Effect of Drought Stress on Seed Germination Characteristics in the Populations of Four Native Species of Onobrychis sp. In Iran

In order to study drought stress tolerance in sainfoin (Onobychis sp.), two factorial experiments were conducted based on completely randomized design under laboratory and greenhouse conditions in Research Institute of Forests and Rangelands,  during 2014-2015. In this study, four species of O. michoxii, O. cristagalli, O. sativa, O. sabnitens were evaluated at four drought treatments (control 0, -0.3, -0.6, -0.9 MPa) in the laboratory and (FC100% field capacity, FC75%, FC50% and FC25%) in the greenhouse. Data collected and analysis for percentage and rate of germination root length, shoot length, seedling length, root/shoot length ratio (RS), seedling fresh and dry weight and seed vigor index. Results showed that in both experiments, by increasing drought stress,  germination percentage and rate, shoot length, seedling length, seedlings fresh and dry weight and vigor index decreased in all species and their lowest values were observed in laboratory (-0.9 MPa stress) and in greenhouse (25% FC). In terms of root length and RS, the trend was reversed. In fact, at stress intensity up to 0.6 MPa, the amount of these traits increased and then consistent or decreased.By comparison, among species in the laboratory, the highest mean values of germination percentage and seedling growth were belonged to O. sabnitens and O. michauxii. Under greenhouse conditions, O.michauxii was more efficient than other species and introduced as a drought resistant species for breeding improved varieties.