Genetic analysis of some physiological traits in polycross populations of Dactylis glomerata under normal and drought conditions

Half-sib mating is an appropriate approach to estimate additive variance component of quantitative traits. This research was conducted to estimate genetic parameters of physiological traits and their response to drought stress in Dactylis glomerata. Twenty five half sib families derived from poly cross of 25 parental genotypes were evaluated under two moisture environments (normal and drought conditions) according to a randomized complete block design in the research farm of Isfahan University of Technology. Results indicated that drought stress significantly affected forage yield. Significant difference was observed among the families for all of the studied traits except for ratio of total chlorophyll to carotenoid and relative water content. Drought stress increased traits with respect to chlorophyll a/b and prolin in stress condition compared with normal condition while other traits decreased in drought condition. Genotypic coefficient of variation varied between 4. 5 to 31. 08 % under non-stress condition and from 5. 7 to 66. 27% in drought condition indicating high genetic variation in this germplasm. The highest narrow sense heritability was related to total chlorophyll (78%) and the lowest one was related to relative water content (29%) in non stress condition. Also، highest and lowest narrow sense heritability were related to proline content (66%) and relative water content (17%) respectively. Regarding high heritability of proline content and chlorophyll b under drought stress، indirect selection through these traits may facilitate breeding for drought tolerance.