The demand and use of improved crop varieties by farmers has increased in the central highlands of Ethiopia, where continuous loss of local traditional varieties has been occurring in the last two to three decades. The objectives of the study were to assess the extent of genetic erosion and perception of farmers and associated causes for the reduction of traditional farmers' varieties. Direct field assessment covering 56 wheat farms and a survey in which 149 farmers participated were carried out in three districts of central Ethiopia. Based on data collected during direct farm assessment, the loss of genotypes was found to be 88% in Ada followed by 80% and 60% in Lume and Gimbichu districts, respectively. The farmer survey indicated an even greater loss of diversity of100% in Ada followed by Lume (93%) and Gimbichu (67%). Diseases and pests as well as shorter growing seasons associated with climate change were identified as main causes for farmers to switch to modern varieties. The expansion of high yielding improved bread and durum wheat varieties also contributed to gradually replace local durum wheat varieties by local farmers of these districts. Overall, genetic erosion of tetraploid wheat varied among the three districts of central Ethiopia. Reductions in the number of farmers and area coverage in the study districts could be used as good indicators for the existence of genetic erosion.

No abstract

Development of low-nitrogen (N) tolerant and N-responsive durum wheat genotypes is required since nitrogen efficiency has emerged as a highly desirable trait from economic and environmental perspectives. Two hundred durum wheat genotypes were evaluated at three locations under optimum (ON) and low (LN) nitrogen conditions to screen genotypes for low-nitrogen tolerance and responsiveness to an optimum N supply. The results showed significant variations among the durum wheat genotypes for low-N tolerance and responsiveness. The average reduction in grain yield under the LN condition was 48.03% across genotypes. Only 17% of the genotypes tested performed well (grain yield reduction <40%) under LN conditions. Based on the absolute grain yield, biomass yield, and normalized difference vegetative index value, on average, 32, 14, 17, and 37% of the tested genotypes were classified as efficient and responsive, efficient and nonresponsive, inefficient and responsive, and inefficient and nonresponsive, respectively. Considering the absolute and relative grain yield, biomass yield, normalized difference vegetative index values, and stress tolerance indices as selection criteria, 17 genotypes were chosen for subsequent breeding. Among the screening indices, geometric mean productivity, stress tolerance index, yield index, and stress susceptibility index exhibited positive and significant correlations with grain yield under both N conditions; hence, either of these traits can be used to select low-N-tolerant genotypes. The common genotypes identified as LN-tolerant and responsive to N application in this study could be used as parental donors for developing N-efficient and responsive durum wheat varieties.

This study was conducted to investigate the variability of Ethiopian black cumin genotypes by using morpho-agronomic traits. Sixty-four genotypes were tested at Debre Zeit and Kulumsa Agricultural Research center in 2021 using an 8 × 8 simple lattice design with two replications. Analysis of variance revealed significant (p ≤ 0.001 or p ≤ 0.01) differences among the genotypes for all traits studied except the number of primary branches per plant. The effect of location was significant (p ≤ 0.001 or p ≤ 0.05) for all traits except the number of primary branches per plant. It is expected to improve all phenological traits as well as seed yield and yield-related qualitative traits by 4 to 41% over improved varieties by the selection of the top 5% landraces. Thus, through selection, it would also be possible to shorten the flowering and maturity periods of the genotypes. High broad sense heritability values coupled with high to moderate genetic advance as a percentage of mean values were shown by the number of capsules per plant, seed yield per plot, and plant height which indicates possibilities for improvement of these traits through selection. Plant height and seed yield per plot had moderate to strong positive and significant (p ≤ 0.01) phenotypic and genotypic association (r = 0.53 to 0.99) with seed yield per hectare. Plant height, number of primary branches per plant, and seed yield per plot had a positive direct effect on seed yield per hectare phenotypically and genotypically. This would be a direct selection criterion for further improvement of the genotypes. The principal component analysis of 13 quantitative traits exhibited 81.7% of the total variance captured by the first four principal components (PCs). Days to flowering, days to 50% flowering, days to full blooming, days to maturity, number of seeds per plant, and seed yield per plant were the main contributor traits for the variation in the first and second PCs. The genotypes were grouped into three different clusters (C-I = 39.06%, C-II = 9.38%, and C-III = 51.56%) based on 13 quantitative traits with significant intra- and inter-cluster distances. This clearly showed that there was sufficient diversity among the genotypes which can be exploited for the future black cumin improvement program.