The Assessment of Maize Plants Adaptation to Cadmium Chloride Influence by Through the Radiocapacity Factor

Pchelovska S. A.

BIOLOGY

Scentific article

An important objective of modern radiobiology is the study of effects caused by the action of various stress factors on living organisms, as well as the recovery processes and adaptation to stressful influences. Previously, we proposed a new approach to assessing the state of biotic component of ecosystem under the action of harmful factors – by the behavior of radiocapacity factor. Radiocapacity factor – a dimensionless quantity, which is defined as the maximum amount of radionuclides, which by its exposure dose is not yet able to violate the basic functions of the biota: the ability to maintain the biomass and condition habitat. In experiments on water culture of maize plants it was shown that the radiocapacity factor – is the convenient and adequate indicator of the state of biotic components of the ecosystem model (maize plants). Changing the radiocapacity factor under the action of radiation and toxic factors (γ-irradiation and introduction of cadmium chloride into the nutrient medium) correlated with changes in growth indicators. Reducing of the radiocapacity factor values of plants give evidence of worsening of their sorption activity concerning specially introduced tracer 137Cs, what, in turn, said about the impairment of state of plants. According to the experimental data received, the radiocapacity parameter proved to be very sensitive to the different stress agents on biota and could anticipate in advance the trends of growth reactions for biological objects. The aim of this work was to apply this approach to study the phenomenon of plant adaptation to the action of the toxic factor – namely, introducing into the habitat of cadmium chloride solution. Investigations were carried out using the method of assessment radiocapacity factor, the essence of which is to determine the sorption activity of maize plants facilities share (percentage) of radioactivity which remains in culture medium after a defined period incubation of the object on it. The radiocapacity factor (Fb) for each of the experimental variants was calculated as follows: Fb = 1-Аі/А0; where Aі – activity of the nutrient solution in the i-th moment of observation (it was measured directly during the experiment), A0 – activity of the solution at the initial time (specially introduced activity). Normalization of the calculated values of Fb was carried out by dividing the value into the corresponding i-th moment of observation (Fbі) on the Fb value for the control (Fb contr.) and multiplying by 100 %: Fb norm. = (Fbі/ Fb contr.)×100 %. Thus obtained estimates of sorption activity were then used to construct the radiocapacity factor of plants dose and time-dependences. A standard scheme for the study of adaptation whereby maize plants were subjected to the first impact of adapting dose/concentration (AD), and after some time (Δt) applied a test dose/concentration (TD), was used. The concentration of cadmium chloride (CdCl2), providing some stimulation on the growth parameters and indicators of absorption activity of substances from the solution – radiocapacity factor, was applied as a modifying influence. This concentration of CdCl2 was chosen as a result of studying of the concentration dependences of growth and radiocapacity parameters. So adapting dose/concentration 1 µM and test dose/concentration 25 µM were chosen and time between were 4 h and 24 h. The experiment was carried out thus to be able to simultaneously observe the absorption activity water culture of plants and determine the growth response of plants to the action of different concentrations of cadmium chloride. The dependence of adaptation on the time interval between the test and adapting concentrations of cadmium chloride was revealed. Particularly, adaptation was observed at entering “test concentration” 25 µM after 24 hours after the adapting concentration 1 µM CdCl2. The effect of sensitization on the growth and absorbing characteristics of plants of salt CdCl2 when entering the test concentration within 4 hours after adapting it is observed. It is shown that the radiocapacity factor is adequate, a sensitive indicator manifesting the response of plants to stress influence in the conditions of adaptive schemes impact using.

adaptation, radiocapacity factor, cadmium chloride, maize plants

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«Bulletin of problems biology and medicine» Issue 3 part 3 (112), 2014 year, 35-38 pages, index UDK 57. 017. 32 : 57. 044