THE USE OF X-RAY AND THERMAL NEUTRONS IN PRODUCING HERITABLE CHANGES OF RICE
Five varieties of Ponlai rice seeds were irradiated in 1957 at the Brookhaven National Laboratory. Seed samples of 200 grams of each variety were exposed to x rays, one batch at 20 Kr and one at 25 Kr, and thermal neutrons, one batch for 15 hrs and another for 20 hrs (flux x time was 3.60 x 10/sup 13/ and 4.90 x 10/sup 13). The seeds were grown and the plants and their yields were compared with control plots of untreated seeds. Inhibition of seedling growth was more pronounced in seeds exposed to thermal neutrons. Heading dates, in general were delayed. In the R/sub 2/ generation 0.09 per cent of the plants showed early maturity mutation. In the R/sub2/ generation albino plants (deficiency of chlorophyll) were observed. None survived for transplanting. Other mutations as awned, full color, narrow or broad leaf, grown habit, and pleotropic change of morphological character were also observed. The rate of mutation varied with the type and amount of radiation. Sterility was pronounced in the R/sub 2/ generation, more than 8% showed partial sterility and 0.5% were totally sterile. Cytological studies both in R/sub 1/ and R/subv 2/ generations using acetocarrnine smear preparations indicated that the frequency of aberration was closely associated with sterility in R/sub 1/ generation. Most chromosome aberrations were tetravalents formed in chain, ring, or other shapes. A few chromosomal bridges were also found in R/sub 1/ generation. The frequency of aberration increased with rate of treatment and also varied with the varieties. All early maturing and other beneficial mutations in R/sub 2/ generation were selected and grown as plant progeny rows in R/sub 3/ generation. Most of them bred true and were harvested for yield and disease resistance tests in the R/sub 4/ generation. (TTT)
- Research Organization:
- Taiwan Provincial Coll. of Agriculture, Japan
- NSA Number:
- NSA-16-020180
- OSTI ID:
- 4839470
- Journal Information:
- Ho Tsu K'o Hsueh, Vol. Vol: 3: No. 1; Other Information: Orig. Receipt Date: 31-DEC-62
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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