Soil Detoxication by the Means of Activated Carbon in Breeding Process

. The paper describes results of vegetative tests of activated carbon as a detoxiсant of herbicide remains in soil on eight varieties of summer rapeseed. The tests were performed with the purpose to align soil fertility on different breeding and test sites. The research is based on attempts to apply coal absorbent as a means of soil detoxication to neutralize herbicides remains in the process of oilseed brassica crops breeding. Several summer rapeseed varieties were used as research objects. Similar approaches have not encountered in literature references available.


Introduction
Variety testing (pre-test, competition, ecological) is the essencial part and logical outcome of breeding process. The best varieties (productivity-and qualitywise) further pass to State Variety Test Commitee according to the results of variety testing.
The tests compare genetically different plants exposed to the same conditions to provide varieties' proper evaluation. The agrotecnical conditions such as soil fertility, cultivation technology, seeding ratio and depth should be identical. The only difference to be considered is the response of different genotypes to the same set conditions. The only subject of testing is a variety (a certain genotype). The test results can be recognized as successful and adequate only in case if all the principles described above are followed [1].

Theory
Aligning soil fertility on the test site is prior to the researcher. Although, the uncontrolled influence of pesticide remains in soil on variety yield evaluation has been recently observed. This occurs when genotypes respond differently to this factor. Varieties with high herbicide tolerance indicate higher yield during breeding tests. At the same time, presence of pollutants in soil create unfavorable vegetation environment for other varieties, suppressing their genetic potential.
It is quite random to come across soils with either systematic or accidental fertility variation. Most likely it is both.
Test results regarding yield and its quality may be different from true figures due to certain failures. Researcher faces 3 kinds of failures while performing tests. Those are accidental, systematic and rough. They may have different causes including presence pollutants in soil.
Systematic failures don't influence comparability of different test options (they vary in the same direction), though may slightly affect tests results. It is true only in case if genotypes' response to this stress factor is the same.
Pesticide remains in soil reduce genotypes' yield capacity and distort the comparison of different varieties (hybrids). While performing breeding tests, only genotypes must differ, though all the other conditions should be identic ("principle of the single difference"). In this regard, only field test results that do not contain one-sided errors should be used for results mathematical processing and making reasonable conclusions.
Soil detoxication with the use of absorbent materials may be applied as the way to counter the impact of herbicide and pesticide remains. The positive impact of activated carbon application for protection of various crops from the affects pesticides and herbicides has been discovered and studied in the world's leading research enterprises. [2][3][4][5][6][7][8][9][10][11][12][13][14].

Materials and methods
A mixture of soddy podzolic soils with sand and rotted manure at a ratio of 1: 1: 1 was used as a soil substrate. According to the number of test options, 72 soil samples 3 kg each were placed in plastic bags. 400 ml of tap water were added to each sample because the prepared soil in the bunker had not been hydrated. 24 hours later soil samples were poured into trays and treated with the pollutant (herbicide) on OP-5 unit (central atomizer, liquid volume for spraying 10 ml). The treated soil was stirred thoroughly and placed back into plastic bags.
Zinger herbicide (ZH) was applied as a pollutant at application rates of 2.5 and 5.0 g/ha (ZH-2.5 and ZH 5.0 further in the paper). The pollutant (60% metsulfuron-methyl) was chosen due to the fact that it is a typical representative of the latest generation of herbicides, belonging to sulfonylurea class. Sulfonylurea-based herbicides have unique physiological activity and are widely used in agriculture for weed control in cereal crops. However, they tend to preserve in soil for long and agricultural crops are quite sensitive to their remains. In addition, long-term experiments with herbicides of this class have indicated consistent increase of plant resistance to it (from 0.001% up to 60.5% in 5 years).
The samples that have been exposed to neither herbicide nor activated carbon were taken as standard. Naturally, samples that have been treated by either herbicide or activated carbon were also presented.
The pots were placed in artificial climate chamber (ACC) for 15 days with day temperature of 20 °C and night temperature of 16 °C and day and night length 16 and 8 hours respectively; illumination of test plants during the day period was 20000 LK. The plants were watered daily to keep humidity level at 60-70%.
In 15 days the plants (6 pieces in each pot) were cut for standard and treated samples to be weighed and compared. Pots with standard and treated plants were photographed before putting results on record (photo 1,2).
Weight loss of treated plants relative to standard ones was calculated by the formula:

( )
where B -weight loss of treated plants relative to standard ones; A -average treated plant weight; K -average standard plant weight. The results are presented in Table 1, Photo 1 and 2.

Conclusion
Comparative tests results of activated carbon application as Zinger herbicide detoxicant in several options have revealed variations in response of different summer rapeseed varieties to the negative herbicide impact. Tests results also indicated a relatively high tolerance of Arbalet, Ratnik, Rif and Bulat varieties to the negative herbicide impact. These varieties are preferable to be used in crop rotations with an intensive herbicide application.