Debre Zeit Agricultural Research Center Research Articles

Character Association and Path Coefficient Analysis of Morphological Quantitative Traits in Ethiopian Kale (Brassica Carinata A.)

The present study was conducted at Debre zeit Agricultural Research Center to determine the extent of association among yield and its related traits of 49 accessions and to assess the direct and indirect effects of yield component traits on leaf yield of Ethiopian Kale. The accession were studied for fourteen quantitative traits using 7 × 7 simple lattice design in 2018 cropping season. The accessions were collected from diverse agro ecological area. The research findings indicated that leaf yield per plant exhibited positive and significant phenotypic and genotypic association with all factors except for leaf width and leaf petiole thickness. The result revealed that days to first leaf picking, leaf fresh weight per plant, leaf dry matter content and number of leaves per plant were the most important yield components as they exerted positive direct effect on leaf yield as well as positive genotypic and phenotypic association with each other explaining the existence of significant association. This highlighting their importance in improving Ethiopian kale yield.

Morphological characterization of shallot (Allium cepa L. var. aggregatum) segregating populations obtained from natural-outcrossing in Ethiopial-outcrossing in Ethiopia

Shallot is a vegetable and condiment crop widely used in Ethiopia and globally. However, absence of improved and adaptable varieties has been the major cause of low productivity. Narrow genetic base of local shallot germplasm owing to vegetative reproduction of the crop, among others, has been the root cause of low productivity. Nevertheless, some plants within the germplasm were observed bolting and producing viable seeds, presenting an opportunity for genetic diversification. Consequently, a germplasm enhancement program was initiated using these naturally outcrossing genotypes where about eighty-one genotypes were generated. The present study was thus undertaken with the objective of characterizing, classifying, and selecting the eighty-one genotypes for future breeding activities. The genotypes were planted in 9x9 simple lattice design with two replications at Debre Zeit Agricultural Research Center (Ethiopia) during the dry (irrigated) season of 2021. The genotypes were evaluated for fifteen growth, yield, and quality traits. Significant variations were observed among the genotypes in terms of bulb yield, bulb height and diameter, total soluble solids, bolting percentage, and bulb skin color. Bulb yield of the genotypes ranged from 31.33 t/ha in DZSHT-79-1A to 9.63 t//ha in DZSHT-45-1A-1. DZSHT-51-2 (207.93 g) was the highest yielder per plant whereas DZSHT-065-6/90 (74.51 g) was the lowest yielder. DZSHT-14-2-1/90 had the thickest bulb (44.69 mm) significantly thicker than twenty two genotypes which had bulb diameter ranging from 28.92 mm to 20.29 mm. DZSHT-81-1/90 was a genotype with the longest bulb height (52.33 mm) while DZSHT-147-1C was a genotype with the shortest bulb (33.12 mm). DZSHT-307-1/90 had the highest TSS (16.78°Brix) significantly differing from DZSHT-002/07 which had the lowest TSS (11.17 °Brix). Dry matter of the genotypes ranged from 12.00% to 22.79%. DZSHT-004/07, DZSHT-111-2-1, DZSHT-41-2B and DZSHT-72-2 had DM% greater than 20% which coupled with greater than 14 °Brix could make them suitable for dehydrated shallots. Among the 81 genotypes characterized 4 (4.9%), 7 (8.6%), 13 (16.1%), 28 (34.6%) and 29 (35.8%) were yellow, golden, light red, red and dark red in colour, respectively. Fifteen of the genotypes had at least 50% bolting plants whereas twenty nine of the genotypes had less than 25% bolting. The results revealed that seven principal components explained approximately 76% of the observed variation. Cluster analysis grouped the genotypes into seven clusters, with the majority falling into three clusters. The study successfully identified genotypes with diverse and important traits and availed both the genotypes and the information for future breeding programs. These genotypes could be used for the development of improved hybrid and open pollinated shallot varieties with higher yield, quality and pest resistance/tolerance attributes.

Determination of Optimal Balanced Fertilizer Rate and Irrigation Scheduling for Onion Under Vertisol Soil Type

Onion is one of vegetable crops grown under irrigation. In order to improve crop production and productivity irrigation is the only solution for contributing towards food security, self-sufficiency and export market.. The Experiment was conducted in Debre Zeit Agricultural Research Center with determination of optimal balanced fertilizer rate and irrigation scheduling for Onion under Vertisol soil type to determine the optimum rate of balanced fertilizers and irrigation intervals and identify the interactive effect of nutrient and moisture levels on yield and yield quality of onion.The experimental treatments had three irrigation intervals, viz., 80%MAD, 100%MAD and 120%MAD and three Fertilizer rates of application, viz., 100kgha -1 NPSB, 150kgha -1 NPSB and 200kgha -1 , and a control fertilizer rate of 100kgha -1 urea. The design of the experimental plot was split plot in RCBD arrangement. The experimental study result showed that Crop Growth and Physiology Parameters, Yield Parameters and Water productivity had no significance difference under blended fertilizer rate application. But in irrigation intervals plant height, marketable yield and total bulb yield of onion was significantly affected. The highest total bulb yield of onion was recorded on the control irrigation (100% MAD) of the interval. Keywords: Blended fertilizer, Onion, Manageable Allowable Depletion (MAD), Irrigation Scheduling. DOI: 10.7176/JNSR/14-4-02 Publication date: February 28 th 2023

EVALUATION OF RELEASED TEF (ERAGROSTIS TEF [ZUCC.] TROTTER) VARIETIES AT SOUTHWESTERN PART OF ETHIOPIA

Objective: The objective of the study was to evaluate performance and identify high yielding and stable variety for southwestern part Ethiopia and recommend identified varieties for large scale production. Experimental Materials: Eight nationally released tef varieties were included in the study. The materials were obtained from Debre Zeit Agricultural Research Center (DZARC). Design and Trial Management: The experiment was conducted during the 2019 main cropping season at six locations, namely: Melko, Gechi, Omonada, Kersa, Mana, and Gooma weredas of Southwestern Ethiopia. The trial was conducted using randomized complete block design with three replications at all locations under rain-fed conditions. Sowing was done manually. Spacing between plots was 1 m, whereas that between replications was 1.5 m and the total plot size was 2 m × 2 m. Seed rates were based on the recommendation which was 15 kg/ha. Result and Discussion: Analysis of variance revealed the presence of significant (P < 0.05) differences among eight tef varieties of traits of days to heading, days to maturity, plant height, panicle length, lodging index, above ground biomass, and grain yield across locations. This indicated the presence of performance variation among the tested varieties for grain yield and it is possible to identify high yielder varieties for possible use in these locations. Conclusion and Recommendation: In general, varieties Dagim and Kora were high yielding and stable across locations and variety Gibe, Tesfa, and Negus were stable and low yielders across locations. The high yielding and stable varieties were recommendable for large scale production in southwestern part of Ethiopia. The experiment used data collected for only one season, which may limit the strength of its recommendation. However, the results are crucial in directing the breeding decision following additional season evaluation of the varieties in the same locations.

Genetic characterization and genome-wide association mapping for stem rust resistance in spring bread wheat

BackgroundEmerging wheat stem rust races have become a major threat to global wheat production. Finding additional loci responsible for resistance to these races and incorporating them into currently cultivated varieties is the most economic and environmentally sound strategy to combat this problem. Thus, this study was aimed at characterizing the genetic diversity and identifying the genetic loci conferring resistance to the stem rust of wheat. To accomplish this, 245 elite lines introduced from the International Center for Agricultural Research in the Dry Areas (ICARDA) were evaluated under natural stem rust pressure in the field at the Debre Zeit Agricultural Research Center, Ethiopia. The single nucleotide polymorphisms (SNP) marker data was retrieved from a 15 K SNP wheat array. A mixed linear model was used to investigate the association between SNP markers and the best linear unbiased prediction (BLUP) values of the stem rust coefficient of infection (CI).ResultsPhenotypic analysis revealed that 46% of the lines had a coefficient of infection (CI) in a range of 0 to 19. Genome-wide average values of 0.38, 0.20, and 0.71 were recorded for Nei’s gene diversity, polymorphism information content, and major allele frequency, respectively. A total of 46 marker-trait associations (MTAs) encompassed within eleven quantitative trait loci (QTL) were detected on chromosomes 1B, 3A, 3B, 4A, 4B, and 5A for CI. Two major QTLs with –log10 (p) ≥ 4 (EWYP1B.1 and EWYP1B.2) were discovered on chromosome 1B.ConclusionsThis study identified several novel markers associated with stem rust resistance in wheat with the potential to facilitate durable rust resistance development through marker-assisted selection. It is recommended that the resistant wheat genotypes identified in this study be used in the national wheat breeding programs to improve stem rust resistance.

Correlation and Path Coefficient Analysis in Seed Yield and Yield Related Traits Black Cumin (Nigella sativa L.) Genotypes, at Debre-Zeit, Central Ethiopia

Black cumin (Nigella sativa L.) is spice which are used as herbal medicine. To study correlation and path coefficient analysis for seed yield and oil content by using 5x5 simple lattice design for 25 black cumin genotypes at Debre-Zeit Agricultural Research Center during 2018/19 cropping season. For this evolution to used 12 characters seed yield and yield related traits. Number of primary branches per plant, secondary branches per plant, number of capsules per plant thousand seed weight, plant height, and number of seeds per capsule are positive and significant correlation with seed yield at both genotypic and phenotypic levels. Seed yield had also significant phenotypic correlation with oleoresin content of seeds. In path coefficient analysis number of primary and secondary branches per plant, number of capsules per plant and number of seeds per capsule plant height, had showed positive direct effects on seed yields at genotypic level. Then again thousand seed weight, plant height, number of seeds per capsule, number of capsule and number of seed per capsulehad positive direct effect on seed yield at phenotypic level.This study showed that Correlation studies provide a better understanding of yield components with seed yield helps the plant breeder during selection in black cumin genotypes. Keywords : Black cumin ,Correlation , path coefficient, Genotypes, phenotypes DOI: 10.7176/JBAH/12-2-02 Publication date: January 31 st 2022

Comparative Study on Major and Trace Mineral Content of Edible and Eggshell Powders from Ethiopian Local and Exotic Breed Chicken Eggs

In this study, the effect on the mineral content of eggs from local and exotic breed hens was investigated. For this study, random samples were collected from the Ethiopian Institute of Agricultural Research, Debrezeit Agricultural Research Center, and Fresh Corner Poultry Farming Debrezeite, Ethiopia for the exotic and local breed eggs respectively. Eggshells and edible portion of the egg were analyzed for Calcium (Ca), Potassium (K), Phosphors (P), Sodium (Na), Magnesium (Mg), Iron (Fe), Zinc (Zn), Manganese (Mn), and Copper (Cu) contents. The Phosphors and Zinc contents of the edible egg portion were higher in the local breed eggs than in exotic breed eggs. Calcium and Magnesium content of the eggshell was higher in local breed eggs while Zn content showed a marked decrease. As far as Potassium, Magnesium, Sodium Phosphors, and Copper values were concerned, these did not differ between the eggs from local and exotic breed types. The present finding provides sizeable differences in mineral content between the eggs from the local and exotic breed hens. The results afford a point of departure measurements of major and trace mineral contents of eggs and suggest quantifiable differences amid eggs from hens in different husbandry systems, and hens breed types. The physiological significance of those differences is discussed. But, future studies should elucidate differences observed by crossbreed types, diet effect, and husbandry system. Drying eggs can be a workable food systems intervention that can mend the wellbeing and eminence of diets in low-income countries like Ethiopia. Keywords: Egg, Hen, Mineral Content, Local breed, Exotic breed, Food System, Low-income DOI: 10.7176/CPER/64-01 Publication date: January 31 st 2022

AMMI BIPLOT ANALYSIS OF GRAIN YIELD PERFORMANCES OF TEF (ERAGROSTIS TEF [ZUCC.] TROTTER) VARIETIES ACROSS DIFFERENT LOCATIONS OF SOUTH AND SOUTHWESTERN ETHIOPIA

Objective: The objective of the study was to identify high yielding and stable tef varieties across different locations of South and Southwestern part of Ethiopia.
 Methods: The experiment was conducted using 21 tef varieties obtained from a tef breeding program based at Debre Zeit Agricultural Research Center. The trial was laid out using a randomized complete block design with three replications at six locations during the 2018 cropping season. Data for all relevant agronomic traits were collected, but only plot yield data converted to kg/ha was subjected to statistical analysis.
 Results: The results of combined analysis of variance for grain yield of 21 tef varieties across six locations revealed that there is a highly significant difference among the locations, genotypes, and interaction effects with the contributions of 67.4, 8.1, and 17.8% of sum of squares, respectively. Analysis of variance of AMMI model revealed the two interaction principal component analysis (IPCA1 and IPCA2) were highly significant according to Gollob’s test and accounted for 42.8 and 20.6% of variance, respectively.
 Conclusion: Based on AMMI Biplot analysis, Ambo location could be the representative area among tested locations to determine the tef varieties and the variety Heber-1 (G11) and Dukem (G15) were recommendable for broad adaptation since they were stable and high yielding across locations.

Optimal Irrigation Scheduling of Garlic (Allium sativum L.) using Allowable Soil Moisture Depletion for Water Scarce Areas of Ethiopia

The main objective of this study was to evaluate the responses of garlic to the irrigation regime (when and how much) to irrigate. The field experiment was conducted at the main station of Debre Zeit Agricultural Research Center in 2016 and 2017. Five treatments for allowable soil moisture depletion levels (ASMDL) of irrigation at 60%, 80%, 100%, 120%, and 140% were used. Application of irrigation water for garlic was scheduled when 30% of the total water available in the soil profile was depleted. Treatments’ were laid out in RCBD experimental design with three replications for each treatment. In the study, it was observed that there was a significant difference in marketable yield and water use efficiency (WUE) between treatments. The maximum marketable bulb yield (7.5 t/ha) and WUE were observed by applying irrigation water at 20% more than the recommended ASMDL and the lowest (4.68 t/ha) was recorded at 40% less than the recommended ASMDL. Reducing the allowable soil moisture depletion level by 40% and also by 20% from the recommended fraction (0.30) has significantly increased the water use efficiency. Generally, from this study it has been observed that irrigating garlic at a shorter frequency enhance yield and water productivity. Therefore, managing the soil moisture content above the allowable depletion level (i.e 60% ASMDL and 80% ASMDL) was better than using the recommended allowable depletion and the other lower levels. Hence, to have a higher yield and maximum water productivity, it was recommended to irrigate garlic frequently.

Regulated Deficit Irrigation and Onion (Allium cepa L.) Yield Response on Water Productivity

Irrigation is the only solution to improve crop production and productivity thereby contributing towards food security, self-sufficiency and export market. The efficient use of water by irrigation system is becoming increasingly important in arid and semi-arid regions with limited water resources. The Experiment was conducted in Debre Zeit Agricultural Research Center with the Regulated Deficit Irrigation and Onion (Allium cepa L.) Yield Response on Water Productivity in Ethiopia during 2017/2018 cropping season. The objective of the experiment was identify the pin point of water stress threshold value of onion under deficit irrigation and investigate the effect of alternate, fixed and conventional furrow irrigation methods on crop yield and water productivity under deficit irrigation. The experimental treatments had three furrow irrigation methods, (alternate furrow irrigation (AFI), fixed furrow irrigation (FFI) and conventional furrow irrigation (CFI)) and two deficit irrigation levels of application, viz., 85 % ETc, and70 % ETc and a control irrigation of 100%ETc. The design of the experimental plot was split plot in RCBD arrangement and replicated three times. The three furrow irrigation methods were arranged as main plots and the deficit levels as sub plots a total of nine (9) treatment combinations. All collected data, were statistically analyzed using SAS 9.1 statistical software. The experimental study result showed that bulb diameter, unmarketable bulb yield and total bulb yield of onion were highly significance difference (p<0.001) both in furrow irrigation methods and irrigation levels. Likewise diameter of onion also gave highest on CFI and 100%ETc irrigation water application level which is 6.69cm and 6.94cm respectively. According to the results obtained, the highest total yield was recorded for the treatment of 100%ETc irrigation water application and AFI of the furrow irrigation method 38947kgha -1 and 35920kgha -1 respectively however, the lowest total bulb yield of 30253kg ha -1 and 29135kg ha -1 were recorded when FFI system was applied and in 70%ETc of water applied. Bulb height of onion was highly significance difference (p<0.001) only on deficit irrigation levels. On the other hand, marketable bulb yield, irrigation water use efficiency and crop water use efficiency were significance difference (P ≤ 0.05) by the interaction of furrow irrigation methods and deficit irrigation levels. The highest average marketable bulb yield of onion was obtained 42219kgha -1 on CFI with the combination of 100%ETc irrigation level in addition to this IWUE and CWUE both are recorded highest result on 70%ETc and AFI furrow irrigation method. Generally, among all irrigation treatments 70%ETc deficit irrigation level applied under AFI method was efficient in conserving significant irrigation water. Therefore, it could be concluded that, AFI can save a substantial amount of water and labor without highly reduction of onion yield and the lowest CWUE and IWUE was gave FFI followed by CFI. Keywords: Alternate furrow irrigation, Conventional furrow irrigation, Deficit irrigation, fixed furrow irrigation, Onion DOI: 10.7176/JRDM/71-02 Publication date: November 30 th 2020

Pattern of egg distribution by Adzuki bean beetle, Callosobruchus chinensis (L.) (Coleoptera: Chysomelidae) in stored chickpea under natural infestation

Under laboratory experimental condition female Adzuki bean beetles, Callosobruchus chinensis (L.) are known to evenly distribute their eggs over grains available for egg laying. However, currently there are no data on pattern of egg distribution by Adzuki bean beetle in large quantity of chickpea grain stored for extended period of time. The objective of this study was to determine the number and distribution of eggs among grains of chickpea stored in large quantity for 8 months and subjected to natural infestations. The experiment was conducted under room temperature and relative humidity at Debre Zeit Agricultural Research Center. The chickpea cultivars used were Natoli (desi type, 22 g per 100 seeds with Tuberculated seed coat texture) and Arerti (kabuli type, 26 g per 100 seeds with smooth seed coat texture) and for each cultivar there were 21 replicas of bags (40 cm wide and 70 cm high). From each bag, which contains 10 kg each, 25 chickpea grain samples were randomly selected at monthly intervals and examined for the presence or absence of Adzuki bean beetle eggs. Grains with eggs were categorized into frequency classes (i.e. 0, 1, 2, …, n) based on the number of eggs present on them. The variance to mean ratio was used to decide the type of egg dispersion pattern. In all the sampling dates and on both cultivars, the variance to mean ratios were highly significantly greater than one indicating that egg distribution by female Adzuki bean beetles on grains of chickpea was aggregated type. Moreover, further analysis of data had shown that the egg distribution pattern perfectly fits the negative binomial distribution, which confirms that the pattern of egg distribution on chickpea grains was aggregated/clumped type.

Population dynamics of cabbage aphid, Brevicoryne brassicae L. (Homoptera: Aphididae) in relation to weather factors on major brassica crops in central rift valley of Ethiopia: baseline studies for the management of the pest

Cabbage aphid, Brevicoryne brassicae L. is a major pest of cruciferous crops all over the world. The population dynamics of the pest is highly influenced by weather factors. A field study was carried out in 2018/19 at Debre Zeit Agricultural Research Center (DZARC) to determine the role of weather factors on cabbage aphid population dynamics. Four brassica crops namely Ethiopian Kale, head Cabbage, Cauliflower and Broccoli were planted on two different dates at fifteen days interval. Results revealed that, maximum aphid population of 164.7 ± 2.93 and 70.2 ± 2.64 aphid/ inch2 leaf area were recorded on the date 15/12/2018, on late planted kale and head cabbage crops, respectively. The highest mean infestation for all tested crops (22.77aphids/inch2 leaf area) was observed on late planted crops as compared to 0.82 aphids/inch2 leaf area on early plantings. Accordingly, early planted crops were 96.4% safer than late planted crops for aphid infestations. Correlation analysis showed that, the maximum temperature had a significant influence on aphid population specifically on kale crop (r = 0.676, p = 0.032). Although, the relative humidity, minimum and average temperature, rainfall and wind speed has shown none significant correlation with aphid population growth. There was variation in aphid population, crop preference and infestation peak in relation to weather factors. In general, during the experiment higher aphid population was observed on kale crop when the maximum temperature and relative humidity were < 26.750C and 72%, respectively. This study provided information on time of initial infestation and also the peak activity of the particular insect in relation to temperature. Therefore, the population peak timing reported in this study (45th SMW) is useful as a critical infestation period for scheduling cabbage aphid management practices.

Genetic diversity in anchote (Coccinia abyssinica (Lam.) Cogn) using microsatellite markers

Anchote (Coccinia abyssinica (Lam.) Cogn) is an endemic crop species of Ethiopian origin mainly cultivated for its nutritious tuberous roots and tender leaves. The crop plays an important role in the local diet of rural and peri-urban communities mainly in Western and South Western Ethiopia. Limited molecular marker resources hinder breeding and genetic studies for improvement, conservation and management of anchote genetic resources. In this study we aimed to (i) measure the genetic diversity of C. abyssinica and of its populations; and (ii) describe the genetic structure of populations across the cultivation range in Ethiopia. A total of 45 germplasm accessions collected from Western parts of Ethiopia were studied along with three cultivars of related species in Cucurbitaceae family using 24 microsatellite markers. Results showed high level of genetic diversity in the anchote accessions. All the analyzed loci were highly polymorphic and detected a total of 354 alleles among all population, with an average of 15 alleles per locus. The average genetic diversity, as quantified by the expected heterozygosity, was 0.88 ± 0.06 per locus. Nei’s gene diversity index was the highest (I = 1.93) for populations from East Wellega maintained in situ in the farmers’ field and ex situ in Debre Zeit Agricultural Research Center (DZARC). Using discriminant analysis of principal components (DAPC), four clusters including outlier groups were detected. The DAPC analysis indicated that the most closely related populations geographically occurred in close proximity to each other. AMOVA attributed 95% of the genetic variation to within population and only 4% to between populations. The results provide important genetic information in C. abyssinica to drive improvement, management and conservation decisions efforts.

English

This study was conducted to evaluate the production and reproduction performance of chicken breed under semi-scavenging system of Seka Chekorsa and Omo Nada districts of Jimma Zone. A total of 800 day old chicks were obtained from Debre Zeit Agricultural Research center. 50 day old chicks were distributed with hay box brooder, and the experiment was arranged in a nested design. The result of the current study indicated that male chickens of both breeds in this study reached sexual maturity and slaughter weight within four months in both districts and mature body weights of 1831.25 and 1569.18 g at Seka and 1615.00 and 1586.25g in Omo Nada, respectively for Lohmann dual and Dominant red barred. Although there was no statistically significant difference between the two breeds, Lohmann dual breeds attained age at first egg within 148 days and Dominant red barred (162.25 days) breeds in Seka Chekorsa and 157.50 and 160.25 days, respectively for lohmann and Dominant red barred in Omo Nada district. In general, the current study indicated good performance of Lohmann dual breeds while it needs further study to conclude number of eggs per clutch, number of eggs per hen per year and hatchability for both breeds in both study districts. So this study might be good to consider in the future in other areas. Key words: Dual purpose breed, on farm evaluation, semi-scavenging, Omo Nada, Seka Chekorsa.

English

Leaf rust caused by the pathogen Puccinia triticina is one of the important diseases of wheat in Ethiopia; and yield loss due to this disease has reached up to 75%. A study was carried out to detect physiologic races of the pathogen from some parts of Bale, Gondar and Shewa and to identify seedling resistance of Ethiopian durum cultivars. Twenty-four mono pustule isolates were made, and out of those, only three P. triticina races namely; BBBB, BBBN and BBBQ were identified. Race BBBN was detected for the first time in Ethiopia and was less virulent to commercial durum wheat cultivars than BBBQ and BBBB, while phenotype BBBB was relatively highly virulent to Ethiopian durum wheat and it infect 42.5% of the tested cultivars and is not virulent to Thatcher and Thatcher isoline leaf rust differential cultivars. Thirty six commercial durum wheat cultivars and three land race cultivars were evaluated against those three leaf rust pathogen races at seedling stage in the green house at Debre-Zeit Agricultural Research Center. Varieties Utuba, Lelisa, Worer, Bekelcha, Tate, Filakit, Foka, Alem tena, Hitosa, Kilinto, Denbi, Ude, LD-357, Boohai, Mukuye, Robe, Mangudo and Assasa exhibited resistance reaction (; to 2) to all the three leaf rust races, while the rest showed susceptible at least to one of the race. All the three land race cultivars (Mcd4-12, Mcd4-32 and Mcd7-42) were susceptible to all pathogen races. Key words: Durum wheat, leaf rust, Puccinia triticina, race, seedling resistance.

Evaluation of Drought Tolerance in Tef [Eragrostis Tef (Zucc.) Trotter] Genotypes Using Drought Tolerance Indices

A field experiment was conducted to identify drought tolerant, high yielding and stable tef genotypes using drought tolerance indices. Sixty-four tef genotypes were evaluated under drought and non-stress conditions using “8 × 8 simple lattice design” with two replications at Debre-Zeit Agricultural Research Center. Drought tolerance indices including drought susceptibility index (SSI), drought tolerance index (STI), geometric mean productivity (GMP), mean productivity (MP), yield index (YI), yield stability index (YSI), drought resistance index (DRI), abiotic tolerance index (ATI), stress susceptibility percentage index (SSPI), harmonic mean (HM) were estimated from grain yield under drought (Ys) and non-stress (Yp) conditions. Highest grain yields in both drought and normal watering conditions were recorded for genotype Melko. Based on drought tolerant indices the highest values of STI, GMP, and MP were related to genotypes Melko, Etsub, and Ziquala. Correlation analysis revealed that grain yield was positively and significantly correlated with STI, GMP, MP, YI, DRI, and HM, indicating that these indices were more important for screening stress-tolerant tef genotypes. Principal component analysis indicated that the first two components accounted for more than 98% of the total variations. The first PC contributed for 67.9% of the variation with strong presence of STI, GMP, MP, YI, DRI, HM, Ys, and Yp. Biplot analysis also indicated the STI, GMP, MP, YI, DRI, and HM were more reliable indices to identify drought tolerant tef genotypes. Cluster analysis grouped the 64 tef genotypes into seven clusters. The study showed that selection based on indices which exhibited significant and positive coordination with Ys and Yp are more reliable parameters for breeders to use in the tef improvement program.

Seed rates and insecticides effects on Russian wheat aphid Diuraphis noxia (Hemiptera: Aphididae) occurrence in irrigated durum wheat (Triticum durum) in the central highland of Ethiopia

The Russian Wheat Aphid (RWA) Diuraphis noxia (Kurdjumov) causes severe damage to wheat in the highlands of Ethiopia. An experiment was conducted to evaluate the effect of seed rates and insecticides on incidence of RWA and grain yield of durum wheat under irrigated filed condition at Debre Zeit Agricultural Research Center, Ethiopia, during 2017. Three insecticides (Dimethoate 40 EC, Actellic 50 EC and Highpro220EW) and one untreated check with six seed rates (75,100,125, 150,175, and 200 kg/ha) were used in split plot design with three replications. Data were collected on plant or plot basis. Data on RWA number was recorded on plant bases. Whereas, leaf rolling, chlorosis, number of deformed head, phenological stages, yield and other yield related parameters were collected on plot basis. Data were subjected to analysis of variance using SAS version 9.3. Mean separation was made using least significant test using Tukey’s HSD (Honestly Significant Difference). The seed rates and insecticides significantly affected the incidence of RWA plant damage (chlorosis), deformed heads, plant height, yield and yield components except the interaction for number of grains per head and thousand seed weight. Dimethoate 40EC and Highpro 220EW sprayed plots gave the highest grain yield and the tallest plant height. The highest grain yield was obtained from 125 kg/ha sown plots and sprayed with Dimethoate 40 EC and the lowest grain yield was obtained from the untreated check sown at the rate of 75 kg/ha. The highest number of RWA per tiller and damaged plants were recorded on the untreated plots and the lowest RWA numbers was recorded, in decreasing order, from Dimethoate 40EC, Highpro 220EW and Actilic 50EC treated plots. Untreated plots with seed rate 150 kg/ha, 175 kg/ha and 200 kg/ha sown plots significantly reduced RWA population than the others. This indicates that there is the possibility of using seed rates above 150 kg/ha to managing RWA. RWA is a serious pest of irrigated wheat in Ethiopia, causing substantial yield losses in different seasons to in irrigated wheat production. The overall results indicated that sowing at a seed rates of 125 kg/ha and spraying Dimethoate 40EC gave the highest yield grain and can be recommended for RWA management under irrigated condition.

Planting Time Effects on the Productivity of Tef [&amp;lt;i&amp;gt;Eragrostis tef&amp;lt;/i&amp;gt; (Zucc.) Varieties in Ethiopia

In recent days there is change in trend of rainfall across the country where its starts in May and ceases early-to-mid September. This implies that adjusting cropping calendar is vital to adapt to the changing climate of the area. The field experiments were carried out at Debre Zeit Agricultural Research Center (DZARC) and Alemtena during the main cropping season from 2015 to 2017 to determine appropriate sowing date for tef varieties. The treatments consisted of three sowing date (early-July, mid-July, and late-July) and two recently released tef varieties (Kora and Boset). The experiment was laid out in a randomized complete block design in a factorial arrangement and replicated four times per treatment. Data were taken crop growth, biomass yield, and grain yield. Combined analysis of variance overs years showed that interaction effects of variety by sowing date were significant effects on plant height and panicle length at DZAR while, at Alemtena, plant height and panicle length was significantly affected only by variety. At both location biomass and grain yield of tef was significantly affected by variety and sowing date interaction. Among the different sowing date treatments, sowing of Kora variety in mid-July showed the highest mean biomass yield (8444.4 kg/ha and grain yield (1813.3 kg/ha) at DZARC but at Alemtena the highest biomass (9766.2 kg/ha) and grain yield (1595.7 kg/ha) was achieved Kora was sown in earl-July. However, sowing of Boset variety at mid-July was comparable yield advantages. Over all, based on the result of this study, sowing of mid-July and early-July would be recommended for the mentioned variety production at DZARC and Alemtena, respectively.

Optimizing Sowing Date for the Productivity of Durum Wheat (&amp;lt;i&amp;gt;Triticum turgidum&amp;lt;/i&amp;gt; L. var. Durum) in Central Highland of Ethiopia

The field experiments were carried out at Debre Zeit Agricultural Research Center during the main cropping season between 2015 and 2017 to determine best sowing date for durum wheat productivity. The treatments were consisted of a factorial combination of four sowing date (late-June, mid-July, Late-July and mid-August) and two durum wheat varieties (Ude and Mangudo). The experiment was laid out in a randomized complete block design with three replication. Results showed that the main effect of sowing date had a significant effect on growth, yield and yield components of durum wheat. In contrast, main effect of variety and interaction effects of variety with sowing date had not a significant effect on growth, yield and yield components of durum wheat. The highest aboveground biomass yield (8990.7 kg/ha) and grain yield (3504.6 kg/ha) were obtained when durum wheat was sown in mid-July, but it was not significantly different yield from late-June. Based on 30 years rainfall data, the possibility of occurrence of dry spell is less during this period. Therefore, sowing of durum wheat from late-June to mid-July can be recommended for durum wheat production in the study area.

Physiological Growth Indices of Durum Wheat (&amp;lt;i&amp;gt;Triticum turgidum&amp;lt;/i&amp;gt; L. Var. durum) as Affected by Rates of Blended and Nitrogen Fertilizers

In order to investigation the effects of blended NPSB and N fertilizer rates on physiological and growth indices in durum wheat, a randomized complete block design in a factorial arrangement and replicated 3 times per treatment was conducted in research field of Debre Zeit Agricultural Research Center in 2017 and 2018 under rain-fed condition. The treatments consisted of 4 levels of blended (0, 50, 100, and 150 kg NPSB ha^-1) and N (0, 46, 69 and 92 kg N ha^-1) fertilizers. The results revealed that leaf area index (LAI) at 64 days after sowing (DAS), crop growth rate (CGR) at 34-64 and 64-94 DAS, relative growth rate (RGR) at 34-64 DAS were significantly (P<0.05) affected by the interaction effects of blended NPSB and N fertilizers. Chlorophyll content (CHL), plant height (PH), days to heading (DH), and days to physiological maturity (DPM) were significantly influenced only by N levels. The highest LAI (4.50), CGR (4.37 g m^-2°Cdays^-1) at 34-64 DAS and (14.81g m^-2°Cdays^-1) at 64-94 DAS and RGR (0.0077 g g^-1°Cdays^-1) at 34-64 DAS were observed at combined application of 150 kg blended NPSB with 92 kg N ha^-1. The highest PH (89.4 cm), CHL (40.09), DH (60.92 days) and DPM (116.75 days) were noted in 92 kg N ha. On overall performance application of 150 kg NPSB with 92 kg N/ha levels showed better results on the growth and physiological traits of durum wheat as compared to other blended and N levels.