Research In The Tissue Culture And Mutation On Breeding Of Sweetpotato

Sweet potato,an important food and economical crops,is widely cultivated in our country. In the recent years, increasing soil salinization limit the planting scale and yields of sweet potato , so it has practical meaning to carry out studies about salt tolerance.The salt tolerant mutant selection in vitro was systematically studied by 60Coγ-ray radiation,EMS treatment and composite method by using the sweet potato stems as the material, NaCl as the selection pressure,and got better results.Different temperature ,illumination ,sugar and hormone in tissue culture of sweet potato were studied with stem segment . The results showed that high temperature and strong light were beneficial to promote rooting and sturdy stem;Sugar and sucrose were helpful to the growth of sweet potato than glucose,so we can use sugar instead of sucrose in order to save cost. IAA could promote the growth of sweet potato stem;Lower concentration of IAA showed a promoting effect while higher concentration inhibited plant growth.Study of radiation mutation showed that the number of leaves and roots were inhibited with the increase of irradiation dose in different degree ,and more the radiationg dose was given ,the more serious inhibition was.The dose of 30 Gy was recommended as suitable irradiation dose for stem segments . The lethal dose was 50 Gy.Study of EMS mutation showed that the concentraions and treatment time of EMS was closely related with the injury on stem segments. Increase in the radiation dose aggravated the physiological injury .Taking both the surival and the mutational effect into account,we suggested the the best method for EMS treatment was treating the stem segments with 0.3 %+1 h or 0.2 %+(2-3) h. The lethal dose was 0.4 % +3h.The results of compound mutation showed : Compound mutation has interaction effect on injury of stems.We suggested the optimal treatment is 30 Gy and 0.2 %EMS treament for 2-3h.The outside indexes analysis and physiological and biochemical indexes showed the induced mutants could resist salt stress by decreasing content of the MDA and Chlorophyll ,and increasing content of the free proline.Salt tolerance tests in vitro revealed that the mutants possessed salt tolerance and had genetic stability.