Dagne, Kifle (PhD)Eshete, Million (PhD)Admas, Sintayehu2018-07-102023-11-082018-07-102023-11-082008-06http://etd.aau.edu.et/handle/123456789/7705Tef (Eragrostis tef (Zucc.) Trotter) is major cereal crop cultivated in Ethiopia. It occupies two million hectares of land each year. However, its productivity is constrained by drought. To curb the situation, assessment of drought-resistance related traits variability among recombinant inbred lines (RILs) is essential. Morpho-physiological drought related (pot) and meiotic behavior (laboratory) studies were conducted at Debre Zeit and Addis Ababa in 2007/08. For pot experiment, twenty-five RILs of a cross between Eragrostis tef and E. pilosa, their parental lines and standard check cultivar were laid dawn in RCB design with three replications under moisture stressed and non-stressed conditions to examine differences in some drought related traits. There was significant (p<0.05%) difference among lines for all characters considered except thousand seed weight and peduncle length under non-stressed and panicle seed weight under stressed conditions. Under non-stressed condition, GCV and PCV ranged from 1.4% to 58.96% and 1.8% to 52.6%, respectively while GCV range of 3.5% to 71.9% and PCV range of 3.8% to 72.3% was observed under stressed condition. More than 45% heritability was observed for all traits except number of tillers (21.8%) at stressed condition. Generally considerably high genetic advance as % of mean was obtained for most of the traits considered in the study except for days to maturity. Under non-stressed condition, strong positive correlation was revealed for grain yield with number of tillers, excised leaf water loss and water use efficiency, and strong negative correlation with total root length, root biomass and relative growth rate. Under stressed conditions, total root length, root biomass, water use efficiency and relative growth rate were positively correlated with grain yield, while drought susceptible index and excised leaf water loss showed strong negative correlation. Moisture stress prolonged the time to anthesis in few RILs and Key Murri, but accelerated for most other RILs, E. pilosa and standard check cultivar. Drought hastened root growth in most RILs, E. pilosa and the check but not for Key Murri and some RILs. RILs with lowest drought susceptibility index showed better yield under stress except RIL-183. Seventeen RILs were identified to be resistant and eight were drought susceptible. The laboratory study was conducted to examine meiotic behavior of F1-hybrid (E. tef x E. pilosa) and pollen fertility of the F1-hybrid, parental lines and RILs. The F1-hybrid showed regular meiotic cell division and high level of pollen fertility (94.3%). Pollen fertility test of the parental lines and selected RILs was also high (90 to 95%). The result demonstrated the presence of wide variability among RILs for drought related trait and the potential of E. pilosa to diversify tef germplasm for drought related traits. Therefore, drought resistant RILs were identified which can serve as breeding materials for further research work. Key wards: Drought resistance, meiotic behavior, RILsenDrought resistancemeiotic behaviorRILsThesis