Agriculture Reference
In-Depth Information
TABLE 24.1
Rearrangements of chromosomes in the early plantlets of
Crepis capillaris
after
radiation treatment of seeds by X-rays
Time
(h)
Number of meta-
phases
Number of rearrange-
ments
∑
With rear-
range-men-
ts
∑
+m (%)
∑ (%)
3000
22
0*
5
50
39
78.0
50
100.0
22.0
24
3
16
334
179
53.6
203
60.8
7.2
6
13
177
64
36.2
68
38.4
2.2
27
2
21
184
96
52.2
123
66.8
14.6
6
11
273
104
38.1
124
45.4
7.3
9
9
377
101
26.8
106
28.1
1.3
38
0*
8
96
35
36.4
38
39.6
3.2
2000
24
4
19
134
53
39.7
61
45.5
5.8
29
3
22
229
58
25.3
61
26.7
1.4
4000
Growth is delayed by 30-39 h
Control
18
1316
39
2.96
39
2.96
0.0
Note. *—plantlets less than 1 mm length were fixed.
The highest percentage of rearrangements, 60.8 and 45.5 percent were observed in
the plantlets selected 24 and 27 h after a soakage, respectively.
About 24 and 27 h after X-ray irradiation of seeds, the frequency of rearrange-
ments of chromosomes in plantlets started from maximum. This frequency is decreas-
ing with increasing time from arising of plantlet (see Table 24.1). About 22 h after
irradiation in plantlets fi xed in 0 h, only fi ve plantlets with metaphases were observed.
Their level of rearrangements of chromosomes was high: 50 metaphases contained 78
percent of the rearrangements; 38 h after the treatment eight plantlets were plantlet
and containing 364 percent of metaphases with rearrangements. In all the variants of
plantlets and fi xation, the frequencies of rearrangements per 100 cells were higher than
those of metaphases with rearrangements, which means that it was more than one rear-
rangement per cell (see column of m, % in Table 24.1).
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