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UDC 633.34:631.559.2:631.461.52:631.461.74
INCREASE OF EFFICIENCY OF SYMBIOTIC SYSTEMS IN AGROCENOSES OF NORTH ECOTYPE SOYA VARIETIES
Parahin N.V., Academician of the Russian Academy of Sciences, Professor Kuzmicheva Y.V., Candidate of Agricultural Sciences, Senior Lecturer Petrova S.N., Doctor of Agricultural Sciences, Assistant Professor Botuz N.I., Candidate of Agricultural Sciences, Assistant Professor Tychinskaya I.L., Post-graduate Student, Junior Research Scientist Orel State Agrariant University, Orel City, Russia E-mail: [email protected]
ABSRACT
The investigations on studying the ACC-utilizing bacteria influence on the efficiency of symbiotic systems of different soya varieties are carried out. The stimulatory effect of introduced microorganisms on the formation of nitrogen-fixing symbiosis of plants and local
populations of nodule bacteria is proved. Thereby the yield capacity increment reached
2,4...6,3 dt/ha. Thereat the efficiency of the used biopreparations mainly depends on the variety.
KEY WORDS
Soya; Variety; Plant-microbial systems; ACC-utilizing bacteria; Symbiotic nitrogen-fixing.
The cropping capacity growth is impossible without soil microflora, which intensive life activity mainly determines soil fertility. More than that forming the associations and symbioses with cultivated plants, microorganisms provide their water and mineral nutrition, adaptation to abiotic stresses and also pathogens and phytophages protection allowing maximum realization of biological potential at resource expenditures decrease [1, 2, 3, 4, 5]. The most important for agriculture integrated plant-microbial systems (PMS) are the legume-rhisobia, endomycorrhiza and growth stimulating symbioses [6] that being taken separately or in complex are typical only for leguminous crops in connection with their enhanced symbiotrophicity and habitat forming function. At the same time the formation of the effective symbioses is provided by the complex of abiotic and biotic factors including plant varietal individuality and it is possible only at creating favorable conditions for microbiological soil activity that are not often observed in intensive agro technologies.
In this connection the search of methods and ways of increase of symbiotic systems efficiency in agrocenoses of leguminous crops is significantly vital; at this the application of microbiological approaches in connection with intensification negative effects is of special interest.
That is why the goal of our research was to study the influence of microbial drugs on the base of associative ACC-utilizing bacteria on the soya PMS efficiency in the Orel region conditions.
MATERIALS AND RESEARCH METHODS
Laboratory test were done in the Common Use Center (CUC) «Ecological and agrochemical monitoring of agricultural production and environment» of Orel State Agrarian University, and field tests were carried out in Scientific Educational Production Center «Integration» in 2012-2013.
Plants were grown in crop rotation on plots with area of10 m2 in fourfold replication. The method of experimental plots distribution is randomized.
The experimental plot soil is grey forest and slightly acid (pH - 5,4) with average humus content (4,63%), labile phosphorus (12,7 mg/100g of soil) and exchange potassium (8,9 mg/100g of soil).
The research object is two early-ripening soya varieties: Svapa (selection of All-Russian Research Institute of Legumes and Groat Crops) and Bara (selection of LLC Company «Soya Complex», Krasnodar).
Microbial drugs used in tests are strains of associative bacteria having ACC deaminase activity Pseudomonas oryzihabitans EP4 and Variovorax paradoxus 3P-4, produced in All-Russia Research Institute of Agricultural Microbiology (St. Petersburg). ACC-utilizing bacteria in liquid form were introduced in rows in the sprouting phase (10% sol.). In the test we used general background of fertilizers - 70% the NPK doze, calculated for planned yield capacity, in the form of fertilizer mixture with percentage content of mineral elements 10:26:26.
The tests were carried out according to the following scheme:
1. Control (background - NPK 70%);
2. Background + Pseudomonas oryzihabitans, st. EP4 (introduction in the sprouting phase);
3. Background + Variovorax paradoxus, st. 3P-4 (introduction in the sprouting phase).
RESULTS AND DISCISSION
The results of our researches demonstrated response of the investigated soya varieties to usage of strains of ACC-utilizing bacteria that produced positive biological effect on the plants. It was mainly observed in activation of their interaction with aboriginal strains of nodule bacteria. At this the reaction of the varieties to the biological agricultural methods was not similar (Fig. 1).
Figure 1 - Nitrogenase activity of soya depending on application of microbial drugs, nM C2H4/sol./hour
(flowering phase), average 2012 - 2013
According to the two years experimental data of Svapa variety the strains of associative bacteria being introduced into rhizosphere provided together with the increase of root nodulation ability the sufficient increase of nitrogenase complex activity, which exceeded the control value in 1,5...2,9 times. At this maximum positive effect was provided by bacteria Pseudomonas.
Symbiotic system of Bara variety was less responsive to change of plant nutrition conditions but in general it was characterized with higher functional activity in comparison with Svapa variety. Thus, nitrogen-fixing activity of plants of the given variety increased only in the variant of introduction into soil bacteria Pseudomonas. It exceeded the control level in 1,3 times. Probably, this variety reaction is connected with intensity and composition of plant root exudates that mainly determine life activity and symbiotic activity of soil microorganisms [7].
Functioning of symbiotic system is closely connected with plant photosynthetic activity, which is an energy source for nodule bacteria [8], and which is proved by the obtained results.
Intensification of the symbiotic activity of soya agrocenoses by means of regulation of plant-microbial interactions (PMI) provided increase of both linear and functional parameters of photosynthetic apparatus. At the same time soya varieties reaction to the changes of nutrition conditions was different (Table 1).
Table 1 - Main indicators of soya photosynthetic activity depending on conditions of plants nutrition
(flowering phase), average 2012-2013
Variants Leaf area, sm2/plant Quantum yield (Yield), units.
Svapa
1. Control (background) 454,26 0,648
2. Background + Ps.oryzihabitans 585,22 0,702
3. Background + V. paradoxus 570,67 0,668
Bara
1. Control 612,98 0,652
2. Background + Ps.oryzihabitans 944,15 0,672
3. Background + V. paradoxus 703,44 0,674
Thus, for example, maximum leaf area surface exceeding the control level by 54%, was formed by Bara variety as a reaction to the introduction of strain of pseudomonades Pseudomonas oryzihabitans EP4 into the soil. It was connected with activation of plant symbiotic activity. Thereto, the efficiency increase of primary processes of photosynthesis was detected in the given variant. It is connected with the fact that nodules being powerful attractive centers need in great number of plastic substances to provide their energy demands [8, 9].
At the same time the usage of strain Variovorax paradoxus 3P-4 also allowed considerable increase of biometrical and functional parameters of assimilating surface of leaves of the given variety in comparison with control which was provided by growth stimulating effect of introduced microorganisms on plants.
In the mean time the formation of strong and active symbiotic apparatus of Svapa variety under the influence of bacteria Pseudomonas initiated considerable increase of leaves functional activity at quantum yield increase by 8,3% in comparison with control. At this the leaf area of plants in the given variant was also maximal.
However application of biopreparations on the base of ACC-utilizing bacteria as the main agrotechnology element of the investigated varieties produced positive effect on their seed productivity (Fig. 2).
The varieties under investigation were responsive to all biologization methods, at the same time maximum economic effect was provided by bacteria Pseudomonas.
Thus, yield capacity increment of varieties Svapa and Bara as the result of using pseudomonades on the average for two years was 6,3 and 2,4 dt/ha, correspondingly exceeding the control level by 26,6 and10,1%.
■ Svapa ■ Bara
t/ha
3
2.5 2
1.5 1
0,5 0
Control Pseudomonas Variovorax
Figure 2 - Soya yield capacity depending on regulation of PMI, t/ha (average 2012 - 2013)
In our opinion this positive economic effect is provided by improvement of metabolic important functions of plants at forming associations with ACC-utilizing bacteria Pseudomonas oryzihabitans, st. EP4.
CONCLUSION
Thus, introduction of ACC-utilizing bacteria into agrocenoses of modern soya varieties of north ecotype in the Orel region conditions allowed efficiency increase of their symbiotic systems on the base of nodule bacteria and maximum realization of productivity potential at the account of symbiotically fixed nitrogen. In this case, the efficiency of the introduced strains of microsymbionts mainly depended on the variety.
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