Breeding potential of durum wheat landraces from Jordan

The influence of drought stress on grain yield and developmental phases was studied in 132 landrace genotypes (LR) of durum wheat from Jordan. A number of old (OV) and improved (IV) durum wheat varieties, and F 6 selections from crosses (CR) between LR and IV were included. A total of 320 genotypes were planted in an observation nursery, with two replicates, in a semiarid (El) and an arid (E2) environment. Stress susceptibility (SI) and growth inhibition (GI) indices were calculated for each entry, based on grain yield and plant height, respectively. Potential yield (Y d ), in El and yield under stress (Y d ) in E2 were significantly correlated (r = 0.227; P = 0.02); however, the genotype x environment interaction was significant. IV genotypes had the highest Y d in El (3562.9 kg ha ‐1 ), but not in E2 (Y d =893.6 kg ha ‐1 ). LR genotypes had a lower Y d than IV genotypes in El (2736.5 kg ha ‐1 ) and a higher Y d in E2 (923.3 kgha ‐1 ). The highest variability for grain yield in both El and E2 was displayed by CR genotypes. SI was positively correlated with Y d in El (r = 0.745; P = 0.000) and negatively with Y d in E2 (r =–0.328; P = 0.001). Also, SI was significantly correlated with days to heading and filling period in both El and E2, and with days to maturity in El. CR genotypes differed in their SI estimate (0.915) from IV (1.068) and OV (1.026). Percent growth inhibition (GI) due to stress was highest for OV (48.8) and IV (46.3); it was intermediate (37.9) for CR and lowest (33.6) for LR genotypes. A number of LR and CR genotypes have been identified with high yield potential in El and above average yield in E2. A selection index was developed and is based on SI, GI, days to heading, and filling period.