Indian Society of Genetics & Plant Breeding

Comparative study of radio-sensitivity and relative biological effectiveness of gamma rays, X-rays, electron beam and proton beam in short grain aromatic rice

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Knowledge about the type of mutagen used and its
optimized dose are of paramount importance to design
and implement any plant mutation breeding programme.
Present study was first time carried out to evaluate the
comparative effectiveness, radio-sensitivity behavior and
relative biological effectiveness of four physical mutagens
viz., gamma rays, X-rays, electron beam and proton beam
on two short grain aromatic rice landraces
viz., Samundchini
and Vishnubhog. The seeds of these two varieties were
treated with 15 different doses of all four mutagens, ranging
from 50Gy to 750Gy with an interval of 50Gy. Germination
percentage and seedling growth parameters were recorded
at seven and 15 days after sowing, respectively in two
replications. It was observed that germination percentage,
shoot and root length of the seedling gradually declined
with the increase in doses of all the physical mutagens. On
the basis of these observations, LD50 and GR50 doses
were calculated. The present study reports the optimum
range of doses for gamma ray (280 to 350 Gy); electron
beam (290 to 330Gy); X-ray (200 to 250 Gy) and proton
beam (150 to 200Gy). GR50 doses were observed higher
than LD50 doses for all the mutagens in both landraces.
However, Samundchini showed higher LD50 and GR50
doses than Vishnubhog indicating later to be more radiosensitive. Furthermore, both the genotypes were highly
radio-sensitive for proton beam and least for gamma rays.
Similarly, high relative biological effectiveness was observed
for proton beam followed by X-ray, electron beam and
gamma rays indicating their decreasing trend of penetration
capacity and lethality. Results of present study will be
useful for plant breeders to use the above mutagens in an
appropriate dose for mutation breeding in rice.

Keywords: Rice, landraces, physical mutagens, radiosensitivity, electron beam, proton beam, LD50, GR50


Year: 2020
Volume: 80
Issue: 4
Article DOI: 10.31742/IJGPB.80.4.3
Print ISSN: 0019-5200
Online ISSN: 0975-6906



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