Vol 16, No 4 (2021)

The results of two-year experimental data on the growth, development and productivity of spring durum wheat cultivars - Bezenchukskaya Niva and Bezenchukskaya Zolotistaya - in the Chuvash Republic were considered. It was found that decrease in the seeding rate of germinating seeds (from 7 to 3 million per 1 ha) resulted in reducing of the growing period in the studied cultivars of spring durum wheat by 6-7 days. Seeding rate of 5 million seeds per 1 ha provided the maximum density of spike-bearing stems due to the best indicators of general and productive tillering. The formation of the largest main spike with a high grain content in Bezenchukskaya Niva cultivar was noted at the seeding rate from 3 to 5 million seeds per 1 ha. Increase in the seeding rate (> 5 million seeds) led to a decrease in the parameters of the main spike. Analysis of Bezenchukskaya Zolotistaya yield structure did not reveal clear patterns in the change in length and grain size of the main spike resulted from the seeding rate. However, the highest 1000-seed weight (50.4 g) was obtained in the variant with a seeding rate of 6 million seeds pieces. Compared to the control, the maximum yield increase in cv. Bezenchukskaya Niva (1.2 t/ha) was obtained in the variant with a seeding rate of 5 million seeds per 1 ha. The highest yield of cv. Bezenchukskaya Zolotistaya (3.23 t/ha) was obtained at a seeding rate of 6 million seeds per 1 ha.

The goal of the study was to determine the infl nce of forecrops on spring durum wheat productivity and content of soil potassium in monoculture, double-cropping and six-year crop rotation at two types of nutrient statuses. The information obtained as a result of long-term experiments is of great interest, since systematic determination of nutrient elements in soil gives a correct assessment of the effect of the longterm use of fertilizers on soil fertility. Content of available forms of potassium in soil under spring durum wheat depending on different forecrops and nutrient statuses was studied. The best forecrops for durum wheat in 31-year experiments were black, soil-protecting and green fallows. The yield of durum wheat after black fallow was 1.20 t/ha under fertilization and 1.27 t/ha without using fertilizers. Vegetative mass of cropped fallow ploughed into soil and use of mineral fertilizers led to an increase in content of soil potassium. The use of mineral fertilizers has a positive effect on yield of durum wheat; the yield increase was 0.10 t/ha after soil protecting fallow, 0.11 t/ha after common wheat and 0.13 t/ha after winter rye. Content of soil potassium was higher in six-year crop rotation and it increased durum wheat productivity compared to double-cropping and monoculture.

Rice is one of the most widespread and cultivated crops in the world. It is necessary to increase the yield of crops or expand their sown areas to resolve a food security problem in Russia. Current impossibility of expanding rice cultivated areas in the Rostov region and the need to maintain and increase its yield require developing new disease-resistant varieties. Rice genotypes with multiple blast resistance genes avoid significant yield losses. Since pyramiding and selection of resistance genes in the same genotype through traditional selection methods are complicated, it is urgent to search for homozygous samples using marker-assisted selection methods. This study was aimed to identify Pi-1, Pi-2, Pi-33 and Pi-ta blast resistance genes in breeding rice samples by MAS-methods. The study used CTAB-method for DNA-isolation, PCR, electrophoresis on agarose and polyacrylamide gels. The resulting gels were stained in a solution of ethidium bromide and photographed in ultraviolet light. To control the presence of blast resistance genes the following parental cultivars were used: C104LAC for the Pi-1 and Pi-33 genes, C101-A-51 for the Pi-2 gene, IR36 for the Pi-ta gene; Novator and Boyarin as controls of non-functional alleles of all studied genes. The 446 selection samples of the seventh generation were analyzed. As a result of the research, 127 rice samples that combine 2 or 3 different blast resistance genes were identified. The Pi-2 and Pi-33 genes combination was identified in 43 samples (1128/1, 1149/3, 1171/2, 1177/3, 1177/4, 1186/4, et al.). Samples with three resistance genes are the most interesting for selection and further breeding. For developing new blast-resistant varieties, we recommend using rice samples with the following combinations of resistance genes Pi-1+Pi-2+Pi-33 (1197/1, 1226/2, 1271/1, 1272/2), Pi-1+Pi-2+Pi-ta (1197/4, 1304/2, 1304/3, 1482/3, 1482/4, 1486/1) and Pi-2+Pi-33+Pi-ta (1064/1, 1064/3, 1281/2, 1281/3, 1281/4, 1282/2, 1283/1, 1283/2, 1284/3).

Rust is one of the most economically important foliar diseases of sunflower. The problem of sunflower disease control was considered. The article presents the results of a two-year experiment studying the efficiency of AMISTAR® Gold fungicide, concentrated suspension (active ingredient: Azoxystrobin 125 g/L, Difenoconazole 125 g/L) in sunflower hybrids in the Lower Volga region. Flowerbud development stage was the best application timing for increasing productivity. Therefore, sunflower yield averaged 3…4 c/ha. The biological efficiency of the fungicide ranged from 85 to 90 %. The calculation of economic efficiency showed 145…255 % profitability depending on the year.

The full exploitation of the resource potential of arable lands was analyzed in the research. The problem of completeness of the use in different farming systems was considered. It was found that at the current stage of development of farming systems, the diversity of soils and lands and, accordingly, their resource potential were most successfully incorporated in adaptive-landscape farming systems and precision farming systems. Undoubtedly, the cost of precision farming systems will decrease in the future due to the cheapening of technical means. But without introducing scientific and methodological justification for accounting of diversity of soils and land plots (as in adaptive-landscape farming systems) and heterogeneity of crops into precision farming systems, increasing the completeness of land resource potential cannot be achieved. Another important direction to improve the full use of the land resource potential is the development of a new scientific direction - Econics, and the development of technologies for leveling the heterogeneity of fields. But these directions are at the very beginning of their development.

Layered silicates, such as serpentine and vermiculite, have properties that make it possible to use materials based on them as components of environmental technologies. The possibility of soil remediation in industrially contaminated area, formed due to the long-term exposure to emissions from copper-nickel production (Monchegorsk, Murmansk region), was studied. Two materials were used as ameliorants in our study: expanded vermiculite and granular serpentine sorbent, a waste after using the purification technology of highly concentrated solutions from metals. These materials have a high sorption activity to several metals, a high specific surface area, the ability to retain moisture, and are available in quantities sufficient to work on the remediation of large areas. A study of the physicochemical properties of industrially polluted soil and ameliorants, direct phytotoxicity testing of podzol and its mixtures with expanded vermiculite and the serpentine sorbent (test plants - common oat Avéna satíva L. and red clover Trifolium praténse L.) were carried out. The study results showed that the proposed materials were effective additives for increasing the pH of acidic soil, sorption and precipitation of Al and potentially toxic metals - Cu, Ni, Pb, Fe, and improving the soil hydrophysical and agrochemical characteristics. A positive response of test plants to the introduction of ameliorants into industrially contaminated soil was noted.

Forest pastures with different tree crown cover were studied. The seasonal dynamics of the yield and nutritional value of grass and twig-leaf fodder of forest pasture was studied. The unsystematic use of pastures in arid territories has increased the process of degradation and has become one of the factors of depletion of their natural vegetation. The use of forest reclamation in the 70s and 90s on sandy lands and pastures in the Western Caspian region made it possible to create significant areas of forest pasture land with strip and massive stands of Ulmus pumila L. and Robinia pseudoacacia L. Different types of tree stands created on pastures not only improve the microclimate and form a comfortable environment for grazing animals, but also are an additional source of valuable twig feed. The aim of the research was to study forage productivity of forest pastures with different types of plantings on the sands of the Western Caspian region. The objects of the research were forest pastures with different species composition and tree crown cover. Studies on the forage productivity of forest-reclaimed pastures were conducted in 2018-2020 on the basis of the North Caucasus branch of Federal Scientific Centre of Agroecology, Complex Melioration and Protective Af-forestation of the Russian Academy of Sciences. The research was based on field experiments and laboratory analyses. According to the results of the study, forest-reclaimed pastures with unsystematic grazing had 1.5…2-fold increase in productivity compared to natural ones. The largest amount of twig-leaf feed was formed in broad-band Robinia stands in summer-autumn period. The total gross stock of natural pastures of the Western Caspian region did not exceed 0.3…0.4 t/ha of dry weight, the consumed stock was 0.2…0.3 t/ha. With the help of strip and massive plantings on degraded pasture lands, it is possible to increase significantly their productivity and quality with the achievement of 7 MJ of exchange energy and 0.26…0.29 feed units in 1 kg of elm and robinia twig-leaf feed during droughts.

Land is one of the key resources in agricultural production. The use of these resources is signifi antly different from the use of labor resources and financing. It is the land features that affect the assessment of their use efficiency. The analysis of literary sources has shown, there are a large number of approaches and methods to assess the effectiveness of land resources. This indicates a great interest of researchers and practitioners in the issue under study. Each of the researchers offers their own unique methodology for assessing the efficiency of land use. However, it is impossible to distinguish a single method due to various reasons. Nevertheless, it should be noted that the proposed methods are complementary. The main goal of this study was to assess the effectiveness of agricultural land use in France. In this regard we used following methods: analysis and synthesis, graphical method, method of comparisons. The analysis was carried out in three stages. The dynamics and structure of agricultural lands of the country, the harvested areas of the main groups of agricultural crops were analyzed, both cost and natural indicators were calculated. As a result, we can say that the studied indicators should be used in the express assessment of efficiency, they can also be used in the comparative assessment of the efficiency of agricultural land use. For a deeper assessment, in our opinion, it is necessary to use other methods of analysis.