Reaction to pesticides
|Lemnaceae began to be used for the first time as phytotesters for testing
the pollution/ contamination of water by pesticides. As the correct
estimation/evaluation the indices were used: the coefficient of growth,
length and a quantity of roots, the area of fronds,
the reaction of photosynthesis and other physiological and morphological characteristics.
In the course of the set experiments according to the capability for growth and the viability under the conditions of the action of different preparations the following relationships were revealed: Lemna minor shows a sudden and strong reaction, which is continued for a while, after which it ceases to react to the toxin; therefore it can be considered a Type 1 Bioindicator (a bioindicator that shows a sudden and strong reaction) according to the classification; Lemna trisulca reacts to contaminants more intensively, however, the distinctive maximum reaction gradually attenuates and therefore it can be categorized as a Type 4 Bioindicator (under the effect of the contaminant the reaction of the bioinidicator gradually becomes of ever of more intensive; however, after reaching/achieving a maximum it gradually attenuates); with Spirodela polyrhiza after an immediate, strong reaction, the response dampens, first sharply, then gradually, which is characteristic of a Type 3 Bioindicator (after immediate, strong reaction of the bioindicator, it is observed to dampen, first sharply, then gradually).
Thus, on the basis of the carried out observations the forms being investigated can be identified as bioindicators of different types.
Use of such qualitative indices as specific pigmentation and specific reaction gives the possibility to estimate the specific individual reaction of bioindicators to each separate herbicide. For the index specific pigmentation we have isolated the following criteria:
In addition to this the following types of specific reaction were isolated:
In the last stage of work for us it was necessary to analyze the changeability
of all available measurable characteristics. In the work of Wang
(1991) where the basic factor was the growth process, the methods of the
statistical analysis were used. In our work we used the methods of
multivariate statistics, where the influence of each factor can be investigated.
Three-factor analysis of variance for the variability of the coefficients
of instantaneous growth made it possible to reveal statistically reliable
differences on the factors "form", "herbicide" and "concentration" with
the portions in general/common variances of 61,9% and 10%, respectively.
Interaction of factors was not considered, since data were organized into
the nonrepetitive dispersion complex. As can be seen from the results
of analysis of variance , according to this criterion it was possible to
reveal high species specificity (61,0%), which gives grounds for investigating
this index for each form separately.
Then we obtained the table of average values by the index the "coefficient
of instantaneous growth" (Table 3). This seemed interesting, since
by this indication the factors "form", "herbicide" and "concentration"
were identified as statistically reliable differences.
It is evident from table 3 that the differences are observed only between the lowest and highest by concentrations. The difference between the forms is present. Moreover Lemna minor is characterized by the greatest coefficient of instantaneous growth. The herbicides gradil and kharnes possess the maximum phytotoxicity (inhibiting the increase in fronds), while Roundup and burifena are of average phytotoxicity. Poast, acryl- M and bazagran inibit growth less. The appearance of these three groups can explain, on one hand, the degree of phytotoxicity of the tested preparations and, on the other hand, the basic requirements, presented by the herbicides - degree of specificity during the destruction of weeds in the environment (K. Fedke, 1985).
Two-factor analysis of variance revealed, what in the structure of the changeability of horizontal chloroplasts was represented only correlation with the factor of herbicide. The differences between the forms, and also the effect of interaction are acknowledged to be statistically uncertain.
Concentration and Herbicide: The results of three-factor variance analysis revealed statistically reliable differences for the factors of concentration and herbicide, constituting 15% and 23% of the variance, respectively, and it was revealed that the effect of their interaction constituted 34% of the variance.
Species: Statistically reliable differences were not identified between the species. Effects of the following interactions also were not detected: concentration - form, herbicide - form, and concentration - herbicide - form.
The percentage of the damage related to statistically-reliable differences was not revealed according to the indices, which can be connected to similar insignificant "damaging action" of all herbicides there and with the fact that herbicide concentrations apparently were distant from their PDK for the species data.