In spite of the importance of quality protein maize to alleviate protein deficiency, almost all maize varieties cultivated in Ethiopia are normal maize varieties, which are devoid of lysine and tryptophan. Perusing the combining ability of QPM inbred for grain yield and its components is vital to design appropriate breeding strategies for the development of nutritionally enhanced maize cultivars. A line x tester analysis involving 36 crosses generated by crossing 9 elite maize inbred lines with 4 testers were evaluated for different desirable agronomic traits during the 2019 main season at BNMRC and JARC. The experiment was conducted using alpha lattice design with 3 replications. The objectives were to determine the combining ability of quality protein maize inbred lines, adapted to mid altitude agroecology of Ethiopia for agronomic traits. The crosses were evaluated in alpha lattice design replicated 3 times. Analyses of variances showed significant mean squares due to crosses for almost all the traits studied. GCA mean squares due to lines and testers were significant (P<0.05 or P<0.01) for most studied traits. SCA mean squares were also significant for most attributes across locations. The comparative importance of GCA and SCA variances observed in the current study for most studied traits indicated the preponderance of additive genetic variance in governing these attributes. Only L3 was the best general combiner for grain yield. Inbred line L3, for days to anthesis and L5 for days to silking had negative and significant GCA effects. L5 and L6 displayed negative and significant GCA effects for plant and ear height. Crosses, L2xT4, L3xT4, L4xT4, L5xT2, L6xT3, L7xT2, L9xT1 and L9xT4 were good specific combiners for grain yield. In general, these genotypes help as a source of promising alleles that could be used for forthcoming breeding work in the development of quality protein maize cultivars with desirable traits.
Maize is one of the most important cereal crops used as source of food and feed. Identification of suitable maize inbred lines and testers for the development of stable maize hybrids can be challenging. The assessments of the combining ability of selected maize inbred lines and testers, agronomic performance and yield stability of the resultant topcross hybrids would provide useful information that would guide the breeding program for optimum yield. Nine yellow maize inbred lines and two open-pollinated varieties (Early LN-Y and TZE-31DMRSRLNSYN) were crossed in a line × tester mating scheme. The resultant eighteen topcross hybrids together with two commercial hybrids and two candidate hybrids as checks were evaluated across eight locations in Nigeria. Significant differences were detected among the genotypes, lines, testers, line × tester and their interactions with the environment for most traits studied. Four inbred lines (TZEEIOR-197, TZEI-13, TZEI-17 and TZEIORQ-44) had significant General Combining Ability (GCA) effects for grain yield (GY), whereas TZEIORQ-44, TZEI-8 and TZEI-17 had significant GCA effects for earliness. Five topcrosses (TZE-31DMRSRLNSYN × TZEEIOR-197, TZE-31DMRSRLNSYN × TZEI-129, Early LN-Y × TZEI-13, TZE-31DMRSRLNSYN × TZEI-17 and Early LN-Y × TZEI-8) had significant specific combining ability effects for GY. The best eight topcross hybrids had comparable GY with the commercial checks. Four each of the eight hybrids were of either tester. Based on the GGE-biplot, TZE-31DMRSRLNSYN × ENT 13 was the most stable genotype across the test environments. The inbred lines with significant GCA effects and superior testcrosses were identified for future breeding programs. Key words: Grain yield, inbred lines, line × tester, testers, topcross maize hybrids.
Genotype x Environment interactions and identification of stable genotypes in crop breeding programsfor the production of grain crops under rain fed environments have become challenging.The study aimed to identify high yielding and stable durum wheat genotypes that are best suited for the relatively long season, high rain fall wheat growing environment of Ethiopia.In the study a total of 51 durum wheat genotypes including three standard check varieties was evaluated at six locations representing the four major wheat growing zones of Ethiopia from 2020-2021.The grain yield data were analyzed using AMMI and GGE biplot stability models.The genotypes showed a wide range of variability based on their grain yield at different locations.The analysis of variance indicated highly significant differences on grain yield between genotypes lines, environment and their interaction.The G-25 DW193667 ranked best for (CD and KU) and G7 DW 184042(DZ and Adet) and G-1(Enwary) based on grain yield performance.Genotypes 7 DW 184042and 25 DW193667were identified as the most stable based on AMMI model and GGE biplot analysis.The GGE biplot indicated Debre-Zeit (E9) to be an ideal environment followed by Adet (E7) that could be recommended for future wheat program to wards identifying the most adapted genotypes.
Spider plant (Cleome gynandra L, Cleomaceae) is used in many parts of the world as an emergency crop, enabling populations to survive periods of hunger and famine.It is a leafy vegetable much appreciated by local populations, whose tender leaves and stems are used to prepare a variety of local dishes.The aim of this study was to gain insight into the perceptions and preferences of stakeholders in the C. gynandra L. (Cleomaceae) value chain in Burkina Faso.One hundred and twenty stakeholders from different socio-professional groups took part in the study.The scoring matrix method was used.This scoring system assigns scores on a scale from 0 to 5. A score of zero (0) is assigned if the genotype is not interesting, and a score of five (05) if the genotype is considered very interesting for the traits considered by the stakeholders.Notes 1, 2, 3 and 4, respectively for the least interesting to the most interesting genotypes.Six selection criteria were thus identified by the players in the value chain.These included plant height, number of primary branches, leaf biomass, low pubescence, leaf and twig tenderness, ease of cooking, less bitter taste and high market value.The OUA10, OUA9, KOM2 and MAN genotypes were preferred by all players in the value chain.Further breeding work based on these genotypes will eventually enable the extension of high-performance varieties for the benefit of local populations.
Fall armyworm (FAW) is currently the most destructive insect pest of maize in sub-Saharan Africa (SSA). Varieties that combine high grain yield (GY) with tolerance to FAW would enhance and stabilize maize productivity in SSA. Genotypes resistant to lepidopteran pests like stem borer (SB) could serve as potential sources of alleles for development of FAW resistant varieties. This study was conducted to assess some SB-resistant maize genotypes for FAW tolerance, and to identify genotypes that combined high GY with tolerance to FAW. Twenty-nine white maize genotypes with varying levels of SB resistance were evaluated under artificial FAW-infested and FAW-protected conditions using randomized complete block design with three replicates. Genotypic differences were significant for all the traits under both FAW-infested and FAW-protected conditions. Under FAW-infested condition, GY ranged from 3.44 (FAWTH-8) to 5.81 t ha -1 (FAWTH-1) (mean = 4.61 t ha -1 ), and from 3.42 (FAWTH-25) to 6.85 t ha -1 (FAWTH-18) (mean = 4 .86 t ha -1 ) under FAW-protected condition. Across genotypes, FAW infestation reduced GY by 5.1% suggesting that SB resistance could confer tolerance to FAW. Association of GY under FAW-infested condition with FAW Leaf Damage (FAWLD; r=-0.45) and FAW Ear Damage (FAWED; r=-0.65) were significant. Base index (BI) was significantly correlated with GY (r=0.93), ear aspect (r=- 0.84), FAWLD (r=-0.66) and FAWED (r=-0.78). Six moderately resistant genotypes (FAWTH-1, FAWTH-13, FAWTH-4, FAWTH-10, FAWTH-23 and FAWTH-6) with GY ≥ 5.13 t ha -1 and positive BI ≥ 4.0 were identified. The genotypes varied for FAW tolerance. Base index and low FAW damage scores could serve as selection criteria for combined tolerance to FAW and high GY. The identified genotypes are recommended for further development as FAW tolerant varieties.
Five tomato cultivars were studied for inheritance of bacterial wilt resistance. Lines AVTO1429, AVTO1424, and AVTO1314 have the resistance gene, Roma VF lacks the resistance gene, and Valoria Select is claimed to have resistance but has not been evaluated. The study, which was carried out in a split plot design, involved six generations and backcrosses that were conducted in a greenhouse and a field. Artificial inoculation of Ralstonia solanacearum was carried out in greenhouse. Parental lines AVTO1429, AVTO1424 and AVTO1314 had the lowest incidence of 37.78, 26.67 and 26.67%, respectively while Roma VF had the highest at 95%. F1 hybrids had lower incidence of ≤ 33.33% in all the crosses. Cross F1 x Parent 2 (BC2) had significantly lower disease incidence and severity compared to F2 hybrids, F1 x Parent 1 (BC1) and P1 (Roma VF) in all crosses. Computation of gene effects showed significant additive effects of 1.941 for cross Roma VF x AVTO1429 and 1.925 for cross Roma VF x Valoria select at p<0.01. Dominance effects, additive x additive, additive x dominance and dominance x dominance interaction in all the crosses were significantly different at p<0.01. The important gene effects for bacterial wilt resistance inheritance was in additive and dominance-additive portions which implied that the resistance trait was inherited. Key words: Ralstonia solanacearum, tomato, resistance trait, inheritance, bacterial wilt.
Nitrogen is essential due to its function in plant growth and development. It is a component of DNA and proteins which are the building blocks of life. Nitrogen is one of the most limiting factors for crop production. The need to meet the huge nitrogen requirement has necessitated the use of synthetic fertilizer. However, its continued application affects soil health, environment, and agricultural sustainability. Identifying breeding lines and developing new varieties that can efficiently fix atmospheric nitrogen and integrating these varieties into farming systems is one of the best alternatives. Field experiment was conducted at the Savanna Agricultural Research Institute research fields using 20 elite soybean lines under rain fed conditions. The objective was to select soybean (Glycine max) lines for improved nitrogen fixation, water use efficiency and grain yield. Randomized complete block design was used with three replications. Data collected were the amount of nitrogen fixed, nitrogen derived from the atmosphere, and grain yield. Genotypes showed significant variability in the amount of N-fixed, percent nitrogen derived from the atmosphere and grain yield. The mean symbiotic N contribution by the genotypes ranged from 53.6 kg/ha – 370.5 kg/ha. Grain yield was significantly different among the genotypes. Five genotypes showed superior performance for N-fixed and grain yield. There was high heritability, Phenotypic Coefficient of Variation and Genotypic Coefficient of Variation for the selected traits, which is required in breeding program for crop improvement. Genotypes should be re-evaluated in multi-locations to confirm performance and stability for release as varieties. Key words: Glycine max, genotypes, heritability, genotypic coefficient of variation, phenotypic coefficient of variation.
Characterization and conservation of germplasm is a critical step toward the genetic improvement of the crop. This study assessed variation in 257 common bean genotypes which included 207 accessions obtained the National Gene Bank of Kenya, 33 accessions from Kenya Agricultural and Livestock Research Organization (KALRO), 13 landraces collected from farmers’ fields and four commercial varieties for various agronomic traits. The experiments were laid out in a randomized complete block design with three replicates at Jomo Kenyatta University of Agriculture and Technology (Kenya) for four seasons between 2019 and 2020. Significant differences (P≤0.05) existed among the common bean accessions for all traits studied. Seed yield ranged from 220.6 to 4641.9 kg/ha (KNB0106) among the accessions with a mean of 1267.0 kg/ha. Significant (P ≤0.05) positive correlation was recorded for days to flowering and days to maturity (0.73), while 100-seed weight had a significantly negative correlation with the number of pods per plant (-0.66) and the number of seeds per pod (-0.65). High (>20%) broad-sense heritability was recorded for 100-seed weight (89.0%), days to flowering (76.8%), and grain yield (60.5%). Nineteen accessions that combined early maturity and high-yielding traits were identified. On average, higher seed yields were recorded for large-seeded and climbing genotypes compared to small-seeded and bush types. Common bean accessions characterized can be exploited in breeding programs. Key words: Common bean, agronomic traits, Phaseolus vulgaris, variability, broad sense heritability.
In the breeding of perennial plant species, the coefficient of repeatability is an important parameter because it allows for effective early selection of superior genotypes, thus saving time and cost. The objective of this study was to determine the minimum number of years required for observation to identify superior genotypes of coconut with a high degree of accuracy. Four hybrid varieties of coconut were evaluated in a randomized complete block design with two replications each year for four years (2009-2012) in Benin City, Edo State, Nigeria. The repeatability coefficient was calculated using principal components based on correlation and covariance matrices, and the minimum number of years required for observation to identify superior genotypes was estimated. The repeatability coefficient ranged from 0.63 to 0.90, while the coefficient of determination ranged from 0.87 to 0.97 for the two methods of principal component analysis for yield and its components. For each of the traits studied, the repeatability coefficient estimated by principal components based on correlation matrix was lower than the value obtained by the principal components based on the covariance matrix. Estimates of the number of years required for observation to identify superior genotypes based on correlation and covariance matrix of the principal component analysis ranged from 2-58 years at a pre-established reliability coefficient of 80-99%. Results from the simulation models showed that an increase in number of years of evaluation beyond four did not appreciably increase the precision for the selection of superior genotypes (R 2 > 85%) for each of the traits evaluated. Based on repeatability index, four-year yield records are adequate for the identification of superior genotypes with a high degree of accuracy.
Sorghum is one of the most important cereal crops in Ethiopia. However, the productivity of this important crop is low owing to different factors, of which Striga is most detrimental. Multi-environment performance evaluation was carried out consisting of 11 sorghum genotypes. The objective was to select better performing, Striga-resistant and stable sorghum lines. The trial was conducted at three Striga prone areas of North-east Ethiopia for two years. The result of combined analysis of variance across locations over the years showed that genotype × location × year of interaction significantly affected all traits except days to heading, which indicate the inconsistency of the genotypes in different locations and cropping seasons. All the genotypes supported significantly lower number of Striga than the susceptible and local checks. Log transformed value of Striga count ranged from 1.41 for G5 to 2.71 for G10. The performance of the genotypes on individual locations showed that G7 was the highest yielding genotype, followed by G9 on environment Kobo 03. The additive main effect and multiplicative interaction (AMMI) analysis of variance showed that the total G×E variance was explained by three significant interactions principal component axes (IPCAs), which contributed 95.8% in total, while the genotype and genotype by environment (GGE) explained 90.18% of the G×E variance. Based on Striga resistance, agronomic performance and yield stability of genotypes, G7, G8 and G9 were found to be better sorghum genotypes for the area under consideration. Genotype G9 is a brown seeded and short-stalked released variety; whereas G8 (Gambella1107 × P-9403), as it was preferred by farmers, has been released by the name Gedo for production in the Striga prone areas of North-eastern part of Ethiopia. The three genotypes could be used as sources of Striga-resistance in future crossing programs. Key words: Additive main-effect and multiplicative interaction (AMMI), desirable genotype, genotype and genotype by environment (GGE), interaction principal component axes (IPCAs), Striga hermonthica.
Twenty-one crosses developed from the frame of line × tester analysis along with ten parents were grown in two replicates experiment. Data on days to flowering, days to maturity, plant height, number of pods/plant, number of primary branches, number of secondary branches, number of tertiary branches, number of seeds per pod and seed yield per plant (g), revealed high significant differences exist among lines, testers and crosses for all traits studied. The ratio value of general combining ability variance to specific combining ability variance suggests the preponderance of non-additive type as well as additive gene action for some traits. Genotype Pusa-362 was the best general combiner for days to flowering. Genotype ICCL-87322 was identified as the best general combiner for the number of seeds per plant. Genotype BG329 was identified as the best general combiner for seed yield per plant (g) followed by KPG-59. Genotype PG-92-4 recorded desirable and significant GCA across five traits consistently. Cross PG-92-4 X Pant-186 recorded five significant SCA in the positive direction for secondary branches, number of tertiary branches, number of pods per plant, seed yield per plant and hundred seed weight. This cross is considered the most important compared to other materials under study. The proportional contribution of line × tester interaction was evident for most of the traits followed by the contribution of maternal lines. Days to flowering, days to maturity, primary branches, secondary branches, tertiary branches, pod per plant, seed per pod and seed yield per plant (g) recorded higher SCA variance suggesting non-additive gene action exit in expressing of these traits. The presence of a high SCA effect suggests that heterosis breeding can be exploited. Selection for those characters should be undertaken in later generations when these traits are fixed in homozygous lines. Key words: Chickpea, Cicer reticulatum, combining ability, gene action, heritability.
Dioscorea bulbifera L. is a widely distributed plant in the humid and sub-humid tropics.The taxonomic treatment of this species is ambiguous due to its extreme polymorphic morphological characters.Therefore, it is imperative to assess the species distribution, and the inter and intraspecific variability relationships in D. bulbifera.In this study, the genetic diversity and species distribution of 41 accessions of D. bulbifera in Uganda were investigated.Diversity among the 41 accessions was assessed using distribution of accessions, morphological descriptors and SNP markers.To investigate the relationship between individuals and populations, a heat map, phylogenetic tree, and principal components analysis were used.A total of 221455432 paired-end raw reads were generated out of which 162662 SNP loci were called with 150 bp reads (2×150) to a targeted depth of 112 million reads.Analysis of SNP data has proved a heterogenous population of D. bulbifera with an exception of Abur accessions that stand out as homogenous populations.This study has revealed that the utilization of advanced sequencing techniques such as GBS in combination with statistical analysis is a robust method for evaluating genetic diversity in a complex crop such as aerial yam.
