Genetic variation is a source of phenotypic diversity and is a major driver of evolutionary diversification. Heritable variation was observed and used thousands of years ago in the domestication of plants and animals. The mechanisms that govern the inheritance of traits were later described by Mendel. Plant breeding requires genetic variation of useful traits for crop improvement. The induction of mutations has been used to enhance the yield, better nutritional quality and wider adaptability of world's most important crops such as wheat, rice, pulses, millets and oilseeds. The total area covered by commercially released mutant cultivars clearly indicates that they have played a significant role in solving food and nutritional security problems in many countries. Of all the mutant varieties developed, majority of mutants were produced through direct mutagenesis of the plant propagules and also there are several reports of mutants derived by irradiating rooted stem cuttings, which paves the way for in vitro mutagenesis. The incorporation of desired traits from non-adapted landraces or crop wild resources can speed up crop improvement. Among the different strategies to enhance crop improvement programs, induced mutagenesis has contributed immensely by creating mutant varieties with improved and desirable genetic changes in agronomic ally important traits of the crop plants. Such genetic changes can occur spontaneously naturally at a very low rate or experimentally induced by physical and chemical mutagens. Conventional mutation techniques have often been used to improve yield, quality, and disease and pest resistance in crops or to increase the attractiveness of flowers and ornamental plants. In general, mutation is the main source of genetic variation, which is the raw material for evolution by natural selection. Recognize that mutations are the basis of microevolution and that adaptations enhance the survival and reproduction of individuals in a population. Mutation breeding has greater impact in sustainable crop production by developing new mutant varieties. With the advances in genomics research and availability of genome sequences, induced mutants continue to be a genetic resource for elucidating genetic mechanisms and metabolic pathways. Agricultural sustainability and food security are major challenges facing continued population growth. Integration of existing and new technologies for the induction and exploitation of genetic diversity towards developing healthier, nutritious and productive crops is the need of the hour. Mutagenesis is a proven technology for the development of improved or novel varieties with desirable traits. Several mutant genes have been successfully explored, either directly or indirectly, to complement crop productivity.

The success of a plant breeding program greatly depends on the right choice of parents for hybridization and the gene action of different economic traits. Genetic variation is a key component in broadening gene pools in any given crop population and is critical to the success of yield improvement program. However, limited genetic variation and lack of potential parents and hybrids are the most limiting factors for improvement of sorghum in the moisture stress areas. Therefore, the study was conducted to estimate the combining abilities and determine gene action governing the quantitative traits for yield and its components using line x tester mating design. The experimental materials consisted of fifteen parents along with their twenty six hybrids and one standard check. The experiment was laid out using alpha lattice design with two replications at Mieso and Kobo during the main cropping season of 2019. For all of the traits studied, the combined analysis of variance indicated highly significant variations due to genotypes, indicating the presence of considerable genetic variation among genotypes. Inbred lines 3 and 4 were selected as the best general combiners for both days to flowering and plant height traits, while inbred lines 2 and 7 were identified as the best general combiners for stay green traits, based on general combining ability analysis. Thousand seed weight showed best general combiners in inbred line 6, 10 and 12. The hybrid crosses 4x14, 8x15 and 11x14 were identified as best specific combiners for grain yield while hybrid 1x15 was best specific combiner for days to flowering, days to maturity, panicle length, panicle width and thousand seed weight. The estimates of general and specific combining ability revealed the preponderance of non-additive gene action since the ratio of general combining ability to specific combining ability was less than unity for all the traits under study except for plant height. Eventually, Inbred lines 4, 9, 10, 11, 12, 13 and hybrid crosses 4x14, 8x15, 1x15, 11x14, 11x15, 13x14, 6x15 were found to be the most promising and potential genotypes that could be exploited commercially after critical evaluation for superiority and yield stability across locations over years, based on combining ability estimates and nature of gene action for grain yield and its components.

The most important prerequisite in crop improvement is the selection of suitable parents, which could combine well and produce desirable hybrids. However, narrow genetic base, lack of potential hybrids and lack of information on the genetic components are the most important limiting factors for sorghum yield improvement. Therefore, the present study was conducted to estimate the combining abilities and heterosis for yield and its components. A total of 42 sorghum genotypes were evaluated using alpha lattice experimental design with two replications at Mieso and Kobo during the cropping season of 2019. Combined analysis of variance revealed highly significant differences due to genotypes for all studied traits over locations, which indicates the availability of substation genetic variation among genotypes. Based on general combining ability analysis, inbred line 3 and 4 were identified as best general combiners for both days to flowering and plant height traits whereas inbred line 2 and 7 were identified as best general combiners for stay green traits. The hybrid crosses 4x14, 8x15 and 11x14 were identified as best specific combiners for grain yield while hybrid 1x15 was best specific combiner for days to flowering, days to maturity, panicle length, panicle width and thousand seed weight. The estimates of general and specific combining ability revealed the preponderance of non-additive gene action since the ratio of general combining ability to specific combining ability was less than unity for all the traits under study except for plant height. The maximum grain yield was obtained from a hybrid 4x14 (6.32 tha-1) followed by hybrid 8x15(5.92 tha-1), 1x15 (5.88 tha-1), 13x14 (5.78 tha-1) and 6x15 (5.57 tha-1) with the average value of 5.0 tha-1 which had higher mean value than the mean of the parents and the check. Among the hybrids, 8x15 recorded maximum heterosis (112.41%) over the mid parents, hybrid 1x15 revealed maximum heterosis (68.71%) over the better parent whereas 4x14 recorded maximum grain yield with (30.71%) heterosis over the standard check for grain yield. Finally, based on mean yield performance, heterosis response and combining ability estimates for grain yield and its components, the hybrid crosses 4x14, 8x15, 1x15, 11x14, 11x15, 13x14 and 6x15 were found to be the most promising and potential hybrids which could be exploited commercially after critical evaluation for their superiority and yield stability across the locations over years.

The ultimate purpose of a crop improvement program is to develop high yielding cultivars with desirable traits for farmers. However farmers in marginal areas still grow low-yielding, disease- and pest-prone sorghum land-races. In order to address the issues of farmers' selection criteria, an experiment was conducted at Hirna and Chiro with the objectives of evaluating adaptability and identifying farmers' preferred traits. During the 2019 main cropping season, a total of six sorghum varieties were evaluated using a randomized complete block design. Direct-matrix and pair-wise ranking algorithms were used to evaluate farmers at the flowering and maturity developmental stages. Grain yield, biomass, seed color, disease resistance, and seed size characteristics were given priority by farmers when evaluating and selecting their preferred varieties. At a 1% probability level, the combined analysis of variance results revealed the existence of highly significant genetic variation among varieties for all the traits under study. The maximum grain yield was obtained from Dibaba (11.375tha-1) and Jiru (10.175tha-1) varieties, which were also, identified as the superior improved sorghum varieties by field experiment and farmer visual observation. The correlation between grain yield and days to 50% flowering (0.91**), days to maturity (0.73**), and thousand seed weight (0.91**) was positive and highly significant. Based on the preferences of farmers as a whole, Dibaba and Jiru were ranked first and second and followed by Adelle, Chiro, and ETS2752 respectively. As a result, farmers' evaluations and the result of field experiments led to the choice of the varieties Dibaba and Jiru due to their superior performance compared to the other varieties. Dibaba and Jiru improved sorghum varieties were thus recommended for multiplication and distribution to farmers through both formal and informal seed systems as the experiment's result. In general, plant breeders and farmers' perspectives were combined to boost acceptance rates and make effective breeding programs for future improvement.

Common bean is playing a crucial role across the world mainly in the warm and lowland areas of the country including Ethiopia. Understanding the level of drought tolerance of the varieties available in each country is of paramount importance for breeding common bean for drought adaptation. However, the production of common bean is mainly limited due to lack of high yielding potential varieties and frequent and recurrent drought. Hence, the study was aimed to evaluate and identify the superior performance and genetic potential of improved common bean varieties for yield and yield related traits against drought. A total of 10 recently released improved common bean varieties were evaluated using a randomized complete block design (RCBD) with three replications at Mieso during the main cropping season of 2018 and 2019. The information generated on the drought tolerance of the available varieties should help in the design of a breeding strategy that incorporates adaptation traits with commercial characteristics preferred by common bean farmers for varieties to be grown in diverse environments. The combined analyses of variance revealed the presence of tremendous genetic variation among improved common bean varieties for all the studied traits except plant height and stand count at harvest, which implies the availability of substantial genetic variation among varieties. Overall, SER-125, SER-19 and Nasir common bean varieties had better performance compared to the other varieties for yield and the yield related traits. The maximum grain yield was obtained from SER-125 (2620 kgha -1 ) followed SER-19 (2612 kgha -1 ) and Nasir (2583.33 kgha -1 ) common bean varieties and identified as the superior improved common bean varieties. Eventually, the effect of varieties on grain yield was significant and the best performing varieties of common bean would be recommended for the specific community and its vicinity even though further study should be carried out including a number of recently released varieties for improved common bean production in the target area and also to put the recommendation on strong basis. Therefore, based on the results of this adaptation experiment, SER-125, SER-19 and Nasir were recommended for production and adoption at Mieso and other similar environments.