comparison with the farmer-managed production practices.
Sources of variation for grain yield performance of bread wheat in northwestern Ethiopia. [p. 48]
Tadesse Dessalegn, Bedada Girma, T.S. Payne, C.S. van Deventer and M.T. Labuschagne.
Precise genotypic yield estimates from data of regional variety trials will increase the probability of successful selection. Additive main effects and multiplicative interaction (AMMI) analysis helps to understand sources of variation, to interpret the genotype by environment interaction, and to improve the probability of successful selection. A regional variety trial conducted in 12 environments was subjected to AMMI analysis to reveal the sources of grain yield variations and interaction. Environment and genotypes were highly significant but their interaction was nonsignificant. The environment sum of squares (SS) dominated the analysis even though the interaction SS was larger than genotypic SS. AMMI partitioned the interaction SS into six Interaction Principal Component Axes (IPCAs) with two of them significant; the AMMI biplot described different patterns of interactions. The contribution of environment was 86.4 %, indicating differences in environments (i.e., genotype yields ranged from 6,205 kg/ha at Adet to 1,643 kg/ha at Injibara, as Injibara is the lowest potential area for wheat production). Genotypes contributed 5.7 % of the variation and the difference between them was significant. Genotypes such as HAR1868, HAR1865, and HAR2096 were consistently high yielding varieties across environments with mean yields of 4,105, 3,932, and 3,786 kg/ha, respectively. They had positive interaction with high yielding locations (Adet, Motta, Fenoteselam, and Dabat) indicating their adaptation to these locations. The above locations showed consistency of main effects and interactions across years (i.e., the environments were suitable to discriminate this set of genotypes). Therefore, the result indicated consistency of ranking of genotypes (i.e., the top yielding in the top four ranks in both AMMI predicted and observed yields) that facilitates the use of mean yields as a selection criterion for variety recommendations. As a result, HAR1868 (Shina) was recommended for production in 1998 and HAR2096 was verified for release in 1999.
UNIVERSITY OF AGRICULTURE
P.O. Box 138, Dire Dawa, Ethiopia.
Germ plasm enhancement through wide hybridization and molecular breeding. [p. 49]
Harjit Singh, H.S. Dhaliwal, and Yifru Teklu.
Wild relatives of wheat are a rich source of novel variability for disease resistance, quality, and other traits of economic importance. Evaluating and cataloging 1,000 accessions of wild Triticum and Aegilops species identified a number of new sources of resistance to leaf rust, stripe rust, powdery mildew, loose smut, leaf spots, and cereal cyst nematode. Studies of HMW-glutenin subunit composition by SDS-PAGE revealed large intraspecific diversity in the wild species and identified novel Ax and Ay subunits at the Glu-A1 locus. Interspecific crossing of resistant accessions of three wild Triticum species with susceptible T. turgidum subsp. durum lines, followed by backcrossing to the cultivated species, resulted in the transfer of leaf rust resistance from six diverse accessions of T. timopheevii subsp. armeniacum; stripe rust resistance from one accession of T. urartu, two accessions of T. timopheevii subsp. armeniacum and one accession of T. turgidum subsp. dicoccoides; and powdery mildew resistance from two accessions of T. timopheevii subsp. armeniacum. Transfer of novel Ax and Ay subunits from T. urartu, T. monococcum subsp. aegilopoides, T. turgidum subsp. dicoccoides, and T. timopheevii subsp. armeniacum resulted in significant increase in gluten strength indicated by increases in SDS-sedimentation value from 37-40 for T. turgidum subsp. durum to 48-75 for the derivatives. Nonprogenitor Aegilops species with C, U, and M genomes have been found to be excellent sources of resistance to leaf rust and stripe rust. Rust-resistant, interspecific derivatives with alien chromosome substitution, addition, or translations from Ae. geniculata and Ae. triuncialis have been identified using the C-banding and genomic in situ hybridization techniques. Studies showed that the inhibitor of the Ph locus (PhI) from Ae. speltoides, now available in the background of Chinese Spring wheat, is useful to induce homoeologous pairing of alien chromosomes with wheat chromosomes in interspecific crosses. Induced homoeologous pairing coupled with C-banding and genomic in situ hybridization is useful to transfer small alien segments with desirable genes reducing linkage drag. A molecular linkage map has been constructed for the diploid cultivated species T. monococcum, a good source of resistance to diseases, insect pests, and herbicides. Molecular markers linked to protein content and seed size also have been identified. In our prebreeding program to improve two spring wheat cultivars, novel genes for disease resistance, high protein content, bread-making quality, and other agronomically important traits have been transferred from various genetic stocks. The improved durum and bread wheat materials, particularly those with rust resistance and processing quality, seem to have great potential for deployment in East Africa, including Ethiopia.
Performance of four new leaf rust-resistance genes transferred to common wheat from Ae. tauschii and T. monococcum. [p. 49]
The diploid progenitors of hexaploid common wheat, Ae. tauschii and T. monococcum, are valuable sources of genes for resistance to the leaf rust fungus. In this study, four new leaf rust-resistance genes previously transferred from these species to common wheat were considered. The gene Lr43, found in the wheat line KS92WGRC16, was transferred from Ae. tauschii. One gene, found in the wheat line KS92WGRC23, was transferred from T. monococcum subsp. monococcum. The other two genes, in wheat lines KS93U3 and KS93UI80, were obtained from T. monococcum subsp. aegilopoides. The genes in KS92WGRC23 and KS92WGRC16 were resistant in both Kansas and Texas field tests. The gene in KS93U3 was moderately resistant in Kansas but moderately resistant to moderately susceptible in Texas. The gene in KS93Ul80 was moderately resistant in Kansas but moderately resistant to susceptible in Texas. Adult-plant tests conducted in the greenhouse using isolate CBBQ indicated that KS92WGRC23, KS92WGRC16, and KS93UI80 were highly resistant, but KS93U3 had a moderately resistant reaction. Typical seedling ITs produced by these lines were zero (0), fleck (;), fleck associated with chlorosis (;C), and heterogeneous (X-). Results of growth chamber studies in different environments (12, 16, 20, and 24°C) showed slight temperature effects on the expression of KS93UI80, but not the other genes. The genes in the four lines should be used in combination with other resistance genes to prolong their usefulness.