Structure of Micromycete Complex in Agrocenosis of Field Crops on Leached Chernozem of Western Ciscaucasia
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V. S. Gorkovenko et al /J. Pharm. Sci. & Res. Vol. 10(7), 2018, 1834-1839 Structure of Micromycete Complex in Agrocenosis of Field Crops on Leached Chernozem of Western Ciscaucasia V. S. Gorkovenko, I. I. Bondarenko, L. V. Tsatsenko, A. V. Zagorulko, Y. P. Fedulov Kuban State Agrarian University, Russia, 350044, Krasnodar, Kalinina street, 13 Abstract: Monitoring of soils demonstrates that the state of agricultural lands reached the limit beyond which irreversible degradation could occur. The reasons for degradation are a systematic violation of agricultural methods and removal of a high amount of organic and mineral substances with harvest without their adequate recycling into the soil. Soils lose more than 40% of humus, the agricultural harvest is formed due to depletion of soils. At present in Krasnodar krai about 210 thousand hectares of arable lands should be conserved due to exhaustion and degradation. This article presents data on long-term monitoring of mycological state of plants and rhizosphere of each culture of typical grain, grass and hoed crop rotation per one cycle growing, herewith, species composition, trophic and phylogenetic specialization, abundance, spatial and time frequency of occurrence, toxicity of micromycetes have been considered as an integrated index of phytopathologic state of a given agrocenosis. Keywords: phytosanitary situation, phytocenosis, phytopathological microorganisms, micromycetes, humus, monitoring. INTRODUCTION spatial and time-frequency of occurrence, toxicity of According to the data of the state land registry, the micromycetes were considered as an integrated index of capacity of agricultural and arable lands in Krasnodar krai is the phytopathological state of this agrocenosis. highest in Russia. However, incomplete studies in the scope of the land monitoring program demonstrate that the state of agricultural MATERIALS AND METHODS lands reached the limit beyond which irreversible degradation The studies were performed in 1992-2016 on the basis could occur. The reasons for degradation are a systematic of long-term multifactor stationary experiment, Kuban SAU. The violation of agricultural methods and removal of a high amount of experiment is included into the Registry of certificates of long- organic and mineral substances with harvest without their term experiments with fertilizers and other agrochemical adequate recycling into the soil. Soils lose more than 40% of substances of Russian Federation (2002). 11-field grain, grass, humus, the agricultural harvest is formed due to depletion of soils. and hoed crop rotation was established in 1992, located at three At present in Krasnodar krai about 210 thousand hectares of fields with the addition of a new crop every year according to the arable lands should be conserved due to exhaustion and crop rotation layout. The first rotation (1992-2002) included degradation (www.priroda.ru/regions/earth/). alternation of winter wheat with hoed crops and was terminated Degraded soils lost their native microflora, their peculiar with the three-year cultivation of medick, the second rotation structure and functions, they lost the self-cleaning ability. (2001-2011) was started with the following alternation: winter Violation of microbiological processes led to a decrease in anti- wheat, winter barley, and then – winter wheat with hoed crops and phytopathogenic potential, soils started to accumulate actively three-year medick. The third rotation was started in 2010 also toxicogenic microorganisms, mainly phytopathogenic ones. After with alternation of grain and hoed crops. The studies were being accumulated in economically valuable crop seeds, performed in variants with natural fertility status without mineral pathogens stared to prevail and periodically cause epiphytotics. At fertilizers and crop protection agents. Recommended soil present activity of Fusarium fungi in Krasnodar krai has cultivation system was applied: moldboard plowing for hoed increased, they provoke tracheomycosis, root rot, the affection of crops and medick, depth 30-32 cm, and boardless plowing, depth generative organs and leaf apparatus of grain and hoed crops at all 8-12 cm, for winter cereals. Relief of the experimental field was vegetation stages. Micromycete Microdochium nivale is a major smooth. The soils were presented by chernozem, leached, super challenge, in winter wheat it excites snow mold, root and near- deep, slightly humic, slightly clayey, humus content was 2.7- root rot, fusarial leaf burn and Fusarium head blight. Injuriousness 2.9%. Total surface area of the experimental field was 105 m2, of leaf mycosis increased: Septoria blight, a tan spot of winter registration plot for hoed crops and medick was 47.6 m2, for wheat, rhynchosporium, net and stripe notch of winter barley, cereals - 34.0 m2. Triple experiment replication, variant phomopsis and Embellisia blotch of sunflower, the charcoal rot of placement: random blocks. Phytosanitary state of crops was hoed crops. Previously economically insignificant fungi were estimated by conventional phytopathological procedures, spread and became harmful, for instance, Gibellina excitant of micromycetes were extracted from plants and soil using starvation winter wheat - Gibellina cerealis, injuriousness of Alternaria alcohol agar, soil agar, potato sucrose agar, and Czapek's medium. species increased [1, 2]. Fusarium genus was identified according to W. Gerlach et H. The strategy of plant cultivation in Krasnodar krai is Nirenberg, [5], with consideration of current modifications [6- aimed at an increased yield of agricultural crops, one approach to 10]; Bipolaris, Drechslera, Exserohilum, Curvularia geni - the solution of this issue is control of the phytosanitary situation according to B.A. Khasanov [11], with consideration of of agrocenosis. The applied protective measures are based on modification in their taxonomy [12], Alternaria Stemphylium and studies of injuriousness and bioecological properties of individual Ulocladium - according to E.G. Simmons [13-20] and [21]. The types of harmful organisms and improved protection against their other types were identified according to Russian and foreign development [3, 4]. We considered this problem in another way: manuals of identification [22-39]. Quantitative and qualitative we performed long-term monitoring of mycological state of characterization of micromycete complex of the rhizospheric area growing and rhizosphere of each crop of typical grain, grass, of plants was based on procedures of soil mycology [40-44]. and hoed crop rotation per one cycle, herewith, species composition, trophic and phylogenetic specialization, abundance, 1834 V. S. Gorkovenko et al /J. Pharm. Sci. & Res. Vol. 10(7), 2018, 1834-1839 RESULTS In this regard, we tried to differentiate the set of isolated As a consequence of long-term monitoring, 125 types of fungi in terms of food confinement and highlighted three micromycetes were isolated and identified in roots, root crops, relatively conventional groups: pathogenic. saprotrophic, and leaves, stems, and generative organs of plants, including: 71 in mixed. The first group was comprised of micromycetes causing a winter wheat, 57 in winter barley, 47 in sugar beet, 50 in grain pathologic process in all crops of rotation. The saprotrophic group maize, 44 in sunflower, and 50 in medick. The table with species was comprised of typical native types of fungi participating in the composition of pathogenic micromycetes presents the titles of transformation of organic residues and forming soil suppressive holomorphs with regard to the most injurious sporulation stage, properties. The mixed group was comprised of species which, due anamorpha as a rule, with an indication of teleomorph, if any to biological peculiarities, were pathogens in agrocenosis of one (Table 1). crop and saprotrophs in agrocenosis of another group. Taxonomic status of the isolated micromycetes was In rhizosphere of winter cereals, hoed crops and medick, presented by two kingdoms: fungus-like organisms (Chromista) a set of fungi was formed with high species variety: it was and true fungi (Fungi), four Phylums: Oomycota, Zygomycota, presented by 74 species, among which more than one half (58.1%) Ascomycota, Basidiomycota, and Anamorpha fungi group. All were toxigenic. existing types of parasitic specialization were present: from bio- The core of the pathogenic complex was comprised of to hemi- and necrotrophs. dominating or frequently occurring species: Fusarium (F. The group with mono- and olygophag phylogenetic culmorum* (* - hereinafter toxigenic species were shown), F. specialization was comprised of bio- and hemibiotrophs: excitants graminearum*, F. poae*), Alternaria (A. alternata*, A. of false and true mildew, pitch strikes, certain types of spot tenuissima*), Cladosporium (C. herbarum*), Cephalosporium (C. diseases. Depending on biological capabilities during the off- acremonium), Verticillium (V nigrescens, V. kubanicum), season, fungi of this group remained in/on seeds, after-harvest Microdochium nivale*. Time and particularly spatial frequency of residues in the form of teleomorphs, teliospores, mycelium in occurrence of Fusarium (F. solani*, F. oxysporum*, F. leaves of winter crops, in live tissues of intermediate crops and verticillioides*), Pythium (P. ultimum), Verticillium (V. dahliae, medick of the second and third years. In pathogenic complex V. lateritium*, V. tr1icorpus) varied, hence, their quantitative mono- and olygophages were in minority, their fraction