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Saimnazarova Charos Yuldashevna, Ph D., student, the Department of Agobiotechnology, Toshkent State Agrarian University E-mail: saimnazarova.charos@gmail.com Djumaniyazova Gulnara Ismailovna, professor, DSc in biology, Academy of Sciences RUz,
Institute of Microbiology Narbaeva Khurshida Saparbaevna, DSc in biology, Academy of Sciences RUz Institute of Microbiology E-mail: saimnazarova.charos@gmail.com
EFFECT OF FUNGICIDES AND MICROBIOLOGICAL PREPARATIONS ON SOIL BIOAGROCENOSE
Abstract: Biopreparation of complex action Rizokom-2 in comparison with chemical fungicides and microbiological preparation Baikal EM-1 positive influenced on pH of soil solution, balance of soil microbial community and biogenic elements.
Keywords: wheat, fungicides, microbiological preparations, soil, microbial and agrochemical composition.
Introduction
Currently, the productivity of wheat, as a rule, low. The reason for this is a significant decrease in soil fertility due to the deterioration of the water and nutrient regimes of the soil, an increase in the weediness of crops and an intensification of the infectious background. The main prerequisites for reducing the yield of wheat are unfavorable conditions of mineral nutrition and non-compliance with the system of plant protection against diseases.
It is known that soil elements such as nitrogen, phosphorus, potassium, calcium, magnesium, etc. have a beneficial effect on the productivity of winter wheat. Nitrogen is part of the molecule of chlorophyll, vitamins, alkaloids, increases the green (vegetative) mass of plants and yield. Phosphorus plays a decisive role in photosynthesis, the transfer of energy and hydrogen (respiration), rooting, accelerates the transition of plants to the reproductive phase of development, increases the yield, quality and resistance of plants. Potassium positively affects the resistance of plants to drought, low temperatures, pests and fungal diseases, allows plants to use water more economically and more efficiently, increases the transfer of substances in the plant. Calcium is involved in water, carbohydrate and nitrogen metabolism in the plant, regulates metabolism, water and physiological balance of the cell. Calcium is also necessary for the plant to form nucleic acids, photosynthesis and energy metabolism are closely associated with it. Magnesium participates in the biosynthesis of chlorophyll, enhances the absorption of potassium by the root system. However, in many soils these nutrients are inaccessible. Both the lack of nutrients and their excess causes stress in crops of
crops, reducing their potential productivity. Particularly great is the effect of imbalance of nutrients in critical periods of development of grain crops: bushing, flowering, grain filling.
Lack or excess moisture, diseases and pests of plants and soil fertility are the main factors that limit crop yields. To achieve a balanced agriculture, it is necessary to pay attention to such processes as the biological transformation of nutrients, and also to remember how important it is to maintain biodiversity in ecosystems.
The existing methods of farming, such as the introduction of fertilizers, especially mineral fertilizers, limit the biodiversity of rhizobial bacteria. In addition, the roots of plants from balanced agroecosystems contain more bacteria that suppress diseases than the roots of those from highly-equipped agro-cenoses [1].
At present, in connection with the increasing anthropogenic impact on the soil and, as a consequence, the deterioration of the ecological situation, the development of biotech-nological methods for optimizing the growth of agricultural plants, including the development and introduction of highly productive strains of microorganisms, the use of which is environmentally friendly, has become very important. Numerous experiments show that associative and symbiotic microorganisms due to complex action on plants are able, and sometimes significantly, to increase the productivity of the latter [2].
One of the ways to increase the productivity of crops is the optimal selection of complex treatment of seed. Unfortunately, chemical plant protection products among the anthropogenic factors are characterized by the greatest pressure on the populations of phytopathogens in agrobiocenoses.
Some disinfectants have a negative effect on the germination of seeds, the growth and development of plants, which ultimately affects the yield and quality of products.
In order to increase the yield of wheat, it is of great importance in the delivery of properly developed and properly organized crop cultivation technology, as well as new methods of presowing seed treatment with biological products that stimulate plant growth, improve seed quality of seeds, increase productivity and yield.
At present, the role of non-pathogenic microorganisms in preserving soil fertility, increasing the yield of various crops, obtaining environmentally safe products and, ultimately, in normalizing and improving people's livelihoods is being intensively studied [3].
The obtained data also indicate that effective microorganisms are also able to purposefully interfere with the circulation of carbon, nitrogen, phosphorus and other nutrients. Soil microorganisms ensure the restoration of soil fertility, prepare the nutrient medium and transfer it from the soil solution to the root system, and process flora and fauna into useful soil components. Therefore, in technology of cultivation of agricultural crops, it is necessary to give due attention to soil microflora.
In the laboratory of soil microbiology of the Institute of Microbiology of the Academy of Sciences of the Republic of Uzbekistan within the framework of the applied project FA-A6-T215 (2012-2014) a biopreparation of complex action Rizokom-2 was created on the basis of an association of 3 local effective strains of phosphorus and potassium-mobilizing wheat rhizobacteria of g. Bacillus.
The active basis of the biopreparation are local active strains of wheat rhizobacteria having the following polyfunctional properties: phosphorus and potassium mobilizing ability, destructive activity to organochlorine pesticides, root-forming and growth-stimulating activity, increasing plant immunity, soil fertility and wheat productivity. The new biopreparation is intended for pre-sowing seed treatment in order to optimize the conditions of root nutrition ofwinter wheat [4].
Within the framework of the innovative project I5-FA-0-19521 (2013-2014) a biotechnology has been developed for obtaining a Serhosil biopreparation based on green microalgae g. Scenedesmus as foliar application to increase crop productivity [5].
In connection with the foregoing, the main purpose of the research was to study the effect of chemical fungicides and microbiological preparations on the soil microbial community, the agrochemical composition of soils, the incidence level and productivity of wheat.
The object of the research was: pure, non-treated seeds of Bardosh variety of winter wheat, chemical fungicides Bahor
(Uzbekistan), Celest Top (Italy), microbiological fertilizer Baikal EM-1 (Russia), biopreparation Rizokom-2 (Uzbekistan, IMB), soil of the experimental site of the Institute genetics and experimental biology of plants of the Academy of Sciences of Uzbekistan, biologic Serhosil. Field experiments with winter wheat conducted on the background of NP200 kg/ha and were carried out in 3-fold replication according to the following scheme of variants:
1. Control - traditional wheat sowing (dry seeds);
2. Experiment- seed treatment with fungicide Bahor;
3. Experiment - seed treatment with fungicide Celest Top;
4. Experiment - seed treatment with microbiological fertilizer Baikal EM-1;
5. Experiment - seed treatment with biopreparation Rizo-ko m-2 + 3 time foliar application of biopreparation Serhosil.
Pre-sowing treatment of wheat seeds with chemical fungicides and microbiological preparation Baikal EM-1 was carried out according to the instructions, by biopreparation RIZOKOM-2 with titer of 6x107 CFU/ml during the 1 hour in field conditions, by following drying the seeds in natural conditions and sowing on the field.
The microbial community of the soil was studied according to the generally accepted method of D. G. Zvyagintsev [6].
Agrochemical analyzes of soils were carried out according to methods generally accepted in agrochemistry. The value pH - the hydrogen index is measured by a standard chloride-mercury electrode with automatic temperature compensation. In soil samples, the pH value is measured in an aqueous suspension of1:5. The humus content was determined by the Tyurin method, the determination of the total forms of nitrogen and phosphorus was carried out according to the method of Ginzburg et al., The content of mobile nitrogen N-NH4 and the mobile phosphorus - P2O5 - by calorimetric method, exchange potassium K20 - by flame photometry.
The degree of soil salinity was determined by analyzing the water extract. The method is based on the content of wa-ter-extractable salts in the soil (TSS). Cations and anions were determined using a gravimetric method. The content of toxic salts was calculated by the method of determining hypothetical salts in mg. eq/100 g of soil [7].
The results of the research and their discussion
Soil samples of the initial soil were selected before sowing of winter wheat seeds. The salt and agrochemical composition was studied (Tables 1-2), as well as the microbial community of the initial soil (Table 3).
As can be seen from (Table 1), the initial soil before sowing wheat is non-saline, but with predominance of Ca and Mg sulfates, with a slightly alkaline reaction of the soil solution - 7.7.
Table 1.
Place of sampling Degree of salinity in ЕСе, dS/m Type of salinity рн
Initial soil 0.79 not saline, prevalence of sulphates Ca and Mg: CaSO4-37%, MgSO4-29%, Na2SO4-3%, NaCl-16% 7.7 Slightly alkaline
Table 2.- Agrochemical analysis of soil:
Humus content:
Name of the sample Humus,% Carbon of humus,% (G,%) Evaluation of the provising
Initial soil 1.03 0.60 medium-sized
According to the content of gross (total content) forms of nitrogen - the initial soils are poor. According to the availability of mobile (assimilated by plants) forms of nitrogen - very low.
Nitrogen content:
Name of the sample Gross forms of nitrogen,% Evaluation of the provising Mobile, assimilable to plants forms of N-NH4, mg/kg Evaluation of the provising
Initial soil 0.068 oor 15.6 very low
According to the content of gross (total content) forms of phosphorus - the initial soils are rich. According to the availability of mobile (assimilated by plants) forms of phosphorus - the average.
Phosphorus content:
Name of the sample Gross forms of phospho-rus % Evaluation of the provising Mobile, assimilable to plants forms of Р2О5, mg/kg Evaluation of the provising
Initial soil 0.237 rich 31.2 middle
According to the content of gross (total content) forms of potassium, the initial soil is very poor. According to the availability of mobile (assimilated by plants) forms of potassium - low.
The content of non-toxic salts in the soil is 52% of the total amount of salts, the content of toxic (easily soluble and harmful to plants) salts is 48.5% of the total amount of salts. Among the toxic (harmful) salts, magnesium sulphate - MgSO4, which is 29% of the total amount of salts and 60% of the amount of toxic salts, is predominant.
Potassium content:
Name of the sample Gross forms of phospho-rus % Evaluation of the provising Mobile, assimilable to plants forms of K^, mg/kg Evaluation of the provising
Initial soil 0.615 very poor 118 mean
Salt content,%
Name of the sample Ca(HCO3)2 CaSO, 4 Amount of non-toxic salts MgSO4 Na SO, 24 NaCl MgCl2 Amount of toxic salts Amo-unt of the total salts
Initial soil 0.016 0.038 0.054 0.030 0.003 0.016 - 0.050 0.103
Microbiological monitoring included the study of the number of major agronomically important groups of soil microorganisms involved in the nitrogen, phosphorus and potassium cycle, as well as other microelements in the soil-ammonifiers, oligonitrophils, phosphorus mobilizing bacteria, actinomycetes, and micromycetes in the arable (0-30 cm) layer of parent soils.
According to microbiological indices - in the initial soil only ammonifiers and actinomycetes are normal, phosphorus mobilizing bacteria are lower by 2 orders of magnitude, oligonitrophils are lower than the norm by 1 order, micromycetes are above the norm by 1-2 orders of magnitude, which may indicate a high content of micromycetes in the initial soil, among There are also pathogenic fungi that cause plant diseases (Table 3).
As can be seen from the data presented in Fig. 1, the number of ammonifiers was at the same order of magnitude and was from 8.2 to 9.9 lg CFU/g soil. The number of oligonitro-phils increased by 1 order (from 6.7 to 7.1 lg CFU/g soil), phosphomobilizing bacteria - by 2 orders (from 6.6 to 8.1 lg CFU/g soil) only in the variant with Rizokom-2. The num-
Table 3.- The number of main groups of soil microorganisms in the original soil before planting wheat (CFU/g of soil)
ber of actinomycetes was at the same level in the original soil and in variants using microbiological preparations (5.4-5.5 lg CFU / g soil) and decreased by 1 order in the control and in variants using chemical fungicides (from 5.4 to 4.0-4.3 lg CFU/g of soil).
Name of the sample Ammonifiers Phosphorus mobilizing bacteria Oligonitro-phils Micromycetes Actinomycetes
Initial soil 1.9 x 108 6.0 x 106 6.9 x 106 1.5 x 104 3.7 x 105
Figure 1. Influence of chemical fungicides and microbiological preparations on the number of soil microorganisms in soil under wheat (lg CFU/g of soil, arable horizon, 0-30 cm)
Figure 2. The effect of chemical fungicides and microbiological preparations on the content of humus and dense residue in the soil under wheat during vegetation (%, arable horizon, 0-30 cm)
During the growing season (the middle and the end of the growing season), the microbial community and the agrochemical composition of the soil were studied using chemical fungicides and microbiological preparations during the pre-sowing treatment of wheat seeds ofthe Bardosh variety. Figure 1-4 shows the end-of-vegetation data in comparison with the initial soil.
The humus content in the arable layer of soil under wheat was reduced in the middle of vegetation by 0.08% only in the variant using Rizokom-2, but by the end of the vegetation the humus content increased to the level of the initial value. This fact indicates that under the action of the Rizokom-2 biological preparation, oligonitrophiles and phosphor-mobilizing bacteria ac-
tively multiplied in the soil, due to which carbon and phosphorus were released from humus and assimilated by plants (Fig. 2 A). The content ofthe dense residue in the soil most decreased from the initial value by 0.02% in the version using Rizokom-2, which indicates a decrease in the level of soil salinity (Fig. 2 B).
The study of the content of toxic and non-toxic salts in the soil under wheat also showed their decrease only in the variant with the use of Rizokom-2, where the amount of salts decreased by 0.03%, and in the variant with the use of chemical fungicides - increased by 0.02-0.03%, in the variant with application of Baikal EM-1 the amount of salts did not change in comparison with the initial soil and with the control (Fig. 3).
Figure 3. The effect of chemical fungicides and microbiological preparations on the content of salts in the soil under wheat (%, arable horizon, 0-30 cm)
Figure 4. The effect of chemical fungicides and microbiological preparations on the content of mobile forms of nitrogen, phosphorus and potassium in the soil under wheat (mg / kg soil, arable horizon, 0-30 cm)
The content of mobile nitrogen in the soil increased by the end of the vegetation period by 6.2-7.6 mg/kg soil in variants
with the use of chemical fungicides, by 9.4 mg/kg soil - in a variant using Baikal EM-1 and by 16 mg/kg of soil - in the
version using Rizokom-2 in comparison with the original soil and with control. The obtained data indicate that the use of microbiological preparations has a positive effect on the content of mobile nitrogen in the soil. The best option was the application of the biological product Rizokom-2.
The content of mobile phosphorus in the soil by the end of the growing season decreased by 6.7-9.9 mg/kg soil in variants with the use of chemical fungicides, by 10.9 mg/kg soil -in the variant with Baikal EM-1 and by 3.3 mg/kg soil - in the version with the use of Rizokom-2 in comparison with the control. The obtained data indicate that when using chemical fungicides and Baikal EM-1 by the end of vegetation in
the soil, the content of mobile phosphorus is much reduced, using Rizokom-2 - the decrease is in significant, which is a positive moment.
The content of mobile potassium in the soil by the end of vegetation decreased by 27-34 mg / kg soil in variants with the use of chemical fungicides, by 62.0 mg / kg soil - in a variant using Baikal EM-1 and 48 mg / kg soil - in variant with application of Rizokom-2 in comparison with the control. The obtained data indicate that the use of chemical fungicides has a negative effect on the content of mobile potassium in the soil, while the use of microbiological preparations has a positive effect (Fig. 4).
Figure 5. Influence of chemical fungicides and microbiological preparations on soil pH under wheat during vegetation of plants (arable horizon, m 0-30 cm)
A study of the pH of the soil revealed that during the vegetation of wheat the pH of the soil solution rises from 7.7 to 8.2-8.4 during the growing season, both in the control and in all experimental variants, with the exception of the variant with Rizokom-2, where soil pH rises only in the middle of vegetation, but decreases significantly by the end of vegetation to 7.8 and becomes at the same level as the initial value (Fig. 5).
Thus, on the basis of the results obtained to study the effect of chemical fungicides and microbiological prepara-
tions on soil bioagrocenosis - the microbial community and the agrochemical composition of soils under winter wheat during the growing season revealed a positive effect of the RIZOKOM-2 complex action on the pH of the soil solution, the balance of the soil microflora in the use of beneficial microorganisms and the balance of biogenic elements - nitrogen, phosphorus and potassium. The parameters of the amount of salts and the content of the dense residue decreased by the end of the vegetation period by 0.03%.
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