Procedures for biological testing with representatives of the family LemnaceaeIt is possible to conduct biotests using species of the family Lemnaceae at several levels:
Equipment for conducting the testing:
Inhibition of phototaxis.
Because of positive phototaxis, chloroplasts in the cells of parenchyma on the upper side of the frond and part of the thallus were located in the upper wall of cells in the epistoform position, i.e., perpendicular to the light beam. Without moving the preparation, a strong illumination was directed on the subject in the microscope, as strong as possible without damaging the cells.
After 10 minutes the illumination of the subject was decreased to a
level convenient for observation, and under 400-power magnification the
number of chloroplasts in the epistoform position were counted. In the
control (distilled water) the number of epistoform chloroplasts is minimal,
since the majority of the chloroplasts will move away because of the negative
phototaxis to the parastoform position, being moved against the side walls
and being turned with their thin edge to the light beam.
Fixation of morphological changes.
Method of calculating the realization of reproductive potential.
During the time of exposure of the fronds in the control and in each concentration, the total number of fronds are counted, including maternal individuals and fronds which have separated from the maternal individual.
In the control and in each concentration the coefficient of an instantaneous
increase in the population (r) is calculated on the basis of theresults
where N0 - initial number of fronds; Nt - final number of fronds; t - duration of experiment (twenty-four hours).
Further for each t is calculated the frond number doubling time (t of
The index of change of the frond number doubling time for the duckweed
in the solutions being investigated with respect to the control, is expressed
in percentages (Dt):
Dt indicates the quality of the tested aqueous solution. A deviation
of more than 20% from the doubling time of the control is considered statistically
significant. Deviation to the side of decrease during the toxicological
analysis shows the degree of the action of toxicant, with biomonitoring
- indicating a decrease of the eutrophication of water or the presence
of toxicants. In exceptional cases in biomonitoring it is possible to observe
an increase in growth rate as a response to increasing concentrations of
the test solution, as in the case of an increase in eutrophication.
Method of vital staining.
Studies have been conducted in the prolonged multifactor stationary experiment since 1992, placed in the experimental field KGAU.
Soil of the test area: light, super-power, low-humus black soil.
The stationary multifactor experiment examines the following factors: Factor A - fertility of the soil; Factor B - system of fertilizers; Factor C - the system of plant protection, and factor D - the system of the basic cultivation of the soil. In the experiment four models of the levels of the fertility of soil are created on the basis of the existing normative indices due to the introduction under the first culture of crop rotation (the sugar beet) of organo-mineral fertilizers. For creating the soil background A1 - 200 kg/ha P2O5 and 200 T/ha of bedding manure were applied. For creating the background A2 - the doses of fertilizers were doubled, and for background A3 - they were tripled. A0 was the natural background (Table 1).
Experimental variants of agro-ecological monitoring on sowings of winter wheat of the type of fathers (year 2001)
The second factor studied in this stationary experiment was the system of fertilizers (Table 1.). The ranges of the fertilizer applications were determined on the basis of balance method, taking into account the planned productivity for the required quality of production, the assigned rates of soil fertility, and favorable state of environment.
The system for protection of plants from pests, disease and weeds was the third factor studied in the experiment. In all experimental variants seeds were disinfected using a insecticide-fungicide mix.
The system of the basic cultivation of the soil was the fourth factor studied in the experiment. In the case of this experiment, the cultivation recommended for this region was adopted.
During the development of present program the basis was a multifactor experiment design (4*4*4)*3. The objective was to study the fertility of the soil, the system of fertilizers and the system of plant protection at doses 0,1,2,3 using the recommended soil cultivation.
The area of the experimental plot: 4,2 m * 25,0 m = 105 m2, stock-taking 2,0*17,0=34 m2. Repetition of the experiment - triple. Each field of crop rotation had 144 plots (72 plots*2 blocks) and occupied an area of 1,75 ha (160 m*109,2 m).
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