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UDC 633.11 "324":632.25:63:551
AN ASSESSMENT OF TYPES OF WINTER WHEAT ACCORDING TO AFFECTION BY ROOT ROT IN SPECIFIC AGROCLIMATIC CONDITIONS AS ELEMENT OF SCIENTIFIC AND REASONABLE STRATEGY OF THEIR USE
Shutko A.P., Associate Professor Stavropol State Agrarian University, Stavropol, Russia E-mail: schutko.an@yandex.ru
ABSTRACT
It is established that in the conditions of three main agro climatic zones of Stavropol region the complex of root rot activators is presented generally by fungi of the sorts Fusarium and Bipolaris, and since 2009 and Gibellina cerealis Pass. The affection by root rot and injuriousness of a disease vary depending on high-quality features of winter wheat and cultivation soil climatic conditions. The amount of produced lignin for each percent of the disease in plants varieties of winter wheat, the degree of development of the disease does not exceed the minimum value of economic threshold of injuriousness, ranges from 29 to 54 mg/g of dry weight, plant varieties, the intensity of the disease for which reaches and exceeds economic threshold, synthesize not more than 27 mg/g.
KEY WORDS
Winter wheat; Varieties; Root rot; Complexes of activators; Number of synthesized lignin; Injuriousness.
Recently the aggravation of a problem of stability of development of agriculture owing to negative consequences of person's economic activity, such as soil structure destruction because of using of heavy cars and mechanisms, a water and wind erosion, soil salination, pollution of reservoirs, accumulation in food of nitrates and residual amounts of pesticides as a result of unreasoned application of mineral fertilizers and chemical means of protection of plants is observed. The high-yielding agro-environmental adapted for conditions and technologies variety (group of varieties) makes up the basis of an intensive grain production. This very variety, its genetic opportunities define potential efficiency of grain crops in this region, in this crop rotation and on this field. The adopted and integrated systems of protection against harmful organisms have to be developed for a variety (for groups of varieties) created by selectors for different agro zones, different crop rotations and different agro technologies. Naturally, different varieties demand different intensity of protective measures which depends on ability to resist to phytopathogens [7, 10].
Stavropol region located in the center of Ciscaucasia (between 43°45'-46°15' northern latitude and 40 °50 '-45 °40' east longitude), traditionally is included into the three of major grain sowing regions of the Russian Federation. Annual crops of winter wheat and winter barley are 1,6 million hectares. The root rot play an important role among the biotic stressful factors having impact on formation of a crop and qualitative characteristics of winter wheat's grain. Root rot reduce productivity to 60%, due to the certain conditions, thus also grain's quality is considerably dropped off. The purpose of work was the comparative phytosanitary assessment of winter wheat’s varieties on affection by root rot in agro climatic zones of Stavropol region.
MATERIALS AND RESEARCH METHODS
Researches were conducted in 2005-2011 by setting up laboratory and field experiments in phytopathology and entomology chair, at experimental station of Federal State Budget Educational Establishment of Higher Professional Training "Stavropol State Agrarian University" (a zone of unstable moistening), and also on collective farm "Rodina" of the Novoselitsk area (droughty) and Agricultural Production Co-operative "Russia" of the
Apanasenkovsk district of the Stavropol region (the extremely droughty agro climatic zone). Route inspections about detection of contamination root rot were carried out on crops of winter wheat in the agricultural enterprises of Stavropol region.
Phytosanitary condition of winter wheat was studied according to A.E. Chumakova and T.I. Zakharova's techniques [8]. Structure of activators root rot was determined by a method of root's fragmentation and the footstalks affected by root rot, by N.I. Kolnobritskomu, V.P. Bondaryu [3]. Identification of fungi was carried out according to N. M. Pidoplichko [5]. Definition of a "crude" lignin carried out by A. I. Ermakova's technique, etc. [2]. Morpho-physiological parameters were determined by State test duration of the varities's technique of crops [4].
RESULTS AND DISCUSSION
The areas of crops grain, including winter wheat as leading culture, are concentrated in three agro climatic zones of Stavropol region: the extremely droughty, droughty and zone of unstable moistening. The moisture regime is the limiting factor defining a complex of disease excitant, a phytosanitary situation, technology of cultivation, including system of protection of plants. As a result of researches it is established that in the conditions of three main agro climatic zones of the Stavropol region the complex of root rot activators is presented generally by fungi of the sorts Fusarium and Bipolaris (tab. 1).
Table 1 - Complexes of root rot activators of winter wheat depending on agro ecological conditions
(the Stavropol region)
genus frequency range %
Leached black soil (zone of unstable moistening) South black soil (droughty zone) light-chestnut soil (extremely droughty zone)
Fusarium 47,5 25,4 11,3
Bipolaris 20,3 30,8 2,0
Ophiobolus 8,0 1,0 0
Cercosporella 3,2 0 0
Pythium 6,7 13,1 0
Alternaria 3,6 2,2 2,0
Pseudomonas 3,4 23,0 0
others 10,3 7,7 18,6
The emergence of ophiobolus cercosporella root rot, dated for more damp ecological conditions in a droughty zone southern black soil is equal to nearly zero. However more humid region in comparison with mean annual indicators humidified ears of researches were led to emergence of disease in such winter wheat varieties as the Starshina, Zernogradka 9 and Prikumskaya 115.
The increase in biological diversity and density of populations of saprotrophic microbe antagonists in soil microbiota defines soil's fungistasis and a affection of cultural plants by root rot. From references it is known that some of genus Penicillium fungi act as producers of toxic antibiotics, decomposing infectious rudiments of a mushroom, up to lysis [1].
Calculation of correlation's coefficient between the frequency of occurrence of fungi of the Penicillium and Bipolaris varieties showed average feedback (coefficient of correlation of r=-0, 475). Depending on high-quality features of winter wheat plants the coefficient of correlation varies from-0,313 to-0,991.
Thus, the researchers showed that on light-chestnut soil only at grades Donskaya jubileinaya and Don 95 varieties fluctuations in settling of root system of plants with Bipolaris fungi are defined on 95,6-98,2% by intensity of development of Penicillium fungi. Stanichnaya variety has the indicator 46,1%; by other options of experience - 9,7-22,0%.
The comparative assessment of winter wheat varieties for the root rot affection in various soil climatic conditions at cultivation on pure steam showed, that poorly affected by root rot on the southern black soil in a droughty zone of Stavropol region of Deya and Batko's varieties (extent of disease's development 3,9 and 9,1% against Economic Threshold of
Harmfulness - ETH=10-15%) on the leached black soil in a zone of unstable moistening show higher susceptibility (in 6,0 and 2,1 times, respectively) to diseases excitant (tab. 2).
One of mechanisms of stability to phytopathogens is modification of plants' cell walls by a way of lignin deposition and accumulation. Researchers showed that the maintenance of a lignin in plants' fabrics of winter wheat considerably varies depending on high-quality features. The quantity of the formed lignin for each percent of development of plants' disease at the winter wheat which variety are least affected by root rot (extent of development of an disease on which doesn't exceed the minimum value of an economic threshold of harmfulness of ETH=10-15%), fluctuates from 29 to 54 mg/g of the dry weight (tab. 3). Such varieties of winter wheat as Stanitsa, the Rostovchanka 3, Ermak intensity of a disease on which reaches and exceeds ETH, synthesize no more than 27 mg/g of dry weight of a lignin for each percent of development of an disease isn't enough for effective localization of a pathogenic mycelium.
Table 2 - The affection of winter wheat by root depending on high-quality features and soil climatic
conditions, a phase of dairy and wax ripeness
variety droughty zone zone of unstable moistening
abundance;%; extent of disease's development, % abundance% extent of disease's development %
Starshina 90,6 19,7 100,0 26,9
Pricumskaya 115 94,0 23,1 96,6 14,6
Deya 78,7 3,9 96,4 23,8
Batko 95,1 9,1 96,3 19,9
Ryfa 91,4 14,6 87,1 15,6
Zernogradka9 98,3 18,8 91,2 18,9
Vicrory50 83,9 22,2 82,8 22,9
Pricumskaya 140 97,7 23,1 100,0 35,9
Pricumskaya 141 100,0 24,2 100,0 19,5
Donskaya unbearded 98,0 30,2 96,6 16,8
Table 3 - The maintenance of a lignin in fabrics of winter wheat's plants depending on high-quality
features
Variety Extent of development % Contains of a lignin, mg/g of dry weight
at the actual level of development of a disease for 1 % of extent of development of a disease
The variety of erythrospermum
Starshina 4,3 230,91 53,70
Ukrainka odesskaya 5,1 225,78 44,27
Donskaya Jubileinaya 11,0 263,11 23,92
Stanichnay a 13,8 222,48 16,12
Rostovcha nka 3 14,6 248,27 17,00
Ermak 18,3 299,17 16,35
The variety of lutescens
Don 95 7,4 261,23 35,30
Tanya 7,8 236,50 30,32
Deya 8,7 252,51 29,02
Batko 10,7 290,24 27,13
HCP05 6,6
Sx% 2,2
It is known that at rather low level of defeat by phytopathogens at plants intensity of breath increases, exchange reactions of physiological processes amplify that finally promotes some increase of efficiency of population as a whole. The comparative analysis of
structure of a crop of healthy and sick plants of studied varieties in the conditions of a droughty agro climatic zone showed that the most evident immune reaction of plants of winter wheat to a prevalence root rot is observed at the variety Don unbearded (tab. 4).
Table 4 - Structure of a crop of sick and healthy plants of winter wheat of various varieties
Variety Affection point by root rot Amount of grains in an ear, piece The mass of grain in an ear, Weight of 1000 grains,gr Productivity, c/hectare Average productivity, c/hectare (according to varieties' authors )
Deya 0 34,4 1,23 35,750 56,6 47,4
0,1 31,9 1,06 33,320
1 31,0 1,19 38,390
2 - - -
Batko 0 46,5 1,50 32,690 54,9 60,2
0,1 45,9 1,64 35,590
1 42,3 1,48 35,030
2 14,8 0,47 31,790
Don unbearded 0 32,1 1,13 35,050 50,6 57,6
0,1 33,9 1,18 34,903
1 38,5 1,35 35,190
2 34,8 0,63 31,600
Calculation of coefficients of injuriousness root rot, expressing the losses of efficiency falling on unit of defeat (point), and the corresponding possible losses of a crop in specific ecological conditions for studied grades showed, that possible grain losses because of incidence root rot on the south black soil in droughty zone of the Stavropol region, Deya, Batko's varieties and can Don unbearded make at most 8,0, 1,6 and 4,3% or, proceeding from average productivity according to authors' variety o - 3,8, 0,9 and 2,5 c/hectare.
In 2009 in the territory of the Stavropol region the affection of winter wheat crops by white straw disease, or gibellina stalks rot (Gibellina cerealis Pass) was revealed. According to branch of Federal State Institution "Russian agricultural centre" in the Stavropol region the disease was noted on the area of 113,0 thousand hectares (9% from the surveyed area) in 22 areas. In 2011 the disease was registered on the area of 1048,0 thousand hectares (62% from the surveyed area) in all 26 regions [6].
Diagnostics of this rot is complicated as symptoms of affection are very similar to affection by fungi of the genus Cercosporella and Rhizoctonia. Researches of peculiar features of display of gibellina stalks rot were conducted in the conditions of a droughty agro climatic zone of the Stavropol region. White straw disease or gibellina stalks rot is shown in the form of eye spottiness with accurately designated border of coffee color on a stalk, the tillering generally are higher than a knot.
Spots' length are 3-5 mm. At thorough plant investigations fundamental differences of gibellina affection from affection by such pathogens, as Cercosporella and Rhizoctonia affection are visible, especially - in the center of spots in case of white straw disease affection always there is a pruinosity of dark gray color (fungi stroma), on appearance reminding charcoal or cigarette ashes which is well visible with the naked eye. Gibellina affection becomes well noticeable in the tillering phase. From one to three eyes can be located on one stalk.
While plants are growing a spot extend up on a stalk. In case of strong development of a pathogen they can cover completely a stalk and even to merge among themselves. The plentiful mycelium pruinosity is formed on the spots: at first white (from here the disease name), then in process of aging - gray color (fig. 1).
Small black sklerotion on which the peritetion acting by the beginning of a phase of earing as air pores through vaginas of leaves over time are formed on a mycelium. As a result the lower part of a stalk of the struck plant takes a "bristly” form. So, it is shown as radical rot, and then - rot of stalks, before booting phase of gibellina.
Figure 1 - Gibellina cerealis mycelium (according to A. P. Shutko, etc., 2012)
The researches’ results showed that in the conditions of a droughty agro climatic zone of the Stavropol region Petrovchanka variety appeared the variety of winter wheat most struck by gibellina rot. Studied varieties of winter wheat successfully resisted to Gibellina cereals Pass activator distribution from sick plants to healthy that was shown in decrease in prevalence of a disease by the end of the vegetation period. Jubileinaya 100 variety is an exception.
White straw wheat disease is very harmful. There is dyewood of plants because of dying off of plants as a result of strong affection or in a case in a stage of a shilets, and dying off of the struck escapes in a phase of a tillering reduces tillering coefficient to an exit phase booting. As a rule all shoots of one plant are affected because of the long period of infection. Stalks either don't come into ear or the formed ears badly. Strong defeat in late terms of a booting phase results in fragility of a stalk, and in case of defeat of a flag leaf and wheat’s ear doesn't blossom, and weevils aren't formed. Gibellina breaks carrying-out system of a plant that worsens conditions of supply of all bodies’ water and nutrients. It leads to a partial or full white spike.
Table 5 - Elements of structure of winter wheat's crop depending on high-quality features and extent
of defeat by gibellina stem rot
Variety (elite) Point affections Amount of grains in one ear, piece Grain mass in an ear Mass of 1000 grains
Moskvich 0 38,3 1,65 42,952
1 spot 49,7 2,2 44,422
Jubileinaya 100 0 27,9 1,11 39,627
1 spot 25 0,98 39,200
Pamat' 0 38,3 1,53 39,948
2 spots 14 0,45 32,143
Batko 0 24,5 0,85 34,494
3 and more spots 26 0,59 22,692
Rostovchanka 0 34,7 1,48 42,794
1 spot 25 0,83 33,200
Petrovchanka 0 29,8 1,06 35,479
2 spots 29 0,95 32,758
3 and more spots 16 0,30 18,745
The analysis of injuriousness of gibellina stem rot shows that winter wheat Muskvich observes active immunological reaction in reply to a poor development of an illness (1 spot on a stalk): as a result such indicators, as amount of grains in an ear, the mass of grain from an ear and the mass of 1000 grains (tab. 5) increase. The plants Jubileinaya 100 and the Rostovchanka varieties in reply even on weak affection of activators show deterioration of
indicators of crop structure. More intensive development of an disease (2, 3 and more spots) that led to violation of filling processes which form grain and as a result, reduction of weight of grain from an ear was noted on plants of winter wheat of grades Pamat', Batko and Petrovchanka. Moreover, plants of Pamat' and Petrovchanka varieties at stronger affection form smaller amount of grains in an ear.
CONCLUSION
Orientation of process intensification in plant growing on energy saving and nature protection assumes reduction of application of pesticides on the basis of increase of a role of mechanisms and self-control structures in agro coenosis and agro landscapes. So, the most important problem of the nearest future is development and universal introduction in practice of the scientific principles of zone conducting the agriculture, ecologically less dangerous means of protection of plants.
In ecologic systems of plants' protection the main role belongs to monitoring of development of the harmful organisms which results are a cornerstone of the conceptual scheme of protection of winter wheat from a complex of phytopathogens, including root rot. Data on a variety's affection in specific agro climatic conditions are a basis for justification of structure of high-quality crops.
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