Agriculture Reference
In-Depth Information
Under exposure to radiation in the dose of 4000 R, the germination of seeds was
signifi cantly delayed. In metaphases after radiation of seeds, rearrangements of chro-
mosomal type prevailed. Rearrangements of chromatid type were also observed, but
their frequency did not differ signifi cantly from control (Table 24.2).
TABLE 24.2
Chromosomal and chromatid types of rearrangements in control experiment
Number of
plantlets
Number of
metaphases
Number of rear-
rangements (%)
Chromatid
rearrangements
(%)
Rearrangements of
chromosomal type
(%)
117
1316
2.96
2.58
0.38
Similar relationship between the number of rearrangements and the number of
metaphases with rearrangements under the radiation treatment of plantlets was ob-
served by Rapoport [13]. In this study, frequency of rearrangements also decreased in
the seeds with later terms of germination after a treatment with X-rays.
Phosphemid, on the contrary, caused only chromatid rearrangements in all variants
of the experiment. Under moderate concentrations of phosphemid, the frequency of
rearrangements in one cell did not exceed the frequency of metaphases with rearrange-
ments. Figure shows that phosphemid in a moderate dose (2 … 10 −3 M) causes rear-
rangements of chromosomes in the plantlets of fi rst plantlet—24 h after the soakage of
seed. Their frequency increases with the increase of term of fi xation.
FIGURE 24.1 Rearrangements of chromosomes in early plantlets after the treatment of seeds
by phosphemid in a concentration 2 × 10 −3 M
On a y -axis—rearrangements, %. X-axis represents the time after the soakage of
seeds: 24, 27, and 36 h. Plantlets were fi xed 3, 6, 9, or 12 h (numbers above columns)
after plantlet originates. Data are found to be statistically signifi cant.
 
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