Evaluation of Genetic Variation and Simultaneous Selection for Seed and Forage Yield in Selected Genotypes of Dactylis glomerata and Bromus inermis

Drought is one of the most important abiotic stresses limiting plant survival, growth, and production in many regions of the world. Approximately one-thirds of the world's agricultural lands are in arid and semi-arid regions, including Iran. Therefore, there is a need to improve plant cultivars with high adaptability and low water requirement. This study was conducted to evaluate the drought tolerance of Bromus inermis and Dactylis glomerata genotypes and investigate the relationship between seed yield and forage yield to select better genotypes in terms of these traits, simultaneously. In this study, 36 genotypes selected from polycross populations of both species were clonally propagated and evaluated under normal and drought-stressed conditions during 2014 and 2015 at the Research Farm of Isfahan University of Technology, Isfahan, Iran. In both species, high genetic variation was observed among genotypes for seed yield and its components indicating high potential for improving these traits through targeted selection in breeding programs. Drought stress negatively affected seed yield and its components and reduced the genetic diversity of most traits. Most of the studied traits had relatively high heritability; therefore, improvement of these traits is possible through recurrent selection in breeding programs. The significant association between seed and forage yield indicated that it is possible to select superior genotypes based on seed and forage yield in both normal and water stress conditions, simultaneously. However, the intensity of this association was higher in Dactylis glomerata than Bromus inermis. In both species and under both normal and drought stress conditions, better genotypes were identified in terms of seed and forage yield. These genotypes can be used in developing genetic populations for simultaneous improvement of seed and forage yield in future studies and also for the development of synthetic varieties in both species.