Soil Water Regime Research Articles

Long-term agro-hydrological simulations of soil water dynamic and maize yield in a tillage chronosequence under subtropical climate conditions

Process-based modeling addressing soil tillage effect on soil hydraulic properties is scarce since most assessments focus on static parameters (e.g., bulk density, penetration resistance, total porosity, etc.). Our goals were to (i) simulate the long-term soil water balance and the yield of rainfed maize under a tillage chronosequence, (ii) analyze the duration of the positive impacts of chiseling tillage effects on soil hydraulic properties, and (iii) compare the results produced by the agro-hydrological modeling with the static soil physical properties from earlier studies. A chisel tillage chronosequence was established in an Oxisol, i.e., at the sampling time the soil was under no-till (NT) for 0, 6, 12, 18, and 24 months after chiseling, and under 12 years continuous NT (control). Maize root length density (RLD) and soil hydraulic properties were determined for each treatment (four replications and three soil depths). Soil tillage effect on soil-water regime and maize yield were evaluated using the SWAP model integrated with the crop growth module WOFOST. The simulated scenarios included long-term (30 years) rainfed maize growth in each treatment. The simulation detected significant (P < 0.05) soil tillage effects on crop yield and soil water balance components. Actual crop transpiration (Tact) was promoted in the first crop season after chiseling, increasing crop yield by 14%, but this positive effect of chiseling lasted only one cropping season. Fresh chiseled soil increased Tact, while the 24-month chiseling interval generated larger water loss through runoff. RLD and soil hydraulic properties stratification within soil profile generated different patterns of soil drought stress response during the crop season. Both agro-hydrological modeling (dynamic approach) and individual soil physical properties assessment (static approach) from earlier studies found similar ephemeral positive effects of chiseling on soil physical properties. Nevertheless, agro-hydrological simulations were more effective in detecting soil functioning changes due to agricultural practices. Thus, it is crucial to integrate dynamic and static soil physical assessment when analyzing tillage effects on soil physical properties related to mass and energy transfer in cropped soils.

Assessment of Eight Faba Bean (Vicia faba L.) Cultivars for Drought Stress Tolerance through Molecular, Morphological, and Physiochemical Parameters

Determining and improving drought-tolerant cultivars is a major goal of plant breeding to face climate change. The productivity of faba bean in Egypt is affected by abiotic stresses, especially drought stress. This study evaluated eight Egyptian faba bean cultivars for drought tolerance under three soil water regimes consisting of well-watered (100% field capacity), moderate drought stress (50% field capacity), and severe drought stress (25% field capacity) regimes in pots under greenhouse conditions using biochemical, physiochemical, and molecular parameters. The cultivars Nubariya 1, Nubariya 3, and Giza 716 showed the highest proline content values under 50% field capacity conditions, with 4.94, 4.39, and 4.26 mmol/g fresh weights, respectively. On the other hand, the cultivars Sakha 1, Sakha 4, Nubariya 1, and Nubariya 3 exhibited the highest proline contents (7.8, 7.53, 6.17, and 6.25, respectively) under 25% field capacity treatment. The molecular profiling was conducted using SCoT and SRAP approaches. Fresh leaves were utilized to extract the DNA, and ten primers for SRAP and six for SCoT were used in the PCR procedures. SCoT and SRAP-PCR generated 72 loci, of which, 55 were polymorphic, and 17 were monomorphic. SCoT and SRAP each had 48 and 24 total loci, respectively. The average polymorphism (%) values achieved via SCoT and SRAP were 70.93% and 80%, respectively. Based on the molecular profiles, the cluster analysis identified three clusters. The first cluster comprised Giza 716 cultivars; the second cluster included Sakha 1, Sakha 3, Sakha 4, and Akba 3300 cultivars; the third cluster comprised two cultivars Nubariya 1 and Nubariya3. According to the study’s findings, Sakha 1, Sakha 4, Nubariya 1, and Nubariya 3 are remarkable parents for developing drought-tolerant faba bean genotypes. Additionally, this study concluded that SRAP and SCoT markers recreated trustworthy banding profiles to evaluate the genetic polymorphism among faba bean cultivars, which are regarded as the cornerstone for genetic improvements in crops.

Spatial variation in soil water on a hillslope with ephemeral gullies restored by different vegetation restoration modes on the Loess Plateau

Vegetation restoration in an ephemeral gully (EG) can alter the traits of soil, vegetation, and microtopography, and therefore likely influences soil water. Nevertheless, few results have been reported regarding the response of soil water regime to vegetation restoration modes in EGs in semiarid region. This research was designed to clarify the spatial variation in soil water in an EG with different restoration modes on the Loess Plateau of China. For the selected EG, the two banks of ephemeral gully were well restored by natural succession and artificial planting. Soil water content (θg) was quantified on the ephemeral gully floor (F), natural successional restored ephemeral gully top (NT), and artificial planted restored ephemeral gully top (AT) in both the vertical and longitudinal directions. A sloping farmland was selected as the control. The results revealed that θg increased significantly with soil depth (i.e., 0–1 m) and the distance from the ephemeral gully head (i.e., 0–60 m). In the vertical direction, the mean θg of the six test points of the ephemeral gully floor was 1.1 to 1.2 times greater than that of the control in each soil layer, while the mean θg of the six test points of NT and AT decreased by 12.3 % to 15.6 % and 29.2 % to 29.9 % compared to the control in each soil layer. Along the longitudinal direction, the θg (i.e., 0–1 m soil layer) abided by the pattern of F > NT > AT. The difference in θg between the three ephemeral gully units and their variations in the vertical and longitudinal directions were mainly driven by the variations in soil clay content, bulk density, organic matter content, plant root density, plant litter density, and the distance from the ephemeral gully head. The findings are useful to clarify the spatial variation in soil water and to select a reasonable vegetation restoration mode on hillslopes in semiarid regions.

Quantification of Evapotranspiration by Calculations and Measurements Using a Lysimeter

Evapotranspiration is one of the key elements of water balance in nature. It significantly influences the water supply in the unsaturated zone of a soil profile. The unsaturated zone is a water source for the biosphere. The aim of this study is to measure, calculate and analyze the course of actual evapotranspiration, precipitation and dew totals as well as the totals of water flows at the lower boundary of unsaturated zone and the change in water content in specified soil volume. The measurements are used for verifying the results of numerical simulation. The methods used in the study were chosen based on the hypothesis that dynamics of water supply changes in the unsaturated zone is the result of the interactions between atmosphere, soil and plant cover. The elements of water balance were quantified by the methods of water balance, lysimeter measurements and numerical simulation on the model HYDRUS-1D, version 4. The abovementioned parameters were quantified for the East Slovakian Lowland, with an hourly time step during the years 2017, 2018 and 2020. The measurements have shown that evapotranspiration exceeded precipitation during all monitored periods, specifically by 22% in 2017, by 14% in 2019, and by 10% in 2020. The deficit was compensated for by capillary inflow from the groundwater level and the water supply in the unsaturated zone. A verification by measurement has shown that numerical simulation is imprecise in relation to the quantification of water flows at the lower boundary of the unsaturated zone. This inaccuracy is manifested in the higher value of the actual evapotranspiration, which is on average exceeded by 11%. The performance of the mathematical model is assessed as satisfactory for the analysis of the soil water regime.

Determination of the shelterbelts influence on the average productivity of agrophytocenoses based on geostatistical analysis of spatial data and the NDVI

Shelterbelts effect positively on the elements of the microclimate, the water regime of soils, the agronomic properties of the soil, soil fertility in the agricultural landscape. The assessment of the influence of the density of shelterbelts on the overall productivity of arable land is poorly studied. In this study, the methodology for assessing of such impact with using GIS technologies is suggested. We propose to use the Normalized Vegetation Index (NDVI), as a standardized index showing the relative biomass of vegetation, averaged for each working area within the studied region for working plots of arable land with an area of more than 25 hectares in the Belgorod oblast. Paired correlation analysis between the density of shelterbelts and arable land productivity showed the weak relationship (R2= 0.124), however, the classification of the density of shelterbelts with the interval of 0.5 km/km2 allowed us to reveal the linear regression dependence y = 0.0059x + 0.5195 (R2 = 0.989) of arable land productivity from the density of shelterbelts. Taking into account that many abiotic factors can affect the yield, we additionally proposed to carry out typing to identify areas of the same type in terms of the relief of the earth’s surface, climatic conditions and productivity. To do this, the spatial clustering (K-means algorithm) was proposed to use. It was revealed that the productivity of agrophytocenoses increases by 10% with the increasing of the density of shelterbelts by 2 times with an average slope steepness of up to 2°. In physical terms, the yield of winter wheat will increase by 0.28 t/ha. Soil-protective crop rotations are an additional factor in increasing the value of the NDVI index on slopes more than 2°.

ИСПОЛЬЗОВАНИЕ ИСПАРЕНИЯ С ВОДНОЙ ПОВЕРХНОСТИ ПРИ РАСЧЕТЕ ВОДОПОТРЕБЛЕНИЯ МНОГОЛЕТНИХ ТРАВ В УСЛОВИЯХ НЕЧЕРНОЗЕМНОЙ ЗОНЫ РОССИИ

The subject of research is the development of a method for calculating the water consumption of perennial grasses using evaporation from the water surface, aimed at improving the accuracy of its determination and saving water resources, on the watersheds of the Non-Chernozem zone of Russia. The object of research on the total water consumption of perennial grasses are sod-podzolic soils and soil moisture of watershed areas, when growing forage crops. Experimental experiments were carried out on plots, in lysimeters and laboratories, in different meteorological conditions in years. Scientific research, processing and analysis of experimental data were based on the theory of groundwater movement, the method of water balance, physical modeling, and the theory of mathematical statistics. When conducting scientific research on the water regime of sod-podzolic soils during irrigation of perennial grasses, the methodology developed at the Department of "Agricultural Land Reclamation, Forestry and Land Management" of the K. A. Timiryazev Russian State Agricultural Academy of Agriculture was used. Experiments conducted in lysimeters and plots in 2012...2014 served as the basis for the development of a formula for determining the water consumption of perennial grasses using evaporation from the water surface in the watersheds of the Non-Chernozem zone of Russia.

Effects of organic composite fertilizer on soil nitrogen status and mineralization

A short-term soil incubation experiment was set up to obtain information to clarify the effect of our developed organic composite fertilizer on soil nitrogen mineralization. The composite was designed to have beneficial effects on the properties of chicken manure and to improve soil water management properties in addition to organic matter replenishment. In the incubation experiment, two different additives, bentonite, and super absorbent polymer, were used to enhance the properties of fermented chicken manure. Developed prototype products were tested in a four-week-long soil incubation experiment in two typical Hungarian soils: brown forest soil with a sandy texture and chernozem soil at two different water capacities (40 w/w % and 60 w/w %). Soil pH, and inorganic nitrogen forms, like nitrate and ammonium, were measured weekly. Furthermore, the potentially mineralized nitrogen and net mineralization rate were calculated. The applied composite was not affected the soil pH significantly in the examined period. The soil nitrate and ammonium ratio was changed during the incubation as the ammonium content in the soil decreased while nitrate content increased continuously throughout the experiment. This suggests that the incubation experiment successfully monitored the delicate balance of soil nitrogen forms. It was found that the chernozem soil type had a higher mineralization potential compared to brown forest soil due to its higher nutrient and organic matter contents. Moreover, our results pointed out that soil moisture content did not significantly affect the mineralization process. The amount of mineral nitrogen, generated per week can be described by a linear relationship for both soil types and water regimes. The composite product showed efficacy in promoting mineralization processes, particularly in soils with low nutrient status and mineralization potential.

The possibility of physico-theoretical methods in soil ecology (the case of modeling soil-climatic areas structure)

The aim of the study was to consider the possibilities of up-to-date physical and theoretical methods for solving problems of soil ecology related to the mathematical description of the regularities of the systemic organization of soil-climatic areas according to hydrothermal factors of the environment. Methods. Methodological analysis of the idealizations, hypotheses and concepts was used alongside with mathematical modeling. Results. Methodological analysis of the assumptions underlying the quantitative determination of the two traditional hydrothermal coefficients (the radiation index of dryness, R/LP, and the moisture coefficient, P/E0) justifies their attribution to the marginal (boundary) soil conditions, determined mainly by climatic characteristics. From the physico-theoretical (quantitative) point of view, this is one of the reasons for their limited applicability when considering soil and ecological problems related to the quantitative description of the relationship between the types of soil thermal and water regimes and the general climatic patterns of their distribution on the earth's surface. Based on the fundamental principle of affine similarity (a variety of the general principle of symmetry), the article suggests the new generalized variables R/Eα and P/Eβ. In these variables soil moisture evaporation E(R,P), determined for the entire range of the average long-term climatic characteristics of R (radiation balance) and P (precipitation), acts as a general reference system. The specificity of the hydrothermal response of the soil substrate is determined by the corresponding structural and functional indices of similarity α and β. The physical meaning of the new variables is that they characterize the totality of radiation energy (α) and precipitation (β) use by specific soil-forming process. Conclusions. A mathematical model, based on the functional association between the generalized variables, enables predicting new structural and functional regularities (radial and tangential) in the system of soil-climatic areas. In comparison with the climatic hydro- and thermoseries proposed by V. R. Volobuev, these regularities better describe the experimental data.

Районирование при обосновании вероятности необходимости осушения земель и методы снижения загрязненности дренажного стока

Purpose: to develop mechanisms for territory zoning according to demand for land drainage and the volume of substances leaching with drainage runoff and to identify the methods for reducing the pollution of drainage runoff. All calculations are made using the example of macrozonal zoning of drainage when growing strategically important crops: spring wheat and potatoes – using the example of the European part of Russia. Materials and methods. The justification for drainage was carried out using the bioclimatic method of V. V. Shabanov. A dimensional analysis technique and laboratory experiments on leaching soil monoliths for determining the main factors influencing the leaching of substances from soil were used. Results. A justification of reclamation measures (drainage) for regions and districts of the Russian Federation was carried out using the example of grains and potatoes. The main water protection measures reducing the polluting impact on water intakes from drainage runoff include: the creation of biological engineering structures; passive measures – precise reclamation aimed at managing the conditions for the drainage runoff formation, taking into account soil heterogeneity based on the zoning of drainage and the volume of nutrient leaching from drained lands. Conclusions. The European part of Russia has been zoned based on demand for drainage. A low degree of demand for land drainage when growing spring wheat was noted on approximately 40 % of the area and high degree was noted on 50 %. When growing potatoes, these areas account for 20 and 50 % of the area, respectively. The influence of factors on the drainage runoff formation and the volume of substance leaching was revealed. Water protection measures are proposed: construction of biological engineering structures and carrying out precise reclamation as a way to control the water regime of soils.

Features of soil water regime under spring and winter pea crops

Features of soil water regime under spring and winter pea crops

Водосберегающие поливы кукурузы на мелиорированных землях Ростовской области

Purpose: to develop a water-saving regime for irrigating corn for grain, which guarantees sustainable productivity with a shortage of water resources on the basis of field research. Materials and methods. The studies were carried out in Rostov region according to generally accepted methods. The soil of the plot is ordinary chernozem. According to water-physical and agrochemical indicators, it is suitable for crop cultivation. The experiment scheme included three options: in option 1 (control), a previously developed irrigation regime was used; in options 2 and 3, from the beginning of the growing season to the phase of tasselling, irrigation rates were given out completely (as in option 1), and then decreased by 15 and 30 %, respectively. Results. The pre-irrigation soil moisture limit in the 0–60 cm layer was maintained at the level of 70–75 % of the minimum water capacity. The soil water regime influenced the plant growth and development. The differences in the onset of plant vegetation phases were observed from the phase of tasselling. The grain firm ripe stage occurred in variant 3 earlier, then in variant 2. The largest linear growth in the flowering phase (269 cm) was recorded in variant 1, which was 3.7 and 5.2 % higher than the indicators of the variants 1 and 2, respectively. The biological yield of corn in option 1 was 12.9 t/ha, which is 10.1 and 16.3 % higher than the water-saving options. According to the calculations of economic efficiency, with a decrease in irrigation rates by 15 %, the cultivation of corn for grain is profitable. Conclusions. As a result of the research, a water-saving irrigation regime for corn for grain was developed and recommended for agricultural production, which provides for nine vegetation irrigations: the first and second – 300 cubic meters/ha each, the third – 400 cubic meters/ha, from the fourth to the ninth ones, irrigation is carried out at a rate reduced by 15 % – 425 cubic meters/ha. Irrigation rate is 3550 cubic meters/ha.

Опыт водосбережения при поливах овощных культур открытого грунта

Abstract. Purpose: on the basis of study and analysis of scientific sources to summa-rize the experience of water saving and to determine the features of modern irrigation regimes for vegetable crops in open ground. Discussion. Tomatoes and cucumbers are popular vege-table crops. The main areas of their cultivation in the country are the Southern and North Caucasian Federal Districts, where it is impossible to obtain yields without irrigation. The re-quirements of vegetable crops for moisture increase significantly during the periods of flower-ing, fruit setting and formation. Its deficiency during these periods leads to a decrease in productivity and a shortage of output. At present, both intensive irrigation with full irrigation rates and differential irrigation are practiced where irrigation is carried out with reduced irri-gation rates and the inter-irrigation periods and the number of watering are changed. An anal-ysis of the results of studies on tomato and cucumber cultivation on irrigated lands made it possible to determine that as a rule, under full irrigation, pre-irrigation soil moisture sill for these crops are maintained at least 80 % of the minimum moisture capacity. With differentiat-ed regimes, water saving is achieved by reducing the amount of irrigation water used. In this case, the differentiation criteria are the pre-irrigation soil moisture sill, the phases of crop growth and development, the depth of the calculated soil layer, the magnitude of irrigation rates, and the total evapotranspiration. The disadvantage of differentiated irrigation regimes is the lack of production, which can reach 14 % compared to the intensive irrigation regimes. Conclusions. An analysis of the water-saving experience during irrigating vegetable crops in open ground confirmed the effectiveness of differentiated irrigation regimes. Under such re-gimes, the yield decrease is not so significant, however, the most efficient use of irrigation water and higher product quality are noted. The combination of the optimal soil water regime and fertilization system contributes to the increase in the efficiency of production process of vegetable crops.

ОПТИМИЗАЦИЯ ЭЛЕМЕНТОВ ПОЧВЕННОГО ФАКТОРА УРОЖАЙНОСТИ – ОСНОВНОЕ НАПРАВЛЕНИЕ ПОВЫШЕНИЯ ЭФФЕКТИВНОГО ПЛОДОРОДИЯ ПОЧВ В АГРОЛАНДШАФТАХ СРЕДНЕГО ПОВОЛЖЬЯ

The article provides optimal indicators of the most important soil fertility regimes (food, air, water, microbiological, chemical, physical, temperature). Particular attention is paid to improving soil loosening. Based on long-term research (1988–2015), it was revealed that the optimal density of gray forest soils for cultivating crops for grain is in the range of 1.1–1.3 g/cm3 , for technical soils – 1.0–1.2 g/cm3 . For heavy loamy leached chernozem 1.2–1.3 g/cm3 and 1.1–1.3 g/cm3 , respectively. The fundamental condition for crop formation in the northern part of the Middle Volga region is productive moisture. In wet years, the amount of precipitation due to uneven distribution during the growing season, ensuring optimal soil water regime is crucial. Relatively long periods of low precipitation and high temperatures are usually observed in spring and the first half of the growing season. A very good way to improve the moisture supply of plants is to create sufficient moisture reserves in the soil using available agrotechnical and other methods and ensure their productive use throughout the entire growing season of agrocenoses. In order to optimize the indicators of the elements of the soil factor of productivity, the leading measures for their improvement are given. The connection with other productivity factors (biological, biosphere, atmospheric, cosmic) and their mutual impact on increasing the potential for their manifestation is shown. It is emphasized that the leading factor in yield is biological.

Dosadašnji značaj i uloga Poljoprivrednog fakulteta u Beogradu na razvoj i primenu melioracija u Republici Srbiji

The development of agriculture in Serbia would not have been possible without the implementation of ameliorative measures. Measures to improve the soil water regime in our country have existed throughout modern era, but very significant ameliorative practices have been implemented in the last 100 years, coinciding with the establishment of the Faculty of Agriculture at the University of Belgrade. In Serbia, after the First World War, extensive work was carried out in the field of drainage, which underwent a real expansion after the Second World War. In the period from 1950 to 1970, drainage systems were built on about 1.5 million hectares, and by 1990 the total drained area exceeded 2.01 million hectares. Alongside the construction of drainage systems, dams were built on the major rivers to protect coastal areas from flooding. A significant achievement is the construction of the Danube-Tisza-Danube water system (1947-1977), which involved complex and versatile water management in Vojvodina. The introduction of irrigation in agriculture progressed much more slowly than drainage. The total irrigated area in 1990 was about 120,000 hectares, and today, after the crisis-ridden 1990s, it amounts to about 100,000 hectares. Nowadays, it is necessary to design additional drainage systems where problems of this kind arise, whereas the potential areas for irrigation are considerably larger. Until the beginning of the 21st century, various ameliorative activities were the focus of technical and research activity: soil surveys, investigation of the soil physical and water characteristics, soil chemical amelioration , the application of horizontal pipe drainage, soil recultivation, soil conservation, introduction of large machines for pressurised irrigation and application of drip irrigation methods. More recently, modern technologies and contemporary global trends such as the use of GIS, remote sensing, soil water balance monitoring, crop cover monitoring, micrometeorological measurements, automation of irrigation systems and crop growth modelling have been introduced alongside the application of traditional methods. The last decade has been marked by researches focused on the effects of climate change on agricultural production. The importance of the Soil and Water Management department is reflected in the training of professionals who are able to keep pace with technological changes and apply them to the management of soil and water resources, from the planning and implementation of new hydromeliorative systems to the maintenance of old systems and the management of crop production.

INFLUENCE OF DIFFERENT CONDITIONS OF MINERAL NUTRITION ON YIELD OF SWEET SORGHUM SEEDS IN THE CONDITIONS OF THE SOUTHERN FOREST-STEPPE OF WESTERN SIBERIA

Sorghum occupies a significant place in world agriculture and is of particular value in intensive feed production. The selection of agricultural practices for increase of seed productivity is relevant and current, since the availability of own seeds is of decisive importance in reduction of feed production cost. The studies were carried out in Omsk region in 2013, 2015–2017 in a stationary field experiment in eight-field crop rotation. The aim of the work is to study the influence of mineral nutrition conditions on yield of sweet sorghum seeds, water and nutritional regimes of meadow-black soil in the conditions of the south of Western Siberia. The experiment included a three-factor scheme: the supply of soil with mobile phosphorus according to Chirikov (factor A) - average, 50-100 mg/kg (background 0); increased, 100-120 mg/kg (I) and 140-150 mg/kg (II); high, 150-200 mg/kg (III); phosphorus fertilizer (factor B) - P0, P60; nitrogen fertilizer (factor C) - N0, N30, N60. The field experiment was implemented by mutual method of pre-sowing application of mineral fertilizers and different levels of phosphorus in the soil. The soil is meadow-black soil, medium-thick, medium-humus, heavy loamy. The reaction of the soil environment in the arable layer is neutral, the depth of groundwater in spring is 2.86, in autumn - 3.09 m. The climate of the southern forest-steppe of Omsk region is suitable for sweet sorghum cultivation with insufficient moisture in some years and uneven distribution of precipitation during the growing season. The yield of sweet sorghum seeds ranged from 2.93 to 3.46 t/ha on average for 3 years, depending on the background, the largest yield increase was noted on 0 background (N60P60) with a natural level of mobile phosphorus and pre-sowing application of nitrogen and phosphorus fertilizers. It is possible to obtain seeds of sweet sorghum in the southern forest-steppe of Omsk region. To achieve high yields on soils with an average content of mobile phosphorus, it is necessary to use nitrogen and phosphorus fertilizers. It is also indispensable to select an early ripening variety capable of forming high quality seeds in the specific conditions of Siberia.

WATER REGIME AND EFFICIENCY OF GROWING SUNFLOWER HYBRIDS DEPENDING ON THE ELEMENTS OF DRIP IRRIGATION TECHNOLOGY

The article presents the results of experimental research on the influence of micro-irrigation system designs on the water regime, productivity, and efficiency of sunflower cultivation. Based on this, the main economic parameters of agrotechnologies of sunflower cultivation were calculated. Short-term field research was carried out in the period 2020-2022 on the lands of the Brylivske experimental field of the Institute of Water Problems and Reclamation of the National Academy of Agrarian Sciences (Kherson Region, Dry Steppe subzone). Analytical and statistical methods were used to process experimental data. The scheme of field experiments provided different options for laying irrigation pipelines of micro-irrigation systems (in the horizontal and vertical planes) and the implementation of a pulsed water supply mode (standard). The control was the variant without irrigation. According to the results of experimental studies, it was proved that the method of laying irrigation pipelines of micro-irrigation systems significantly affects the parameters of the formation of the soil water regime and the yield of sunflower hybrids in the conditions of the Dry Steppe. It has been established that the introduction of subsurface drip irrigation is more appropriate than the cultivation of sunflower hybrids, which is explained by the drought resistance of this crop. When growing sunflowers, the variant with the subsurface laying of drip irrigation pipelines provided almost identical yield parameters at lower plant water consumption coefficients. &#x0D; The minimum water consumption coefficient (1077,8 m3/t) was obtained by implementing the pulse water supply mode. The highest economic parameters of agricultural technology for growing sunflower hybrids were obtained with the subsurface drip irrigation: conditionally net profit (17,11-18,17 thousand UAH/ha), lower cost (11,03-10,90 thousand UAH/ton), and also a higher level of production profitability (31,10-32,62%) (laying irrigation pipelines every 1,0 m, regardless of the sunflower hybrid). Due to the higher grain yield and specific savings of irrigation water in the pulse mode of water supply, the highest economic parameters were achieved: gross income amounted to 80,51 thousand UAH/ha, conditionally net profit – 21,24 thousand UAH/ha, cost of 1 ton of grain - UAH 10,6 thousand and the level of profitability of production – 35,8%.

Effects of Different Land Use Patterns on Soil Water in Loess Hilly and Gully Regions of China.

Soil water is a major barrier to ecological restoration and sustainable land use in China’s Loess Hilly Region. For the restoration of local vegetation and the optimal use of the region’s land resources, both theoretically and practically, it is essential to comprehend the soil water regimes under various land use types. The soil water content in the 0−160 cm soil profile of slope cropland, terraced field, jujube orchard, and grassland was continuously measured using EC-5 soil moisture sensors during the growing season (May−October) in the Yuanzegou catchment in the Loess Hilly Region to characterize the changes in soil water in these four typical land use types. The results showed that in both years of normal precipitation and drought, land use patterns varied in seasonal variability, water storage characteristics, and vertical distribution of soil water. In the dry year of 2015, the terraced field effectively held water. During the growing season, the 0−60 cm soil layer’s average soil water content was 2.6%, 4.2%, and 1.8% higher than the slope cropland, jujube orchard, and grassland, respectively (p < 0.05), and the 0−160 cm soil layer’s water storage was 43.90, 32.08, and 18.69 mm higher than the slope cropland, jujube orchard, and grassland, respectively. The average soil water content of the 0−60 cm soil layer in the jujube orchard was 2.9%, 3.8%, and 4.5% lower than that of slope cropland, terraced field, and grassland, respectively, during the normal precipitation year (2014) (p < 0.05). Only 35.0% of the total soil water storage was effectively stored in the 0−160 cm soil layer of the jujube orchard during the drought year. There was a significant difference in the grey relational grade between the soil water in the top layer (0−20 cm) and the soil water in the middle layer (20−100 cm) under different land use types, with the terraced field having the highest similarity degree of soil water variation trend, followed by grassland, slope cropland, and jujube orchard. Slope croplands in the study region may be converted into terraced fields to enhance the effective use of rainfall resources and encourage the expansion of ecological agriculture. Proper water management practices must be employed to reduce jujube tree water consumption and other wasteful water usage in order to guarantee the jujube orchard’s ability to expand sustainably. This would address the issue of the acute water deficit in the rain-fed jujube orchards in the Loess Hilly Region.

Enzymatic and non-enzymatic response of grafted and ungrafted young European pear (Pyrus communis L.) trees to drought stress

The optimization and selection of the scion-rootstock combination are commonly based on its physiological and biochemical alterations capacity, especially in the rootstock, which is significant to elucidate the mechanisms associated with water stress tolerance. To verify the antioxidant defense systems under drought stress, two ungrafted rootstocks, `Dargazi᾿ seedling (D) and `Pyrodwarf᾿ clonal (P), and two pear scion cultivars including `Dargazi᾿ (D) and `Louise Bonne᾿ (L), that were grafted on the studied rootstocks were examined. We considered growth and chlorophyll fluorescence traits, some oxidative stress markers, and non-enzymatic and enzymatic antioxidant parameters in plants subjected to different soil water regimes. Treatments were, well-watered as control (100% FC), moderate (60% FC), and severe drought (30% FC) under greenhouse conditions. Drought stress influenced chlorophyll fluorescence contents and limited the quantum yield of PSII (Fv/Fm), mainly in P rootstock. In contrast, the highest specific leaf area (SLA), and lowest leaf mass area (LMA) was observed in the P rootstock, which indicated that the P rootstock was more sensitive to drought stress. Physiological and biochemical alterations and the main components of multivariate analysis showed that hydrogen peroxide (H2O2) and malondialdehyde (MDA) were accumulated under water deficit conditions, and P and D rootstocks showed a higher level of H2O2. We found a reduction in chlorophyll pigments, carotenoid (CAR), and ascorbic acid (AA), by drought stress, which had the highest amount in P and D rootstocks. Water stress directly influenced anthocyanin (ANT), total phenolic content (TPC), total flavonoid content (TFC), catalase (CAT), guaiacol peroxidase (GPOX), and ascorbate peroxidase (APOX) activity, especially under severe stress levels, and there was a high activity of GPOX in grafted combinations. In general, rootstocks showed more oxidative stress than grafted combinations because of the high increase in H2O2 and MDA, and response to stress by the accumulation of some enzymatic and non-enzymatic factors. However, grafted combinations mostly showed better tolerance with the enzymatic antioxidant defense system, which can be the result of resistance induced by rootstocks and the cultivar's capacity to minimize the negative effects of drought stress.

Arbuscular mycorrhizal fungi induce flavonoid synthesis for mitigating oxidative damage of trifoliate orange under water stress

Arbuscular mycorrhizal (AM) fungi can increase the tolerance of host plants to drought, whereas the intrinsic mechanisms are not still fully elucidated. Flavonoids are a kind of antioxidants to scavenge reactive oxygen species (ROS), whereas whether and how flavonoids are involved in increased drought tolerance of host plants by AM fungi is not known. Here, Funneliformis mosseae , was inoculated into potted trifoliate orange seedlings, which were subjected to adequate water and water stress conditions. The AM effect on plant growth, concentrations of flavonoid substances and total flavonoids, and activities and expression levels of enzymes related to flavonoids synthesis (clnnamate 4-dydroxylate (C4H), phenylalanine ammonialyase (PAL), chalcone isomerase (CHI), and 4-coumaroyl-CoA ligase (4CL)) in roots was analyzed, along with changes in scavenging activity of ROS by root flavonoid extracts. Compared with non-AM control, F . mosseae inoculation distinctly improved plant growth performance and increased phenylalanine, glycitin, luteolin-7- O -glucoside, and total flavonoid concentrations, coupled with the decrease in p -coumaric acid, regardless of soil water regimes. Activities of C4H, CHI, 4CL, and PAL and expression levels of PtPAL1 and Pt4CL were induced by F . mosseae inoculation under water stress. AM plants exhibited higher scavenging activity of hydroxyl radical and superoxide (O 2 •− ) by root flavonoid extracts under water stress, along with lower levels of O 2 •− and hydrogen peroxide and the degree of membrance lipid peroxidation, compared with non-AM plants. It is concluded that AM fungi accelerated flavonoids synthesis of trifoliate orange for mitigating oxidative damage under water stress. • AMF increased phenylalanine, glycitin, luteolin-7- O -glucoside, and total flavonoid concentrations, regardless of soil moisture regimes. • C4H, CHI, 4CL, and PAL activities and PtPAL1 and Pt4CL expressions were induced by AMF under water stress. • AMF plants exhibited higher scavenging activity of ROS by root flavonoid extracts under water stress. • AM fungi accelerated flavonoids synthesis for mitigating oxidative damage under water stress.

Growth and Physiological Responses of Pepper in Different Soil Water Regimes and Nitrogen Applications in a Semiarid Agricultural Ecosystem Using Surface and Sub-surface Drip Irrigation and Its Economic Returns

Growth and Physiological Responses of Pepper in Different Soil Water Regimes and Nitrogen Applications in a Semiarid Agricultural Ecosystem Using Surface and Sub-surface Drip Irrigation and Its Economic Returns