Search

Influence of γ-irradiation of barley seeds (Nur variety) at the doses of 8-50 Gy on catalase, pyruvate kinase, glucose-6-phosphate dehydrogenase, and guaiacol peroxidase activities was studied in the seedlings on the 3, 5 and 7 days after germination. It has been shown that activities of the studied enzymes increase in the dose range that causes the growth stimulation in the seedlings (16-20 Gy).

The reaction of barley seeds (Nur and Grace varieties) to γ-irradiation in the dose range of 2-50 Gy was studied. The length and weight of a root, the length of a seedling and germination rate were investigated. The dose range in which we observed stimulation of plant development was evaluated. It was shown that the increase of root and seedling sizes after irradiation of seeds at stimulating doses is associated with the rise in the developmental speed, rather than with their earlier germination. Also the effects of a dose rate, a quality of seeds, humidity and a period of storage on the manifestation of radiation exposure were studied.

The uptake by barley and the distribution between the vegetative and the generative organs of 137Cs, K and Ca was studied when plants were grown on soddy-podzolic soil with the background content of heavy metals and soil polluted with Cd and Co at concentrations significantly above the maximum permissible concentration (50 i 100 mg/kg accordingly). The reduction was found in 137Cs accumulation and removal with barley in ontogenesis under the action of increased contents of heavy metals in the soil, which was caused by their phytotoxic effect.

In a greenhouse experiment effects have been studied the UV-B-irradiation of barley (intensity of biologically active UV-B-radiation was 0.15, 0.29 and 0.45 W/m2) on the morphophysiologic parameters, productivity and reproductive sphere of offsprings of two succeeding generations. It has been shown that along with a decrease in the specific leaf mass and biomass M1-generation plants exhibited an increase in the stem height and assimilative leaf area. The reduction of grain yield in offsprings of the first post-radiation generation was mainly caused by the reduced size in the reproductive organs and by reduced number of caryopsides in a ear. The observed effects were independent of the UV-B exposure levels to the precursors. The aftereffect of UV-B-irradiation for M2-generation plants shown itself as changes in the specific leaf area, less pronounced compared to the precursors, and reduction in the vegetative mass and grain yield, most significant in offsprings of plants exposed to the maximum UV-B levels. Disturbances in the reproductive sphere appeared as reduction in the size of developing grains. The data derived suggest that long-term effects of UV-B-irradiation are possible not only in the first but also in the second generation of impacted plants.

In a greenhouse experiment the development of biomass and grain yield was studied under a long-time combined action of medium-wave UV-radiation and cadmium (exposure levels of the agents were, respectively, 0.65-1.30 W/m2, 5 and 50 mg/kg of soil). The influence of the metal on the UV-radiation induced inhibition of the vegetative mass development was found to be dependent on the duration of stress: with increase in the exposure time the cadmium ability for cushioning negative effects of irradiation decreases. Simultaneously the contribution of the metal and its interaction with UV-radiation to the variability in the observed indicator (biomass) becomes much less significant than that of irradiation. Considerable independent of cadmium concentration reduction in the grain yield becomes evident at a rate of medium-wave UV-radiation intensity of 0.65 W/m2, whereas at UV-radiation exposure levels of 1.30 W/m2 and the heavy metal concentration of 50 mg/kg in soil practically total inhibition of grain productivity occurred. As for grain formation, relative effects of irradiation were somewhat higher than these of cadmium and its interaction with UV-radiation.

It was shown that gamma-irradiation and cadmium nitrate increased synthesis of phytochelatins in roots of barley seedlings. The stimulation of synthesis of phytochelatins in gamma-irradiated plants was shown for the first time. The results obtained indicate more important role of phytochelatins in intercellular metabolism than heavy-metal-binding.

The influence of weak low frequency (50 Hz-10 kHz) physical factors: sound, alternating electric current and impulse light on the germination and root growth rate of barley corns was estimated. Several mechanisms of this effect were proposed: change in penetration of membranes, in enzymes and microflora activity. The dependence between the germination activity of corn and the frequency was represented in the form of universal curve--"Low Frequency Activity Spectrum".

The yield of aberrant cells and their loading with lesions of intercalary meristem of spring barley in conditions of the combined action of 137Cs, heavy metals and 2.4-D herbicide was studied. At simultaneous insertion of 137Cs and Cd into the soil, the type of non-linearity of the yield of aberrant cells was determined by radioactive pollution: in a range of low concentrations the synergistic effects took place, in a range of higher ones the antagonistic effects did. In the presence of cadmium, the severity of radiation induced damage to aberrant cells was significantly less. The interaction in 137Cs-Pb pair had an antagonistic character. The yield of aberrant cells was determined mainly by lead, whereas the radioactive pollution played the main role in loading of the aberrant cells with lesions. At the combined pollution with 137Cs and other contaminants, the antagonistic effects were more pronounced with Pb than with Cd, and further increased with the herbicide, both in the test on frequency of aberrant cells and the test on the loading of aberrant cells with lesions. In case of combination of the chemical agents the non-linear effects in test on loading of aberrant cells with lesions were mainly synergistic, whereas in the test on frequency of aberrant cells they were antagonistic. Only Pb-Cd pair and only in the test on loading of aberrant cells with lesions no significant non-linear effects were found. The results show high rate of the induction of synergistic and antagonistic effects in conditions of the combined action of low concentrations of the investigated agents on plants. These effects substantially determined the yield of cytogenetic disturbances in the studied range.

Dependencies of the yield of cytogenetic disturbances within intercalary meristem cells of spring barley on the soil level of 137Cs (1.48-14.8 MBq/m2), Cd, Pb (2-50 and 30-300 mg per kilogram of the soil) and 2.4-D herbicide (1 or 2 kg/ha) had a non-linear character in the studied range. At low concentrations the yield of cytogenetic disturbances grew faster than at higher ones. Concentrations of lead in soil (at the level of maximum concentration limit) and doses of 2.4-D recommended for agricultural use resulted in the increase in the rate of aberrant cells. The observed rate of cytogenetic disturbances was comparable with the effect of the maximum studied level or the radioactive soil pollution. The heaviest damage to aberrant cells was found in the presence of 137Cs.

The analysis of up-to-date state of the problem of quantitative assessment of cytogenetical effects in the range of low-level doses is presented. The importance of works of N. V. Luchnik is demonstrated for the development of this field of radiobiology. The results of the authors' own experimental and theoretical research on the regularities of induction of cytogenetical damage by low doses of ionising radiation are presented.

The changes in chromatin and DNA of seedling and callus tissues of cereals grown in the Chernobyl NPP zones with contamination levels of 15, 40 and 60 Ci/km2 were studied. Test samples produced by germinating and culturing seed cells of grown in contaminated areas were notable for the content of soluble polydesoxiribonucleotides, amount of DNA damages, DNA distribution over separate compartments of cell nucleus as compared to the control. Analogy between radiation-induced changes in chromatine and processes occurring in cell nucleus senescence was observed.

Antimutagenic activity of triple copolymers of diallyl origin was investigated by animal cell test (mouse bone marrow erythrocytes, 1.5 Gy of gamma irradiation) and by plant cell test (seeds of barley, 5 Gy of gamma irradiation). Effective protection of genetic structure was achieved owing to combination of moderate antimutagenic activity of the polymer matrix and scavenging ability of sterically hindered phenols in the polymer side chain.

Genotoxic effects during microsporogenesis and gametogenesis were studied in barley of the waxy strain grown on 3 experimental plots situated in the region of the Chernobyl disaster (plot 1 in the town of Chernobyl, plots 2 and 3 in the town of Yanov, 3 km away from the damaged power plant). It was determined that an increased level of radionuclide pollution and chronic irradiation during ontogenesis results in higher incidence of meiotic disturbances and abnormalities during formation of the male gametophyte. Incidence of waxy reversions in pollen grains depends on the activity of radionuclide pollutants as well. We suggest that selection affecting both diplont and haplont forms will provide for the absence of significant aberrations in subsequent plant generations.