The postradiation (therapeutical) treatment is one of the most appropriate effects for the regulation of all the physiological processes, particularly, repair systems. The exogenic activation of intracellular processes modifies, to a great extent, the radiation damage, increasing the potential of the cell safety system with the help of somatical protection.
Table 1. Biometrical characteristics
|Variances||Plant height||Leaf length||Leaf width|
|g + Crossing||79.19±2.16*||52.54±0.77||5.01±0.09|
|g + Phytostim||74.77±1.96||51.39±0.81||4.85±0.09|
|g + EF||74.11±1.91||50.89±0.82||4.98±0.09|
|g + EHF||78.93±1.94*||51.60±068||5.03±0.08|
|g + Crossing||137.29±2.31**||59.84±1.00*||6.23±0.12|
|g + Phytostim||118.83±4.52||51.37±1.53||5.66±0.17|
|g + EF||127.59±2.97||55.18±1.21||5.90±0.16|
|g + EHF||135.40±2.52*||59.42±1.09||6.18±0.12|
The difference with the radiated control is significant: * - 5%, ** - 1%.
The studies carried out show a possibility of overcoming the problems of radiation mutagenesis in higher plants. The biometrical characteristics of the first generation plants express in their physiological condition the treatments studied (Table 1). The postradiation treatment with the synthetic growth regulator "Crossing" and exposure to electromagnetic field of an extremely high frequency (EHF) mitigated the damage effect and enhanced plant habitus in the two stocks under study, MK-01 and 19-3-3, while the radiation doses were within the lethal ones (250Gy). The biometrical indices of the plants exposed to postradiation treatment with the biostimulator "Phytostim" and the electric field (EF) of the current at an industrial frequency did not differ from the radiated control.
The findings of the cytological studies are summarized in Table 2. The number of aberrant cells in the control corresponds to the experimental data of other authors and does not exceed 1%, which proves a genetic stability and developed safety system of the 19-3-3 stock. The aberration number of the chromosome material upon radiation made 20.74%, which indicates serious damage of the genetic plasma. Among all the treatments studied, only one contributed to the activation of repair processes; i.e. the postradiation treatment with "Crossing" - 15.94%. However, the percentage of chromosome damage exceeds significantly the control in this treatment, which leads to the suggestion that a high percentage of morphogenetic modifications caused by the chromosome aberrations can be expected. The studies on the elimination of the damaging action of the postradiation treatment for the trait of the number of sterile pollen grains are given in Table 3. The samples of pollen grains were collected on four dates.
Table 2. The cytological studies on the action of postradiation treatments. (Ikhim, Scorpan, Lysikov, MNL 73, 1999.)
The exogenic factors applied after radiation induce the catalysis of repair reactions causing mistakes in the repair system action. The change in the physiological condition of the damaged plant organism must not lead to the elimination of the apical dominance, otherwise it will result in regeneration recovery or dedifferentiation of tissues. But in both cases, these lead to elimination of mutant population of the apex initials. The observation over M2 showed that this combined effect increased not only the number of specimens in the offspring, but the range and percentage of mutant forms.
Table 3. Sterility of pollen grains.
|Variances||I date, %||II date, %||III date, %||IV date, %|
|g + Crossing||12.8||14.7||19.9||22.8|
|g + Phytostim||15.4||18.3||21.8||27.6|
|g + EF||16.0||19.1||27.2||26.0|
|g + EHF||17.7||21.5||18.8||21.7|
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