فیزیولوژی محیطی گیاهی (Mar 2009)
Effect of Vitrification on Survival of Medicago polymorpha L. Cryopreserved Seeds
Abstract
In this research a new method for long term conservation of Medicago polymorpha seeds was developed by using cryopreservation. Two year cold acclimated seeds, collected from Iran rangelands, were desiccated using silica gel for four days and then cryopreserved by vitrification method. Seeds were loaded by loading solution containing 2 M glycerol and 0.6 M sucrose for 20 min and then inserted into cryo-vials containing 0.5 ml PVS2 in 0 °C prior to direct immersed into liquid nitrogen. Seeds were kept in liquid nitrogen for a week then thawed in 37 °C water bath for 2 min. The seeds were rehydrated and detoxified in a solution of MS medium salts containing 1.2 M sucrose respectively for 5, 10 and 15 min in 22 °C. At the final stage of post-treatment, three different procedures were used: (a,b) placing seeds under running water for 30 min and 24 h before being transferred to petri-dishes containing moist filter paper, (c) sterilization of seeds with 2% hypochloride then placed on MS medium containing 0.5 mg/lit GA3. Germination percentage of cryopreserved seeds in all three post-treatments was higher than control (not cryopreserved seeds). This figure was respectively 94.37% and 98.21% for cryopreserved seeds of post-treatments a and b which was different at 0.05 levels with controls. However, germination percentage (76.16%) of cryopreserved seeds in post-treatment c showed no significant difference with control.
