Effect of osmopriming on the enhancement of seed germination and seedling growth of deteriorate seeds of sainfoin (Onobrichis viciifolia) in basic and active collections of gene bank

    In order to study the effects of storage conditions and osmopriming on the seed germination and seedling growth of sainfoin (Onobrichis vicifolia), two factorial experiments were conducted based in a completely randomized design with three replications in the laboratory and greenhouse of Research Institute of Forests and Rangelands, Tehran, Iran in 2015. The first factor was accessions origin (Khonsaer, Karaj, Ardebil, and Tehran), the second factor was seed storage conditions at two levels: basic storage (-18ºC) and active storage (+4ºC), and the third factor was seed priming at six levels, including soaking in different concentration of PEG 6000 solution for 24 hours to produce 0, -3, -6, -9 and 12 Bar osmotic potential and control (no priming). The seeds samples of 15 to 20 years ago that were kept in gene bank storages were examined. In the laboratory experiment, seeds were sown in Petri dishes, irrigated and placed in germinator in standard conditions (20°C) for two weeks. Germinated seeds were counted every two days and after two weeks seed germination was recorded. In the greenhouse experiment, 25 seeds were sown in each one-liter pot filled by an equal amount of soil, sand, and compost. Data were collected for germination traits as germination rate, radicle length, shoot seedling length, vigor index, root/shoot length ratio (RS), and seedling fresh weight. The results showed that the seeds in basic storage (-18ºC) had higher germination percentage, germination rate, and vigor index as compared with active storage. The effects of different priming levels showed that seed germination and germination rate were increased by application of hydropriming (distilled water), whereas, for radicle length, shoot seedling length, vigor index and seedling fresh weight and RS, the higher values were obtained by osmopriming in both laboratory and greenhouse condition.