BIOLOGICAL EFFECTS AND RAPD ANALYSIS OF ALFALFA (medicago sativa L.) IRRADIATED BY FAST NEUTRONS

Dry seeds of alfalfa variety Zhaodong were irradiated by fast neutrons generated by linear accelerator with three fluences,3.60×1011,7.10×1011 and 3.54×1012/cm2 respectively.Seed germination,growth,and RAPD analysis on the mutation were reported in this study.The results showed that germination vigor and germination rate of irradiated seeds were higher than those of control,but seedling height and root length were reduced with the increase of fluences.When the dosages reached 3.54×1012/cm2,seedling root length decreased by 81.63% compared with the control,but the seedlings didn't grow any true leaves except for cotyledon.36 primers were used in RAPD analysis,and the results showed that the RAPD polymorphic loci rate was 7.25%,6.52% and 5.80% among the 3.60×1011/cm2,7.10×1011/cm2 and 3.54×1012/cm2 treated M1 plants.RAPD polymorphic loci rate in the 3.60×1011/cm2 treated plants was the highest among three treatment.It is concluded that 3.60×1011/cm2 could be on optimum fluences for alfafa mutation by fast neutrons.