Meadow Brown Soil Research Articles

Loss of nutrients from meadow-brown soils during irrigation of apple trees in the conditions of the dry subtropics of Azerbaijan

The article presents the results of studies on the effect of water consumption, depending on the length (96, 144 and 192) meters of irrigation furrow with a slope of relief tg = 0.021 on the leaching of nitrogen, phosphorus and humus from irrigated soils of the dry subtropics of Azerbaijan under apple trees. Under conditions of leaching of nutrients, the effect of mineral and organic fertilizer systems on apple yields has also been studied. With a 96-meter furrow and a water consumption of 0.2 l/sec, the content of leached nutrients (N, P) and gross humus with soil was 0.01 % nitrogen and phosphorus, 0.02 % gross humus. Increase in water consumption from 0.2 l/sec. up to 0.4 l/sec. It has a negative effect on the leaching of humus, nitrogen and phosphorus from the soil. With a water consumption of 0.4 l/sec, these indicators increased markedly by 0.01 % for humus, nitrogen and phosphorus. Along the length of the irrigation furrow in both water consumption rates, the leaching of nutrients and humus from the soil increases. It was found that with an increase in the length of the furrow to 192 meters at a water consumption of 0.4 l/sec, the leaching was greater than the 96-meter furrow in humus by 0.22 %, nitrogen by 0.07 % and phosphorus by 0.04 %. The use of an organomineral fertilizer system (Background+ N120P120K90) had a positive effect on the yield of apple trees. Thus, in the non-maneuverable version on a 94–meter furrow, the yield of the apple tree was 274.2 c/ha - when the furrow was lengthened to 192 m, the yield gradually decreased due to the high content of leached nutrients and humus (268.5 c/ha). When using N120P120K90 + 10 t/ha of manure, 278.4 c/ha yield was established at 96 m furrow and 0.2 l/sec of water consumption. Whereas, when the furrow was lengthened to 192 m at the same rate of fertilizers and water consumption, the yield decreased to 278.2 c/ha, that is, furrow lengthening was ineffective at slopes tg = 0.021. It was found that at high slopes, the shorter the furrow, the less nutrients are washed out.

Микробиологические показатели лугово-коричневых почв естественных ценозов

The article presents data on microbiological indicators of meadow-brown soils of semi-humid subtropics of the Lenkoran region. Meadow-brown soils are typical representatives of a number of hydromorphic soils of Azerbaijan. These soils are formed under sparse forests and shrub plantations with well-developed herbage. The soil-forming rocks are deluvial-proluvial deposits of clay composition. The influence of groundwater and surface runoff on soil formation is periodic. In the described soils, biological processes, including the activity of microorganisms, take place at moderate moisture level (10–25%) and temperature (18–23 °C). The paper presents a comparative analysis of the total number of microorganisms (in a layer of 0–50 cm) between typical meadow-brown, meadow-brown leached, meadow-gray-brown and gray-earth-meadow soils. We have shown changes in the total amount of microbiota for individual horizons of meadow-brown soils. Changes in the quantitative indicators of the microbiota of the studied soils also affect their overall biogenicity. A close relationship has been established between humus and the number of microorganisms. As the humus decreases in individual horizons, an adequate decrease in the number of microbiota is noted. If in 0–5 cm, 5–10 cm, 10–15 cm layers the amount of microbiota varied between 6,13–5,83–4,81 million per gram of soil, then in deeper layers of 15–20 cm, 20–25 cm, 30–40 cm, 35–50 cm, their number gradually decreases to 3,9–3,10–2,65–1,81–1,52 million per gram of soil.

MİL-ARAN QARABAĞ KADASTR RAYONUNDA TORPAQ EHTİYATLARINDAN İSTİFADƏNİN VƏZİYYƏTİ

Mil-Aran Karabakh cadastral region includes Barda, Agjabadi, Beylagan, Tartar regions as a whole, Aghdam, Aghdara region and Khojavend plain lands. Gray-meadow, meadow-forest, subasar alluvial meadow, gray, meadow-swamp, chestnut, meadow-chestnut soils are spread in the territory of this cadastral region. Grass-gray soils are transitional and are distributed in the strip between the gray-brown (chestnut) and meadow gray-brown (chestnut) soils of the dry steppes and the gray soils growing in drier conditions. Very large areas of the described lands are used for irrigated agriculture. The subasar regime of rivers and the resulting fresh alluvial sediments play a key role in the formation of subasar meadow-forest soils. During the autumn season, especially during floods, the rhythm of soil formation is repeatedly disrupted. This, of course, is reflected in the properties and morphological structure of these soils. Areas with gray soils have an arid semi-desert and dry steppe climate with an average annual temperature of 13.5-14.60. The temperature of the hot months is much higher. Unlike subasar meadow-forest lands of our republic, subasar-meadow soils are formed under meadows and shrubs. Rich grasses play an important role in enriching these soils with organic matter and ash elements. Meadow-swamp lands are spread in a relatively limited area of the republic. These soils are usually formed in the low and lowlands of the relief. The ecological and geographical features of the meadow-brown soils are in many respects similar to those of the brown soils. However, hydrothermal conditions are distinguished by the large seasonal differences, additional moisture due to surface and ground moisture. Our area is subject to varying degrees of salinization and erosion. We know that saline soils are lands with salts that are easily soluble in water in a 2-meter layer of soil. The effect of groundwater on soil salinization also depends on the degree of mineralization of that water. In this case, the crisis rate of groundwater mineralization is taken. Key words: Groundwater, mineralization rate,salt accumulation, irrigated soils, drainage rate

Связь между физико-химическими и биологическими показателями лугово-коричневых почв

The article presents the results of research on the relationship between some physicochemical and biological indicators of meadow-brown soils of semi-humid subtropics of the Lenkoran. The characteristic relationships between the humus content and the absorption capacity, as well as between the number of microorganisms and the reactions (pH) of the soil environment, have been studied. The analysis of the dependence of the investigated quantitative indicators is presented. As a result, it is concluded that there is a relationship between the soil absorption capacity and the humus content in meadow soils. The pH of the soil medium ranges from neutral to slightly alkaline.

Физико-химические свойства лугово-коричневых почв

The research has established that the carbonate content of meadow brown soils in the upper and lower horizons varies between 1–9–11%. Where in, the calcium content reaches 85–90%. The content of physical day and silt fraction is 42–75% and 24–36% respectively and is concentrated mainly in the middle part of the profile.

К изучению гумусного состояния лугово-коричневых почв

Abstract. The studies carried out and the results obtained on the humus state of meadow brown soils are fully consistent with the literature. The change in the humus content in the soils of the meadow soil formation process depends on the effect of surface and ground moisture on humus formation. Studies have revealed that the humus content in meadow brown soils decreases gradually and relatively evenly with depth. For meadow soils with a meadow process of soil formation, there is a general tendency for a decrease in humus from the upper horizons to the lower ones.

Environmental assessment of the use of the herbicide Lumax

The sensitivity of agricultural crops to the Lumax herbicide, consisting of three active agents C-metolachlor, terbutylazine and mesotrione, the duration of their action in meadow-brown soil, and the aftereffect of the herbicide on the plants of the crop rotation were determined. The study was conducted in the conditions of the greenhouse in the Primorsky Territory in 2019 and 2020. The herbicide Lumax was used on experimental plots before corn germination at doses of 4.0 l/ha (recommended) and 8.0 l/ha (twice the recommended). In the autumn of 2019 and in the spring of 2020, samples of meadow-brown soil were taken from the experimental plots and from the control (without herbicides) from the depth of the arable layer containing 3.5% humus. The samples were used to establish the duration of the action of active agents and the aftereffect of the herbicide Lumax. Prior to this, plants indicating residual amounts of the chemical in meadow-brown soil were preselected. The doses of the herbicide which reduce the above-ground mass of the test plant by 50% were calculated, as well as its maximum permissible concentration in the soil. It was determined that by the end of the growing season, 0.7–3.0% of the active agent of the herbicide Lumax is retained in meadow-brown soil at a rate of application of 4.0 l/ha, and 0.6–3.9% – at a rate of 8.0 l/ha. By the beginning of the next field season, the preparation applied at the recommended rate completely decomposed, while when it was applied at a double rate of the recommended rate, 0.8–1.7% of the herbicide remained. Eight months after the application at a rate of 4.0 l/ha, the herbicide Lumax is safe for subsequent crops of the crop rotation. In case of overdose or double application (8.0 l/ ha), it can have an aftereffect on sensitive crops. The crops that are highly sensitive to the Lumax preparation were identified: cabbage, radish, rapeseed, beetroot, tomatoes, cucumber and rice; sensitive: wheat, buckwheat and soybean; relatively resistant: oats and barley. A safe consumption rate of the Lumax herbicide (4.0 l/ha) for subsequent crops of the crop rotation was established.

Растительность и ее значение в формировании лугово-коричневых почв

The studied meadow-brown soils of moderately dry subtropics of Azerbaijan are formed under thinned forest-bush and lacustrine — grass vegetation. In meadow-brown and other types of meadow soils, vegetation development and phytomass formation are influenced by soil and surface moistening. Aboveground phytomass which plays an important role in humus formation of natural and cultural cenoses of meadow soils creates plant biomass of 32–60–76 cwt/ha and 55–110–119 cwt/ha.

Studying the Reclamation State of the Irrigated Meadow Brown Lands in Araksavan Community of Ararat Region

Improvement of land reclamation methods and ecological state of the soils is essential for the sustainable development of agriculture in Armenia. The aim of the current work is to study the chemical composition of the irrigated meadowbrown soils with an area of 25 hectares in the village of Araksavan. The results of the study showed that this land plot is not homogeneous in chemical composition. The studied soils are saline and alkaline, and without any chemical reclamation it is impossible to use them in agriculture. Thus, it is recommended to conduct chemical reclamation activities in the mentioned land area.

Influence of Fertilizer Systems on Soil Organic Carbon Content and Crop Yield: Results of Long-Term Field Experiments at the Geographical Network of Research Stations in Russia

The results of long-term experiments (LTEs) performed at the Geographical Network of experimental stations encompassing major soil types in Russia (soddy-podzolic (Retisols, Luvisols, and Podzols); gray forest (Luvic Greyzemic Phaeozems); leached, typical, and southern chernozems (Chernozems); chestnut soils (Kastanozems); meadow brown soils (Albic Stagnic Luvisols); and meadow chernozem-like soils (Luvic Greyzemic Stagnic Phaeozems)) within the entire country (from the north to the south of the European part of Russia, Siberia, and the south of the Far East region (Amur oblast, Khabarovsk, and Primorskii regions)) are summarized. Most of the stationary LTEs were lasting 20–45 years; ten LTEs lasted from 50 to 81 years. It was found that the organomineral fertilizer system (OMFS) exceeded the mineral fertilizer system (MFS) in its effect on the yield by 1–40% in 18 experiments, while the MFS was more efficient than the OMFS by 2–3% in only three LTEs. For the same soil type, the differences in Corg content between unfertilized trials reach 0.56–1.55% for soddy-podzolic soils and 1.58–3.93% for chernozems. Differences in soil Corg content between the unfertilized and OMFS (manure + NPK) trials were less than 10% in four LTEs, 11–20% in six LTEs, and >20% in ten LTEs; the average difference reached 0.27% of Corg. The levels of minimum (Cmin) and optimum (Copt) organic carbon content have been determined with due account for the soil types, soil texture classes, and the applied fertilizer system. They can be used as reference values for the studied soils.

Урожайность травосмесей из многолетних трав в зависимости от фона минерального питания на лугово-бурой оподзоленной почве в условиях Приморского края

В статье приводятся результаты изучения влияния минеральных удобрений на урожайность бобово-злаковых травосмесей на лугово-бурой оподзоленной почве Приморского края. Исследования проводились в 2012–2015 годах на опытном поле ФГБОУ ВО «Приморская ГСХА». Двухфакторный полевой опыт закладывался по следующей схеме: фактор А — различные по составу травосмеси многолетних трав: 1 — овсяница луговая + клевер луговой; 2 — овсяница луговая + лядвенец рогатый; 3 — овсяница луговая + клевер луговой + лядвенец рогатый; 4 — тимофеевка луговая + клевер луговой + лядвенец рогатый; 5 — кострец безостый + лядвенец рогатый; фактор В — фон удобрений: 1 — без удобрений (контроль); 2 — Р120К90; 3 — Р120К90 + N60. Установлено, что урожайность зелёной массы зависела от состава травосмеси, укоса и нормы внесения удобрений. В различные по климатическим условиям 2012–2015 годы исследований травосмеси отличались по урожайности. Самый высокий урожай во все годы исследований был получен в первом укосе, что связано с особенностями приморского климата и биологией многолетних трав. Наибольшую урожайность в первый год пользования обеспечили более сложные трёхкомпонентные травосмеси. В сумме за два укоса при внесении полного минерального удобрения (Р120К90 + N60) урожайность зелёной массы травосмеси из овсяницы луговой, клевера лугового и лядвенца рогатого составила 38,5 т/га, травосмеси из тимофеевки луговой, клевера лугового и лядвенца рогатого — 37,9 т/га. Наибольшая урожайность во второй год пользования была получена у трёхкомпонентной травосмеси из тимофеевки луговой, клевера лугового и лядвенца рогатого. При внесении полного минерального удобрения она составила 30,4 т/га. На третий год пользования травостоями наибольшую урожайность обеспечило внесение полного минерального удобрения + N60 после первого укоса под травосмесь из тимофеевки луговой, клевера лугового и лядвенца рогатого. В сумме за три укоса урожайность данной травосмеси составила 35,4 т/га. Primorskaya State Academy of Agriculture, Institute of Land Management and Agricultural Technologies, department of Agricultural Technologies 692519, Russia, Primorsky Kray, Ussuriysk, Razdolnaya str., 8a E-mail: olga.ryzhenko@inbox.ru The field experiment took place at the Primorskaya State Academy of Agriculture in 2012–2015. Two-factorial field trial included: factor A — mixtures of perennial grasses: 1 — meadow fescue + red clover; 2 — meadow fescue + birdʼs-foot trefoil; 3 — meadow fescue + red clover + birdʼs-foot trefoil; 4 — common timothy + red clover + birdʼs-foot trefoil; 5 — smooth brome+ birdʼs-foot trefoil; factor В — mineral background: 1 — no fertilizers (control); 2 — Р120К90; 3 — Р120К90 + N60. The highest productivity was observed in the first cut influenced by littoral climate and plant biology. Three-component mixtures provided the highest yield in the first year. Meadow fescue mixed with red clover and birdʼs-foot trefoil produced 38.5 t ha-1 of green mass for two cuts when applying Р120К90 + N60, the mixture of common timothy, red clover and birdʼs-foot trefoil — 37.9 t ha-1. The latter performed the best in the second year. On the background of Р120К90 + N60 its yield amounted to 30.4 t ha-1. Application of Р120К90 + N60 after the first cut resulted in the highest productivity of common timothy combined with red clover and birdʼs-foot trefoil in the third year. This mixture produced 35.4 t ha-1 in total for three cuts.

ANALYSIS OF ANTROPOGENIC CHANGES OF STRUCTURAL AND AGGREGATE COMPOSITION OF IRRIGATED MEADOW-BROWN SOILS (ANTHROSOLS) IN THE REPUBLIC OF ARMENIA

From the results of the research, it becomes clear that the elements of the strict elements in these lands are generally unstable and the lands do not have a welldefined stereotype. As compared to irrigated meadow brown soils, the number of water-resistant aggregates is somewhat lower in the longitudinal irrigated soils, and the grid is different in size. It is clear from the studies that the arable lands are strongly crushed, because of the continuity of the soil and other mechanical cultures, as the soil structure is interrupted by cutting down and working on the working parts of the soil and processing tools. In order to improve the sturdy and aggregate composition of irrigated meadow brown soils, increase fertility, efficient use and maintenance, it is necessary to develop and implement a full scientifically justified agro-technical system.

INVESTIGATION OF PHOSPHATE-ION RETENTION STRENGHT IN SOME TYPES OF KAKHETI SOILS

The presented article describes the soil types existing in east Georgia, particularly in several villages of Gurjaani Municipality-Vazisubani, Kalauri, Mukuzani, Shashiani. Meadow-brown and brown soils represent good soil types for viticulture development in Kakheti. The vineyards cultivated on these soils produce such wellknown wines as Tsinandali, Vazisubani, Mukuzani, Akhasheni, Gurjaani, Manavi. The study explores brown carbonate and meadow-brown soil lab tests to examine the absorption of phosphate ions by them. The study showed that the amount of phosphorus deposited through soils is sufficiently absorbed under various conditions, having a positive effect on the amount of crop. Was compared the rates of phosphate absorption in these soils with the efficiency of phosphorus fertilizers, which showed that the higher the absorption of phosphorus, the lower the amount of phosphorus available to the plant and the lower the yield, and the lower the strength of phosphorus retention, the higher the amount of phosphorus to be consumed by the plant and the higher the yield. But under the conditions of high cultivation degree, the strength of phosphorus absorption became weak, resulted in a large amount of exchangeable and movable phosphates already existing in the soil, which is available to the plant. So, the efficacy of phosphorus fertilizers on such soil is weak. The speed of phosphorus absorption in the soil of Gurjaani municipality villages is satisfactory. However, in case of a high degree of cultivation (or in case of excess fertilization), the degree of phosphorus retention decreases. Accordingly, phosphorus-containing fertilizers should be used within strictly controlled limits.

Investigation of phosphate-ion retention strenght in some types of Kakheti soils

The presented article describes the soil types existing in east Georgia, particularly in several villages of Gurjaani Municipality-Vazisubani, Kalauri, Mukuzani, Shashiani. Meadow-brown and brown soils represent good soil types for viticulture development in Kakheti. The vineyards cultivated on these soils produce such wellknown wines as Tsinandali, Vazisubani, Mukuzani, Akhasheni, Gurjaani, Manavi. The study explores brown carbonate and meadow-brown soil lab tests to examine the absorption of phosphate ions by them. The study showed that the amount of phosphorus deposited through soils is sufficiently absorbed under various conditions, having a positive effect on the amount of crop. Was compared the rates of phosphate absorption in these soils with the efficiency of phosphorus fertilizers, which showed that the higher the absorption of phosphorus, the lower the amount of phosphorus available to the plant and the lower the yield, and the lower the strength of phosphorus retention, the higher the amount of phosphorus to be consumed by the plant and the higher the yield. But under the conditions of high cultivation degree, the strength of phosphorus absorption became weak, resulted in a large amount of exchangeable and movable phosphates already existing in the soil, which is available to the plant. So, the efficacy of phosphorus fertilizers on such soil is weak. The speed of phosphorus absorption in the soil of Gurjaani municipality villages is satisfactory. However, in case of a high degree of cultivation (or in case of excess fertilization), the degree of phosphorus retention decreases. Accordingly, phosphorus-containing fertilizers should be used within strictly controlled limits.

The influence of different systems of fertilizer on the microelement’s composition of soil and grain of winter wheat in Primorsky Krai

This paper presents the effect of the aftereffect of mineral, organic and calcareous fertilizers on the agrochemical and environmental indicators of meadow-brown bleached soil of Primorsky Krai. The accumulation of microelements by the winter wheat grain is considered according to the variants of experience. Field experiments were carried out in 2011-2014 in the crop rotation of the agrochemical station of Federal Scientific Center of Agrobiotechnology in the Far East named after A.K. Chaika. The content of trace elements in soil and grain was determined on a Shimadzu AA-6200, atomic adsorption spectrophotometer. According to the results of our research, it was revealed that the aftereffect of various fertilizer systems affected the content of a number of gross and mobile forms of microelements in the studied soil. It is established that the soil does not prevent the accumulation of mobile forms of nickel, lead, cadmium, zinc, copper and cobalt in it. The ability to resist contamination of the food chain (system barrier), that is, the manifestation of the protective mechanisms of the grain, from nickel, copper and cobalt varies only slightly according to the variants of experience. For lead, cadmium and zinc, the barrier of the system is in the moderate degree of dispersion of data on the variants of experience, showing more effective protective capabilities on the variant with the aftereffect of the lime-organic fertilizer system, where the content of the latter reaches its maximum values.

Development direction of the soil-formation processes for reclaimed soda solonetz-solonchak soils of the Ararat valley during their cultivation

Abstract The data of the article show that the long-term cultivation of reclaimed sodium solonetz-solonchak soils entails to further improvement of their properties and in many parameters of chemical compositions of soil solution and soil-absorbing complex they come closer to irrigated meadow-brown soils in the period of 15–20 years of agricultural development. The analysis of the experimental research by the method of non-linear regression shows, that for the enhancement of some yield determining parameters to the level of irrigated meadow-brown soils, a time period of 30–40 years of soil-formation processes is needed and longer time is necessary for humidification. The forecast of soil-formation processes for the long-term period, allows to reveal the intensity and orientation of development of the specified processes and to develop the scientifically-justified actions for their further improvement.

Bulk chemical composition of the mountainous meadowy brown soils of the Ukrainian Carpathians and processes of its transformation

The features of the bulk chemical composition of mountainous meadowy brown soils and anthropogenically-modified soils of the Svydovets and Chornogora arrays of the Ukrainian Carpathians are investigated. The ratio of the oxides content of the most important chemical elements of the mineral part of mountainous meadowy brown soils and parent material is determined. The basic transformation processes of the mineral part of the studied soils and parent material are established. The peculiarity of the bulk chemical composition of meadow brown soils is the high content of silicon oxides, and the high content of aluminum oxides and iron oxides. Their total content is within 94 %. This indirectly indicates a significant chemical homogeneity of the soil with the parent material. The relative accumulation of SiO2 in the upper genetic horizons of the soil profile is due to the physical disintegration of silicate rocks. Its relative bulk content is gradually reduced from 76.10–77.43 % to 72.28–76.93 % in the transition to a parent material. It was established, that the removal of sesquioxides beyond the boundary of the soil profile leads to the formation of a depleted soil profile on aluminum oxides and iron oxides, as we compare with unchanged parent material. Absolute values of the indicators of leakage factor of alkaline earth metals grow in the direction towards to the parent material. This indicates about intensive development of erosion processes in the upper part of the soil profile. This is due to the physical and chemical disintegration of aluminosilicates and the removal of compounds of disintegration into the lower soil genetic horizons. The analysis of the results of balance of bulk reserves of oxides testified, that during the formation of the mountainous meadowy brown soils of the Ukrainian Carpathians, oxides of trivalent metals (aluminum and iron) and compounds of alkaline earth metals are subjected to removal from the genetic horizons of the soil profile. Quantitative bulk chemical analysis didn’t show any significant differences in the material composition between the mountainous meadowy brown soils and the mountainous meadowy brown anthropogenically altered soil. Key words: mountainous meadow brown soils, bulk chemical composition, Svydovets and Chornogora arrays, Ukrainians Carpathians.

Digital soil map of the Ussuri River basin

On the basis of digital soil, topographic, and geological maps; raster topography model; forestry materials; and literature data, the digital soil map of the Ussuri River basin (24400 km2) was created on a scale of 1: 100000. To digitize the initial paper-based maps and analyze the results, an ESRI ArcGIS Desktop (ArcEditor) v.10.1 (http://www.esri.com) and an open-code SAGA GIS v.2.3 (System for Automated Geoscientific Analyses, http://www.saga-gis.org) were used. The spatial distribution of soil areas on the obtained digital soil map is in agreement with modern cartographic data and the SRTM digital elevation model (SRTM DEM). The regional soil classification developed by G.I. Ivanov was used in the legend to the soil map. The names of soil units were also correlated with the names suggested in the modern Russian soil classification system. The major soil units on the map are at the soil subtypes that reflect the entire vertical spectrum of soils in the south of the Far East of Russia (Primorye region). These are mountainous tundra soils, podzolic soils, brown taiga soils, mountainous brown forest soils, bleached brown soils, meadow-brown soils, meadow gley soils, and floodplain soils). With the help of the spatial analysis function of GIS, the comparison of the particular characteristics of the soil cover with numerical characteristics of the topography, geological composition of catchments, and vegetation cover was performed.

Comparative studies on the photosynthetic characteristics of two maize (Zea mays L.) near-isogenic lines differing in their susceptibility to low light intensity

The objective of our study was to quantify the effect of low light intensity on chlorophyll (Chl) content, photosynthetic parameters, chlorophyll fluorescence parameters and growth of two maize (Zea mays L.) near-isogenic lines (NILs) differing in their susceptibility to low light to reveal the cause of the resistance to weak light in maize. A field-experiment was conducted in the central plain of Liaohe river in northeast China (41°49′N, 123°34′E), on a meadow brown soil. Two levels of photosynthetically-active radiation (removal of 0% and 40% of sunlight) were tested on SN98A (shading sensitive) and SN98B (shading tolerant) lines. The results showed that shading lengthened the anthesis-silking interval (ASI), increased the percentage of barren stalk and reduced the percentage of silking, and shading decreased leaf Chl content, net photosynthetic rate (Pn), quantum yield of PS II (Y(II)), electron transport rate (ETR), and photochemical quenching (qP) in the two maize NILs. The shading tolerances differed between different near-isogenic lines. Maximum efficiency of PSII photochemistry under dark-adaption (Fv/Fm) of SN98B was increased under low light intensity, meanwhile relatively more stable contents of Chl, Pn, Y(II), ETR, and qP were able to enhance light-use efficiency and reduce the dissipation of light energy, which relieved the reduction in photosynthetic efficiency which caused reduced production of ear assimilative products, thus resulting in a smaller reduction in percentage of barren stalk in SN98B under shading. These fidings demonstrate that low light intensity depressed photosynthetic activity and growth of SN98A more than that of SN98B. SN98A could be more restricted by limited carbon assimilation, leading to the production of barren stalks in low light intensity than that of SN98B. Therefore, improvements in light-harvesting and -use capability and increasing ear filling under low light intensity stress might be important characteristics for plant breeders. Selection of SN98B as a shade-tolerant germplasm for breeding in maize would alleviate the problem of barren stalk development under low light intensity.

Genetic and agroindustrial features of meadow brown irrigated soils of Republic of Armenia in terms of climate change and desertification

Аbstract On the territory of the Republic of Armenia the irrigated meadow-brown soils evolve within the slightly sloping piedmont parts of the Ararat plain, in the conditions of the prolonged irrigation process and semi-hydromorphic or automorphic humidification. In this territory the primary soil formation proceeded in the conditions of the capillary ground humidification, but much later groundwater and capillary fringe detached from the soil layer and soil formation proceeded in the automorphic conditions, under the influence of irrigation. This work is dedicated to the study of the causes of degradation and desertification of irrigated meadow-brown soils of the Republic of Armenia. It is shown that the prolonged and indiscriminate use of these soils of the Ararat plain leads to the degradation and desertification. Studies show that some negative changes are observed in these soils that adversely affect agricultural crop yields. In particular, by comparing new- and old-irrigated variants, a noticeable reduction of humus content and absorbed basis is being observed in the arable layer of soils. The prolonged irrigation helped compact the soil mass at a considerable death, as well as leach or redistribute the part of products of the soil formation. The accumulation of silt fraction in the upper horizons is mainly due to the prolonged irrigation of these soils by muddy irrigation waters. In the case of prolonged and indiscriminate use the destruction of agronomically valuable structure and reduction of the content of water-stable aggregates occur in humus horizons. This paper provides suggestions of the ways for improving and increasing the fertility of these soils in the conditions of global climate change.