Radiosensitivity and improvement of yield and disease resistance by induced mutations in mungbean (Vigna radiata (L.) Wilczek)

Major problems in mungbean production in the Republic of Korea are low seed yield, Cercospora leaf spot disease and shattering. Up to now there have been no appropriate gene sources available to solve these problems. Consequently, artificial induction of useful gene sources was the aim in this study. One local and an exotic variety were irradiated with X-rays and thermal neutrons. Mungbean seed was relatively resistant to X-rays and thermal neutrons as compared with soybean, and seedling height was shown to be a better indicative character in the study of radiosensitivity. The results indicate that a 40 kR, or a little higher, dose of X-ray irradiation and a 20x1012 n·cm-2·s-1, or a slightly lower dose of thermal neutron flux would be suitable for a practical mutation breeding programme. A promising mutant line was finally selected from a population of an X-ray irradiated local variety. The selected line has an increase in seed yield of 42% and was highly resistant to Cercospora leaf spot disease as compared with the mother variety. The increase in seed yield of the selected line could be attributed to an increase in the number of pods/plant and the number of pods affected by Cercospora leaf spot disease. (author). 6 refs, 1 fig., 9 tabs