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Knowledge of the genetic control of characters is essential for breeders to decide on the breeding procedure to follow. The aim of this study was to determine the nature of gene action in the inheritance of major quantitative traits in sesame. Ten parents of sesame were crossed in year 2011 in a 10 x 10 full diallel mating system. Data were collected for major agronomic traits, grain yield and oil content. F1 progenies along with their parents were evaluated during 2012 cropping season in a randomized complete block design with three replicates at Uke and Wama trial sites of Bako Agricultural Research Center. For all traits, general (GCA) and specific (SCA) combining abilities were highly significant. Mean square for reciprocal effects were significant for all traits except plant height. Inbred lines Dicho, EW002, BG006, Obsa and EW003-1 had positive GCA effects for seed yield per plant. Parental line BG006 had high GCA for oil content. For seed yield per plant, direct crosses BG006 x EW003-1, EW023-2 x Wama, EW003-1 x EW019 and EW003-1 x EW010-1 had high SCA effects, while EW019 x Dicho and Obsa x Dicho had high SCA for oil content. For seed yield per plant, reciprocal crosses EW010-1 x EW002, EW006 x BG006, EW003-1 x EW023-2 and Dicho x EW006 were good combiners. Reciprocal cross Wama x EW019 was the best for its high SCA for oil content. The predominance of non-additive gene actions in all traits considered in this study suggested the exploitation of hybrid vigor as the best approach in sesame breeding. The result of this experiment indicated that maternal effects were important in sesame breeding for high seed yield.&nbsp

The nature of gene action governing the expression of various traits is very helpful in formulating an effective and sound breeding program. The objective of the present study was to determine the type and magnitude of gene action in sesame using generation means analysis to provide a basis for an evaluation of selection methods for the improvement of sesame. The six basic generations parent 1(P1), parent 2 (P2), hybrid (F1), F2, back cross 1(BC1) and back cross (BC2) of five crosses such as cross-1 (EW002 x BG006), cross-2 (Dicho x EW006), cross-3 (EW002 x Dicho), cross-4 (Obsa x Dicho) and cross-5 (EW002 x Obsa) were planted in 2012 and 2013 at Uke trial site of Bako Agricultural Research Center in a randomized complete block design, with three replications. The combined analysis of variance indicated highly significant differences among generations for all the traits in all crosses. Simple additive-dominance model exhibited lack of good fit for all the characters studied in all the crosses, except days to maturity in cross 2. The result of the generation means analysis showed that days to flowering, plant height, branches per plant, and capsules per plant and yield per plant were found to be under the control of additive and non-additive gene effects, coupled with duplicate type of epitasis. Biparental mating followed by selection of desired recombinants from the segregating population is the most applicable breeding methodology for traits under the influence of duplicate type of epitasis. Complementary type of epitasis was only observed for plant height in cross 1 and capsules per plant in cross 3, which appeared to be desirable and would be helpful in further improvement of these traits.

Heterosis breeding is a technique with potential to improve sesame yield. The productivity of sesame need to be increased significantly to exploit the maximum benefit from the increasing world market demand for this crop as well as to reduce the deficit in edible oil in Ethiopia. The objective of this study was to determine the extent of heterosis for yield and yield related traits in sesame. The present investigation on sesame comprised a full-diallel set of 10 parents and their 90 F1 crosses. The hybrids were produced during the main growing season of 2011. Seeds of all F1 and their parents were planted in randomized complete block design, with three replications at two experimental sites viz., Uke (1383 meters above sea level) and Wama (1436 meters above sea level) of Bako Agricultural Research Center on 12 and 14 June 2012, respectively. The data was recorded for four traits viz., days to flowering, branches per plant, yield per plan (g) and oil content (%). Analysis of variance computed for each location and over locations revealed highly significant differences among the parental lines and F1 hybrids for all the studied traits. The magnitude of mid and better parent heterosis for seed yield ranged from -40.0 to 31.6-% and-40.2 to 23.3%, respectively. The range of standard heterosis for yield and oil content was -41.8 to 13.6% and –5.6 to 7.8%, respectively. Seven crosses of F1 and reciprocal F1 displayed positive and significant standard heterosis for number of branches per plant while a total of 35 (37.6%) crosses of F1and reciprocal F1 had negative better parent heterosis for days to flowering of which 18 (20.0%) displayed negative and significant standard heterosis. A total of 16 crosses (of F1 and reciprocal F1) displayed positive better parent heterosis for seed yield per plant, of which BG006 x EW003-1, EW023-2 x Dicho and BG006 x EW002 crosses of F1and rcecprocal F1 exhibited positive and significant standard heterosis of 10.5, 29.4 and 13.6%, respectively. All except two crosses of F1 displayed positive standard heterosis for seeds oil content of which 74 (82.22%) of crosses exhibited positive and significant standard heterosis. The different magnitude of heterosis displayed by some crosses of F1 and their reciprocal F1 for all characters indicated the presence of maternal inheritance, which suggested the importance of considering the use of female parents in the respective crosses and characters to maximize the exploitable heterosis in hybrids. Generally, the results of the research revealed higher chances of producing heterotic sesame hybrids that combined the highest yield, oil content, early maturity and high number of fertile branches. This suggests that heterosis breeding and/or hybridization could be one of the breeding methods in sesame in Ethiopia to produce heterotic hybrids that combine desirable traits as many as possible or to develop potential recombinant pure lines from segregating generations., East African Journal of Sciences, Vol. 13 No. 1 (2019): East African Journal of Sciences

Journal of Science and Sustainable Development, Vol. 5 No. 2 (2017)

Linseed (Linum usitatissimum L.) is important to the Ethiopian farmers in terms of its various home uses generating potential in both domestic and foreign markets. One of the major linseed production constraints in the country is the lack of high yielding and high oil content varieties. This experiment was conducted at Hossaina, Kokate, Dida-Midore and Holeta to assess the genotype-by-environment interaction (GEI) among the varieties for yield and oil content. The experiment was carried out using nine released out and three pipeline varieties with a local cultivar. The analysis of variance of AMMI exhibited a very highly significant (P ≤ 0.001) variation due to varieties and locations for grain yield, oil content and oil yield, but GEI was significant for oil content and oil yield and not for grain yield indicating that the stability of the genotypes over the range of locations tested. The genotypes CI-1652, Tolle, Kassa-2, CI-1525, Jeldu, and Kulumsa-1 for oil content and the genotypes Kassa-2, Jeldu and CI-1525 for oil yield formed the first adaptive group with high mean and IPCA1 closer to zero IPCA1 indicating that they were the most stable and had wider adaptability across the studied environments. The AMMI selections for oil content and yield per environment included Kassa-2 in all the four locations; Jeldu in Holeta and Kokate; Kulumsa-1 in Dida-Midore, Hossaina and Kokate; CI-1525 in Holeta and Hossaina; Dibannee in Hossaina for both oil content and oil yield but in Kokate only for oil yield.

Information on phenotypic stability is useful for the selection of crop varieties as well as for designing appropriate breeding strategies. The present study was designed to determine the stability of sesame genotypes for seed yield and to elucidate interrelationships among the stability parameters and their associations with mean seed yield. Ten sesame genotypes were tested in four locations in 2011 and 2012 crop seasons using a randomized block design, with three replications. Nine statistical methods were used to determine seed yield stability of the sesame genotypes. The results of the various statistical analyses showed significant variations in seed yield due to genotype, location, and genotype x location interaction. Mean and cultivar superiority performance (Pi) showed high correlation with yield. Cultivar superiority measure (Pi) was significantly associated with S1 and S2. The positive correlation between Wricke and Shukla was perfect and the two procedures are equivalent for ranking purposes. Hence, either Wricke or Shukla can be used. Nassar & Hühn’s absolute rank difference (S1) and variance of ranks (S2) were correlated positively and highly significantly (r = 0.99**), hence either of them can be used. The correlations among the stability parameters S2di, Wi, 2i, ASV, S1 and S2 were positive and significant. Two genotypes, viz., EW002 and BG006, have been  identified as stable with high mean seed yield and could be recommended for western Ethiopia. It could be concluded that both seed yield and stability should be considered simultaneously to exploit the useful effect of G x E interaction and using non-parametric stability measurements as an alternative to parametric stability measurements is important.  Keywords: Genotype; G x E Interaction; Sesame; Stability; Yield Â, East African Journal of Sciences, Vol. 8 No. 2 (2014): East African Journal of Sciences Volume (8) N0 2

As sesame is a short day plant and sensitive to light, heat, and moisture stress the yield is not stable. The selection of stable genotypes that interact less with the varying environment in which they are to be grown is required. The extent of genotype by environment interaction indicates the likelihood of adaptation of a given genotype to a particular agro-ecology and helps to design a breeding strategy for developing varieties suitable for cultivation in a target area. The objective of the study was to assess the significance and magnitude of GEI effect on sesame seed yield and to evaluate the efficiency of the combined use of AMMI and GGE techniques to study GEI. The treatment consisted of ten sesame genotypes grown in four locations (Angar, Uke, Wama and Bako) in western Ethiopia during the 2011 and 2012 main cropping seasons (June to October). The experiment was laid out as a randomized complete block design with three replications. The seed yield data were analysed using additive main effects and multiplicative interaction (AMMI) and the genotype and genotype x environment interaction effect (GGE) biplot. The AMMI analysis showed that environment, genotype, and genotype by environment interaction significantly (P, East African Journal of Sciences, Vol. 9 No. 2 (2015): East African Journal of Sciences Vol (9) No 2

The progress made to improve groundnut varieties through breeding in Ethiopia has not been yet assessed. Therefore, in this study genetic gain in grain yield and yield related traits of 14 groundnut varieties developed by the Ethiopian Lowland Oil Crops Research Program (now Ethiopian Lowland Oil Crops Research Project) from 1976 to 2009 was assessed. The varieties were evaluated in RCBD design with three replications in the 2010 main cropping season at Melka Werer Agricultural Research Center and Miesso experimental fields. The analysis of variance indicated significant differences among the varieties for all traits except days from sowing to emergence. Positive genetic gains were observed for the yield traits (grain yield and yield components), while negative genetic gains were obtained for the phenological traits (50% flowering and pod filling periods). Grain yield was increased from 1.52 to 2.74 tons ha-1 during the last 33 years and the overall increase in seed yield of the latest variety Fetene over the oldest variety Shulamith was estimated to be 1.142 tons ha-1 or 71.4%. Based on the regression analysis, the estimated average annual rate of increase in grain yield potential was 0.03 tons ha-1 year -1 with an annual relative genetic gain of 1.89%. These results demonstrated the efficiency of the adopted breeding strategies in developing varieties with higher grain yields and earlier maturity. This suggests that groundnut breeders can use similar breeding strategies to exploit the genetic potential of the crop for enhanced production., East African Journal of Sciences, Vol. 6 No. 2 (2012): East African Journal of Sciences