Effect of Gamma Ray and Thermal Neutron Irradiation on Seed of Korean Lespedeza, Lespedeza stipulacea Maxim
The response of Korean lespedeza to gamma ray and thermal neutron treatment of dormant seed was studied through the R₄ generation. Seed samples from a single plant selection were treated with dosages ranging from 40 to 80 kr of gamma rays and 1 to 8 hours exposure to thermal neutrons. Dosages of 4, 6, and 8 hours exposure to thermal neutrons were lethal. Except for a 17% increase in plant survival for the 50-kr dosage of gamma rays, the 40-, and 2- hour dosages of thermal neutrons all reduced seedling emergence, seedling height, plant survival, and seed yield of the R/sub 1/ generation relative to the control. There was no apparent relationship between gamma ray dosage level and the amount of reduction for any of the characters studied, but with each increase in thermal neutron dosage up to the point of lethality there was a corresponding decrease in seedling emergence, seedling height, plant survival, and seed yield. All plants within 70.0% of the R/sub 2/ progenies were upright in growth habit (control- type), and all plants within 11.4% of the R/sub 2/ progenies were procumbent (mutant-type). Plants within the remaining 18.6% of the R/sub 2/ progenies segregated for growth habit, with 52.0% of the plants being scored as upright and 48.0% as procumbent. There was a spread in maturity of 45 days among the R2 plants. Mean dates of maturity were October 24 for the R/sub 2/ population, October 10 for the procumbent R/sub 2/ subpopulation, and October 27 for the upright R/sub 2/ subpopulation and the control population. The dates of maturity of the R/sub 3/ and R/sub 4/ lines were remarkably similar to those of the corresponding R/sub 2/ plants, relative to the control. A number of morphologically different mutant types in addition to the one for growth habit were observed. These included mutations involving plant size, leaf shape and color, flower structure and color, seed size, and sterility. Disease reaction scores for R/sub 4/ lines ranged from 1.5 to 7.0 for bacterial wilt and from 2.0 to 3.7 for tar spot based on a scale of 1 to 9. Comparative scores for the control for bacterial wilt and tar spot were 2.8 and 2.5, respectively. Percent leaves varied from a high of 65.6to a low of 51.9% among 23 R/sub 4/ lines in comparison with 54.0% for the control. Leaf percentages of 6 of the R/sub 4/ lines were significantly higher than that of the control, whereas none were significantly lower. None of the 23 R/sub 4/ lines tested were significantly higher in forage yield than the control, but 5 of this number were significantly lower than the control in this respect. Seed yields of 6 of the 23 R/sub 4/ lines were significantly higher than that of the control, and 9 were significantly lower. The range in genetic variability of all characters studied was increased above as well as below that of the control, indicating that worth- while advances can be made in the improvement of Korean lespedeza through the use of irradiation. (auth)
- Research Organization:
- Univ. of Arkansas, Fayetteville
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-16-031488
- OSTI ID:
- 4778355
- Journal Information:
- Crop Science, Vol. 2, Issue 4; Other Information: Orig. Receipt Date: 31-DEC-62; ISSN 0011-183X
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
Similar Records
INDUCTION OF MUTATIONS FOR RUST RESISTANCE IN WHEAT
Radiation Genetics in Wheat, VI