POTATO PHYTONEMATODES GROWN IN DIFFERENT SOILS OF SAMARKAND REGION

ABSTRACT

The article provides information on the fauna and ecology of potato phytonematodes grown in different soils of the Samarkand region. Studies have identified 46 species of phytonematodes. According to the ecological groups of phytonematodes, pararisobionts - 6 species, eusaprobionts - 3 species, devisaprobionts - 15 species, non – disease - causing phytogelmints-13 species, true parasites-9 species. 43 species of phytonematodes have been reported with mechanical composition on light loamy soils, 29 species on medium loamy soils, 27 species on heavy loamy soils, 21 species have been found on all types of soils.

АННОТАЦИЯ

В статье приведены сведения о фауне и экологии фитонематодов картофеля, выращиваемых на различных почвах Самаркандской области. Исследования выявили 46 видов фитонематод. По экологическим группам фитонематоды, параризобионты - 6 видов, эусапробионты - 3 вида, девисапробионты - 15 видов, неболезнетворные фитогельминты - 13 видов, настоящие паразиты - 9 видов. На легкосуглинистых почвах зарегистрировано 43 вида фитонематодов механического состава, на среднесуглинистых - 29 видов, на тяжелосуглинистых - 27 видов, на всех типах почв - 21 вид.

Keywords: phytonematodes, fauna, potato (Solanum tuberosum L.), soil, distribution, parasitic species, ecological groups, dominants.

Ключевые слова: фитонематоды, фауна, картофель (Solanum tuberosum L.), почва, распространение, паразитические виды, экологические группы, доминанты.

Introduction

Global climate changes, soil degradation, the negative impact of anthropogenic factors on nature, especially the increase in the types of pests and parasites in agricultural crops, and the increasing impact on productivity are worrying the world community. One of the parasites of plants are phytonematodes. As a result of the effects of plant parasitic nematodes, the productivity of cultivated plants is significantly reduced in the agricultural sector. Annual damage caused by plant parasitic nematodes to the world economy is 77 billion it is determined to be dollars [1].  Accordingly, it is of great scientific and practical importance to determine the faunal complex of phytonematodes that cause a decrease in productivity, to analyze the population density of phytonematodes in plants and soil, and to develop measures to combat them based on the study of the bioecological characteristics of phytoparasite dominant species.

Along with wheat, corn and rice crops, potatoes occupy the main place in the production of plant products in the world. Potato (Solanum tuberosum L.) is a perennial herbaceous plant belonging to the Solanaceae familyTherefore, it is important to analyze the fauna and ecology of phytonematodes found in potatoes and the soil around the roots of the potato and vegetable growing areas of the republic, including the Samarkand region, and to identify parasitic species.

Analysis of literature on the topic. Information about phytonematodes of potato crops in Uzbekistan, parasite types and their damage, species composition, measures to combat parasites A.T. Tolaganov [11], S.M. Rizaeva [7], D.T. It is presented in the work of Sidikov [10]. However, in Uzbekistan, in particular, in the conditions of Samarkand region, there have been no extensive studies on the population, ecology and taxonomy of the phytonematode fauna encountered in the potato crop. The above-mentioned works focused on the study of one or several types of potato parasites, as well as the available information on the study of potato phytonematodes cannot explain in detail the current situation of phytonematode species encountered in potato crops. At the same time, the species composition, quantity and their development of phytonematodes largely depend on the mechanical composition of the soil, temperature, water-air regime, provision of organic matter, relief structure, plant type, as well as agrotechnical measures, including the use of mineral fertilizers, plowing directly depends on the depth of the layer and others [3, 4, 8, 9].

The purpose of the study. Determining the fauna and parasitic species of potato phytonematodes grown on light, medium and heavy loamy soils in Samarkand region, as well as revealing the ecological characteristics of phytonematodes.

Research material and methods

Research materials were collected from farms and private estates of Taylak, Bulungur, Jomboy districts of Samarkand region. Samples were taken from root and peri-root soils of potato (Solanum tuberosum L.) cultivars "Arizona" and "Sante" by route method [2]. A total of 150 soil and plant samples were collected during the study (50 from each district: 25 roots, 25 soil). Nematodes were isolated from soil and plant samples by the Berman funnel method [2] and fixed in TAF (triethanolamine: formalin: water 2 ratio). A.A. Paramonov [5], E.S. Kiryanova and E.L. Permanent and temporary micropreparations of phytonematodes were prepared according to the methods of Krall. General characters were used to identify nematodes. Species were identified based on external structure [2].

Research results and analysis

During the phytohelminthological studies conducted in potato agrocenoses grown in conditions of light, medium and heavy loam soils of Samarkand region, 46 species of phytonematodes belonging to two subclasses, 5 genera, 17 families, and 25 genera were identified.

The phytonematodes recorded in the soil of potato plant roots and roots were divided into the following groups depending on the degree of occurrence: dominants - 3 species, subdominant - 6 species, recessants - 12 species, subresidents - 25 species, eudominant species were not recorded. The phytonematodes identified in our research were divided into five ecological groups: pararhizobionts - 6 species (13.0 of all species found), eusaprobionts – 3 species (6.5%), devisaprobionts - 15 species (32.6%), non-pathogenic phytohelminths - 13 species (28.4%), true parasites - 9 species (19.5%). According to the ratio of qualitative and quantitative indicators, the number of species of devisaprobionts and phytohelminths that do not cause a specific disease is different, phytohelminths and pararhizobionts that cause a specific disease are relatively less, and eusaprobionts are found in a small number.

During the researches, it was observed that the composition of phytonematodes fauna of potato and its soil around the root in light, medium and heavy sand soils differs from each other according to the mechanical composition. According to the mechanical composition, light sandy loam soils are distributed in the potato field in Taylaк  district. In this region, 329 phytonematodes belonging to 43 species were detected in potatoes. Identified phytonematodes by genera include Plectida 1 species (2.3%), Dorylaimida - 6 species (14.0%), Rhabditida - 14 species (32.5%), Aphelenchida - 9 species (21.0%), Tylenchida - It was 13 species (30.2%).

Pararhizobionts - 6 species, eusaprobionts - 3 species, devisaprobionts - 12 species, non-pathogenic phytohelminths - 14 species, and 8 species of true parasites were observed according to ecological groups (table-1).

Table 1.

Distribution of phytonematodes in different soils with mechanical composition according to ecological groups

According to the mechanical composition of the soil spread in the potato field of Bulungur district, it consists of medium clay soil. 29 species of 151 phytonematodes were detected in potatoes in this region. Identified phytonematodes by genera include Plectida 1 species (3.4%), Dorylaimida - 2 species (7.0%), Rhabditida - 13 species (44.8%), Aphelenchida - 4 species (13.7%), Tylenchida - It was 9 types (31.0%).

Pararhizobionts - 2 species, eusaprobionts - 2 species, devisaprobionts - 12 species, non-pathogenic phytohelminths - 6 species, and true parasites - 7 species were recorded according to ecological groups.

When the ecological groups of nematodes were analyzed by soil types, the species diversity of devisaprobionts and non-pathogenic phytohelminths was relatively high in all soils, moderate in pararhizobionts and true parasites, and low in eusaprobionts.

Therefore, according to the comparative analysis of the phytonematode fauna of potato agrocenoses in light, heavy and medium loamy soils according to the mechanical composition, the highest species diversity was recorded in the soil around the roots and roots of potatoes in light loamy soils - 43 species. In the second place, 29 types of phytonematodes were found in the agrocenosis of potatoes on medium sandy soil, and 27 species of phytonematodes were found in potatoes on heavy sandy soil. According to the distribution of nematodes in the soil around the plant root and around the root, their abundance was observed in the soil around the root compared to the root.

Conclusions

46 types of phytonematodes were identified in potato roots and root peri-soils grown in light, medium and heavy hummock soils in Samarkand region. Identified phytonematodes included one species from Plectida, 6 species from Dorylaimida, 17 species from Rhabditida, 9 species from Aphelenchidae, and 13 species from Tylenchidae.

In the studied areas, the dominant nematodes in the soil around the potato root and root were 3 species, subdominant - 6 species, recessives - 12 species, subresidents - 25 species, eudominant species were not recorded.

According to the ecological classification, phytonematodes recorded in the soil around potato roots and roots: pararhizobionts - 6 species, eusaprobionts - 3 species, devisaprobionts - 15 species, phytohelminths that do not cause special diseases (potential parasites) - 13 species, phytohelminths that cause special diseases (true parasites) ) – made up 9 rounds.

The mechanical composition of 43 types of phytonematodes found in potato agrocenosis was recorded in light sandy soils, 29 species in medium sandy soils, and 27 species in heavy sandy soils. It was also found that 21 species of phytonematodes are common to all soils.

Helicotylenchus multicinctus, Bitylenchus dubius, Pratylenchus pratensis and Ditylenchus dipsaci from the economically important phytoparasitic nematodes of potato plant were found in agrocenoses.

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