Stress Sensitivity Index Research Articles

Variability of Agronomic Traits of Wheat (Triticum aestivum L.) Lines in Two Agroecosystems in Indonesia

Wheat is an important agricultural commodity in Indonesia, yet the country remains heavily reliant on imports to meet domestic demand. The diverse agroclimatic conditions in the highlands and lowlands pose significant challenges for national wheat production. This study aimed to evaluate the performance of wheat lines in two distinct altitude environments: Cipanas (1120 m above sea level) and Cisarua (600 m above sea level). An augmented randomized complete block design (RCBD) assessed 50 F6 wheat lines derived from the HP1744/”Selayar” cross. The results revealed significant variability in agronomic traits attributable to altitude differences. However, genotype-by-environment (GxE) interactions were found to be non-significant for all evaluated characters. Broad-sense heritability was classified as medium for the grain-filling period in Cipanas and seed weight of the main panicle in Cisarua, while all other traits exhibited low heritability. Based on the stress sensitivity index (SSI), 14 lines (28%) were identified as tolerant to higher temperatures in the medium-altitude environment, particularly in terms of seed weight of the main panicle. These findings are of utmost importance as they underscore the need to consider genetic and environmental factors in developing wheat cultivars suitable for Indonesia’s diverse agro-climatic conditions.

Stress-Responsive Gene Expression, Metabolic, Physiological, and Agronomic Responses by Consortium Nano-Silica with Trichoderma against Drought Stress in Bread Wheat

The exploitation of drought is a critical worldwide challenge that influences wheat growth and productivity. This study aimed to investigate a synergistic amendment strategy for drought using the single and combined application of plant growth-promoting microorganisms (PGPM) (Trichoderma harzianum) and biogenic silica nanoparticles (SiO2NPs) from rice husk ash (RHA) on Saudi Arabia’s Spring wheat Summit cultivar (Triticum aestivum L.) for 102 DAS (days after sowing). The significant improvement was due to the application of 600 ppm SiO2NPs and T. harzianum + 600 ppm SiO2NPs, which enhanced the physiological properties of chlorophyll a, carotenoids, total pigments, osmolytes, and antioxidant contents of drought-stressed wheat plants as adaptive strategies. The results suggest that the expression of the studied genes (TaP5CS1, TaZFP34, TaWRKY1, TaMPK3, TaLEA, and the wheat housekeeping gene TaActin) in wheat remarkably enhanced wheat tolerance to drought stress. We discovered that the genes and metabolites involved significantly contributed to defense responses, making them potential targets for assessing drought tolerance levels. The drought tolerance indices of wheat were revealed by the mean productivity (MP), stress sensitivity index (SSI), yield stability index (YSI), and stress tolerance index (STI). We employed four databases, such as BAR, InterPro, phytozome, and the KEGG pathway, to predict and decipher the putative domains in prior gene sequencing. As a result, we discovered that these genes may be involved in a range of important biological functions in specific tissues at different developmental stages, including response to drought stress, proline accumulation, plant growth and development, and defense response. In conclusion, the sole and/or dual T. harzianum application to the wheat cultivar improved drought tolerance strength. These findings could be insightful data for wheat production in Saudi Arabia under various water regimes.

Investigating the influence of stress dependency on the evaluation of high-temperature deformation resistance in SBS-modified asphalt

The rheological responses of Styrene-Butadiene-Styrene (SBS) modified asphalt are stress-dependent, yet the underlying mechanisms and their relationship to the phase structures formed by SBS in the asphalt matrix remain unclear. To address this issue, this study utilized varying dosages of SBS to prepare binders (SBSMA), which were then characterized through fluorescence microscopy, FTIR, and rheological tests including temperature sweeps and Multi-Stress Creep Recovery (MSCR) at four stress levels. Additionally, rutting resistance of the mixtures was evaluated using wheel tracking tests, correlating the results with rheological data. The test results indicate that the formation of a three-dimensional SBS network structure within the asphalt significantly increases the Stress Sensitivity Index (SSI) by 69.5 %, thereby enhancing the binder's stress sensitivity. Based on the theory of entropic elasticity, the stress sensitivity of SBSMA is explained. The cross-linked network structure exhibits superelastic behavior under low stress but may be overstretched and reorganized under high stress, leading to weakened entropic elasticity. Furthermore, the Jnr values obtained at higher stress levels show stronger correlation (r > 0.9) with the Dynamic Stability (DS) from the wheel tracking test results. This finding suggests that entropic elasticity does not significantly improve the rutting resistance performance at the mixture level. Consequently, increasing the stress level in MSCR tests is recommended to more accurately predict the binder’s rutting performance by inhibiting the network's entropic elasticity.

Stress sensitivity mechanism of pores in unconsolidated sandstone reservoir using NMR technology

Unconsolidated sandstone reservoirs exhibit low cementation strengths. With change in the effective stress state of the reservoir, stress sensitivity damage is induced. Consequently, the crude oil productivity is affected and the overall recovery efficiency of the reservoir decreases. Hence, a systematic investigation of the stress sensitivity of unconsolidated sandstone is crucial for the efficient development of unconsolidated sandstone reservoirs. This study primarily employed nuclear magnetic resonance (NMR) to conduct stress-sensitivity experiments on unconsolidated sandstone core samples. It quantitatively characterized the dynamic changes in the damage index of pore sensitivity in unconsolidated sandstone cores under different confining pressures. This research elucidated the stress sensitivity characteristics of unconsolidated sandstone cores during the process of increasing confining pressure. The results of the laboratory study indicated a positive correlation between the experimental confining pressure and stress sensitivity index of the core samples. During the initial stages of increasing confining pressure, the stress sensitivity index increased. With continued increase in the confining pressure, the stress sensitivity damage index for smaller pore throats ranged as 4.18–30.08%, whereas the stress sensitivity damage index for medium pore throats ranged as 4.15–28.45%. Stress sensitivity primarily occurred in smaller and medium pore throats during a progressive increase in the confining pressure. The degree of stress sensitivity was positively correlated with the scale of reservoir pore-throat development, with highly permeable reservoirs experiencing a greater extent of stress sensitivity damage. The statistical results provide crucial support for optimizing mining field production systems, effectively controlling reservoir damage, and achieving the efficient development of unconsolidated sandstone reservoirs.

Evaluation of Different Genotypes of Sesame in Terms of Stress Sensitivity and Tolerance Indices in Water Deficit Conditions

Evaluation of Different Genotypes of Sesame in Terms of Stress Sensitivity and Tolerance Indices in Water Deficit Conditions

Selection of some important tobacco genotypes against waterlogging in Indonesia

Stagnant water is an environmental challenge that can have a negative impact on tobacco growth and productivity. Study on waterlogging-tolerant tobacco is still limited. Flood-resistant tobacco genotypes are needed for future agriculture. The aim of this study is to select tobacco genotypes that are tolerant to waterlogging. This study used a factorial randomized block design. The control treatment was 100% waterlogging, with subsequent treatments escalating to 120%, 140%, and 160% (Filed capacity). Waterlogging was given for 75 hours. The observation indicator is the level of wilting of tobacco leaves. Based on the stress index values obtained from the thirty-three tested genotypes, there are three categories of ability to withstand waterlogging, namely, tolerant, moderate and sensitive. Based on the results of the study analysis, it can be interpreted that the Bojonegoro 1 genotype is the only genotype that is included in the category of tolerant to waterlogging. Genotype 1 Bojonegoro was able to survive up to 73 hours with stress sensitivity index score of 0.21.

Wheat Drought Tolerance: Morpho-Physiological Criteria, Stress Indexes, and Yield Responses in Newly Sand Soils

Drought presents a major risk to wheat growth and productivity under changing climates. During the last few years, various morphological and physiological approaches were used to overcome drought stress-associated problems. Cultivation of tolerant wheat cultivars can serve as a sustainable choice to raise wheat yield under water stress. Herein, field trials were carried out at the experimental farm of Ismailia Agricultural Research Station, Egypt, in two successive growing seasons (2020/2021 and 2021/2022) to investigate the response of four Egyptian bread wheat cultivars (Misr 1, Misr 3, Giza 171, and Sakha 95) to drought stress according to morpho-physiological characteristics, yield, and stress indices. Irrigation treatments and cultivars were assigned to the main and sub-plots, consequently, in a split-plot design with three replicates. The findings revealed that in both the first and second seasons, drought drastically revoked growth vigor of shoot, growth vigor of flag leaf, relative water content (%), membrane stability index (%), photosynthetic pigments, heading (days), maturity (days), as well as yield and yield attributes: spike length, number of spikes/m2, spike weight, grain number/spike, 100-kernel weight, grain yield/m2, straw yield/m2, biological yield/m2, and harvest index of all four wheat cultivars. Conversely, drought caused a marked increase in saturation water deficit (%), carotenoids content, and NKP uptake of all four wheat cultivars in both study seasons. The current study found that all four of the wheat cultivars were drought-tolerant plants. These cultivars exhibited similar drought-tolerant behaviors, which included decreased loss in relative water content, membrane stability, and photosynthetic pigment levels, consequently reducing wheat grain yield loss under water stress. Additionally, the drought tolerance indices of Sakha 95 > Giza 171 > Misr 1 > Misr 3 were revealed by the stress sensitivity index (SSI), mean productivity (MP), stress tolerance index (STI), and yield stability index (YSI). In conclusion, Misr 3 was the least tolerant wheat cultivar and Sakha 95 was the most tolerant. These results can be applied to breeding programs by plant breeders.

Coupling model of gas-water two-phase productivity calculation for fractured horizontal wells in tight gas reservoirs

Tight gas reservoirs are exploited mostly by using horizontal wells in combination with multi-stage hydraulic fracturing. Up to now, there have been plenty of studies conducted to establish a series of productivity models that consider various factors. Despite this, insufficient consideration has been given to the ramifications resulting from secondary fractures, permeability anisotropy, wellbore pressure drop, and the actual distribution of fractures. To accurately evaluate productivity, the superposition principle of potential and the conformal transformation theory are adopted to define the two-phase generalized pseudo-pressure, with consideration given to the characteristics of non-Darcy seepage in tight gas reservoirs and the effects of secondary fractures and permeability anisotropy on productivity. On this basis, the homogeneous flow model of the horizontal wellbore is introduced to establish the coupling model of gas-water two-phase productivity calculation for fractured horizontal wells. The results obtained from the empirical calculation and analysis of various factors affecting productivity are as follows. Firstly, the relative error is 5.35% between the theoretical open flow capability obtained from the proposed model and the open flow capability determined through the deliverability test, which attests to the proposed model's accuracy. Secondly, in response to an increase in gas slippage factor, fracture conductivity, the number of fractures, and the degree of permeability anisotropy, there is an improvement in the productivity of the gas well. However, with a rise in the water-gas volume ratio, threshold pressure gradient, reservoir stress sensitivity index, and the angle formed between the horizontal wellbore and the main permeability, the productivity declines. Lastly, the pressure drop along the horizontal wellbore is relatively insignificant, which has no substantial impact on fracture production. However, when the effect of secondary fractures is ignored, the predicted productivity is relatively low. This study offers theoretical direction for the application of productivity prediction and fracturing optimization design.

Effect of water-cooling shock on heat production performance of enhanced geothermal systems

ABSTRACT The heat extraction process of the Enhanced Geothermal System (EGS) faces the problem of mechanical property degradation caused by artificial cracks and surrounding rock caused by water-cooling shock. However, there are few studies considering the effect of water-cooling shock on fracture deformation and heat production performance. Therefore, a comprehensive numerical model considering water-cooling shock was established to simulate the heat extraction process of EGS. Four different scenarios were designed to analyze the influence of water-cooling shock on the heat production performance of EGS. The sensitivity analysis of several important variables affecting fracture aperture and heat production performance is carried out. The results show that compared with EGS without considering water-cooling shock, the heat extraction performance of EGS considering water-cooling shock is more reasonable. For a reservoir with an initial temperature of 300°C, the decrease of production temperature after 40 years is 3.35°C. Water-cooling shock changes the fracture aperture by degrading the elastic modulus of rocks and fractures, which affects the heat production performance of EGS. The decrease of fracture elastic modulus means that the fracture aperture increases under the same injection water pressure and confining pressure. The decrease of elastic modulus of bedrock leads to the decrease of stress sensitivity index, which inhibits the expansion of fracture aperture. Comprehensively considering water-cooling shock on reservoirs and fractures will more reasonably predict the heat production performance of EGS.

Effect of nano-intermetallic compound on creep properties and β-Sn grain recrystallization of Cu/Sn-Ag-Cu/Ni solder joints

In this paper, the nanoindentation method was used to study the creep properties of nano-intermetallic compound (nano-IMC) mixed solder joints. Furthermore, the microstructure evolution, crack initiation, and β-Sn grain recrystallization during thermal cycles were discussed. The results revealed that the addition of nano-IMC increased the nano-(Cu,Ni)6Sn5 content in the mixed solder joints after reflow, which increased the stress index, reduced the stress sensitivity index, and improved the creep resistance. During thermal cycles, cracks appeared at the corner of solder joints and substrate under cyclic stress, expanding along the solder/IMC interface with the increase in thermal cycles. Compared with the mixed solder joints, the recrystallization of SAC305 solder joints aggravated during thermal cycles. This is because of the high nano-(Cu,Ni)6Sn5 content in the mixed solder joints, which can effectively pin dislocations and inhibit the dislocation slip and rotation of β-Sn grains, thereby preventing the recrystallization of β-Sn grains. This improved the reliability of the mixed solder joints.

Toleransi varietas jagung (Zea mays) terhadap cekaman kekeringan pada fase perkecambahan dan vegetatif menggunakan tingkat konsentrasi PEG 6000

Corn (Zea mays L) is the second strategic commodity after rice. Limitations and uncertainties in water supply due to global warming are factors causing drought stress on agricultural land. One strategy to develop maize on dry land is to develop drought-tolerant varieties. This study aimed to determine the effect of PEG 6000 with different concentrations of four maize varieties on the drought stress tolerance of maize during the germination and vegetative phases. This research was from August to November 2020 at BPTP Banten and the Soil and Agro-climate Laboratory, Department of Agroecotechnology, Faculty of Agriculture, Sultan Ageng Tirtayasa University. This study used a Completely Randomized Factorial Design (CRD) which consisted of two factors and three replications. The first factor is the corn variety which has four levels, namely A1 (Nasa-29), A2 (JH-27), A3 (JH 45), and A4 (Lamuru). The second factor is the concentration of PEG 6000 which consists of 5 levels, namely B1 (Control), B2 (5%), B3 (10%), B4 (15%), and B5 (20%). The results showed that each concentration of PEG 6000 produced varying results. Increasing concentrations of PEG 6000 decreased yields on vigor index, germination, root length, plumula length, seedling dry weight, and drought stress sensitivity index.

Growth and Yield of Black Rice M4 Induced by Gamma-Rays 200 Gy Under Drought Stress

Black rice (Oryza sativa L. indica) is a functional food with high anthocyanin and dietary fiber content. Drought conditions due to significant climate change can reduce black rice production. Mutation induction using gamma-rays is among the popular approaches to plant improvement with increased genetic variability for breeding. The research aims to determine the growth, yield, and obtain drought-tolerant mutant black rice. This study used a field experiment method. It planted four selected mutant lines and control plants for each local black rice variety, Bantul, and Boyolali. The results showed that drought stress degraded growth and yield character, such as plant height, shoot dry weight, the number of productive tillers, percentage of filled grain, and inhibited flowering age. Resistance evaluation to drought stress used the stress sensitivity index (SSI). M4-By-200-01, M4-By-200-04, and M4-By-200-04 lines could become short-stemmed black rice and were tolerant to drought stress.

Experimental study on water saturation effect on coal sample permeability under different effective stresses

During the drainage and production of coalbed methane (CBM) wells, the constant changes in stress and water saturation of reservoir restrict the dynamic change of the reservoir permeability. By carrying out stress sensitivity experiments with different water saturations in coal, the correlation between permeability and the coupling of effective stress and water saturation was analyzed. The water saturation sensitivity and stress sensitivity of reservoir were evaluated by the stress sensitivity index (S), permeability damage rate (PDR), and stress sensitivity coefficient (αk), and the change law of coal permeability under different stresses with different water saturations was revealed. The results showed that the coal reservoir permeability decreased with increasing stress following a negative exponential function and decreased nearly linearly with increasing water saturation. In addition, the coal water saturation sensitivity was positively correlated with effective stress, and the coal stress sensitivity was positively correlated with water saturation. Finally, a mathematical model for predicting coal permeability that considered the impacts of water saturation and effective stress was established, revealing the controlled mechanism affecting the permeability change.

IDENTIFICATION OF HIGH-TEMPERATURE TOLERANCE OF SOME POTATO VARIETIES BASED ON STRESS TOLERANCE INDICE AND CLUSTER ANALYSIS

Potato self-sufficiency in Indonesia faces three main problems: rising air temperatures, limited availability of low-temperature land suitable for potato cultivation, and lack of high-temperature tolerant potato varieties. Therefore, it is necessary to identify the tolerance of potato variety to high-temperature. This research was conducted in two locations: the optimum temperature location and the high-temperature location, using nine varieties, are Agria, Andina, Amabile, Cingkariang, Granola L, Granola K, Margahayu, Olympus, and Tedjo-MZ. The study design uses a split plot with three replications. Differences in temperature as the main plot and varieties as subplots. Parameters observed were air temperature, growth, and yield of potato tubers. The analysis carried out were the Stress Sensitivity Index (SSI), Stress Tolerance Index (STI), Yield Stability Index (YSI), and Cluster Analysis. The results showed that there were no tolerant to high-temperature varieties. Based on the STI, only Olympus was a medium tolerant of high temperatures. Based on the Stress Sensitivity Index (SSI), four varieties are moderately susceptible to high temperatures (Olympus, Andina, Cingkariang, and Margahayu). The YSI analysis shows the same results as the SSI. The cluster analysis results showed harmony between the results of the stress index analysis and cluster analysis. Nine varieties had a high similarity (87.3%), meaning that all varieties had the same characteristics and less tolerance to high temperatures. Olympus was the more tolerant variety to high temperatures, followed by Andina, Cingkariang, and Margahayu. The four varieties consider promising potato lines in high-temperature areas.

Assessment of some sesame mutants under normal and water-stress conditions

ABSTRACT Sesame (Sesamum indicum L.) is a tropical oilseed crop that is also cultivated in arid and semi-arid environments, where drought occurs frequently. The objective of this study was to assess the performance of some sesame mutants, developed by our team through EMS-mutagenesis in 2020, under well-watered conditions and restricted irrigation by analyzing certain morphological, physiological, and agronomic attributes. The experiment was conducted in pots under field conditions according to a completely randomized design with three replications. The stress was simulated by suspending and reducing irrigation to 50% of the control, from the beginning of flowering until the appearance of the first capsule. The results showed variation attributable to genotypes, water regimes and their interaction was significant for all parameters studied, except the number of seeds per capsule. The mutants “ML2-5”, “ML2-72” and “ML2-37” were found to be the most tolerant to drought, exhibiting lowest stress sensitivity index and highest seed yield were associated with higher proline content in the leaves, more developed root system, higher chlorophyll content, and higher stomatal conductance than the rest of the mutants studied. This is the first report of sesame mutant lines with such high tolerance to drought during flowering. They could be used for developing high-performing cultivars with tolerance to drought during the flowering stage. The number of capsules per plant and stomatal conductance can be considered selection criteria to improve water-stress tolerance in sesame.

Effect of Structure and Hydrogen on the Short-Term Creep of Titanium Ti-2.9Al-4.5V-4.8Mo Alloy.

In this paper, the effect of hydrogenation, in the amount of 0.15 wt.%, on the short-term creep of a titanium Ti-2.9Al-4.5V-4.8Mo alloy in fine-grained (FG) and ultrafine-grained (UFG) states is studied at 723 K. The UFG structure was formed by the method of pressing with the change of the deformation axis and gradual temperature decrease. Creep tests are performed under conditions of uniaxial tension at a constant load for the creep rates at an interval of (10−7 ÷ 10−6) s−1. The UFG alloy’s resistance to creep under the investigated conditions is revealed to be substantially lower than in the FG state. When hydrogen presents in the alloy in a solid solution, a 1.3–2.5-fold rise in the value of the steady-state creep rate for the hydrogenated FG and UFG alloys is observed. The creep of the non-hydrogenated FG and UFG alloys is described by the creep power law. The presence of dissolved hydrogen leads to a violation of the creep power law. The values of stress sensitivity indices, steady-state creep rate, and effective creep activation energy are determined. The relationships between the hydrogenation, structure, and creep mechanisms of the alloy at the steady-state are discussed.

Achieving high-strain-rate and low-temperature superplasticity in an ECAP-processed Mg-Y-Er-Zn alloy via Ag addition

The effect of adding a small amount of Ag on the microstructure evolution and superplastic properties of Mg-Y-Er-Zn (WEZ612) alloys was systematically studied. The basal texture of the refined WEZ612 alloy produced by equal channel angular pressing was altered to a non-basal structure upon the addition of Ag. Ag addition also refined the grain size and promoted the formation of a large number of nano-14H-long period stacking ordered phases. Using high-resolution transmission electron microscopy, many nano-precipitated phases were detected on the basal plane of the Mg-Y-Er-Zn-1Ag (WEZ612–1Ag) alloy, The nano-precipitated phases on the basal plane improved the thermal stability of the alloy, lowered the deformation activation energy (Q), and improved the stress sensitivity index (m). At 523 K with a strain rate of 10−2 s−1, the Q value of WEZ612 was higher than that of WEZ612–1Ag (299.14 and 128.5 kJ mol−1, respectively). In contrast, the m value of the WEZ612 alloy (0.16) was lower than that of the WEZ612–1Ag alloy (0.46). At 623 K with a tensile rate of 10−2 s−1, the WEZ612 and WEZ612–1Ag alloys were elongated by 182% and 495%, respectively, with the latter exhibiting high-strain-rate and low-temperature superplasticity. The improved superplasticity of the WEZ612-1Ag alloy is attributed to the nano-precipitated phases, which effectively limit the cavity extension during superplastic deformation.

ارزیابی ژنوتیپ‌های گندم نان تحت شرایط تنش خشکی در مرحله گیاهچه‌ای با استفاده از شاخص‌های خشکی

Introduction The existence of drought stress at the beginning of the growing season is one of the most important threatening factors in wheat production of Iran. The coleoptile length is the most important morphological trait in determining sowing depth, emergence power and seedling establishment. The coleoptile length has been used as an effective indicator for selecting the drought tolerant genotypes in wheat breeding programs. Various indices have been developed to evaluate crop response to various stresses, including tolerance index (TOL), productivity mean (MP), geometric mean productivity (GMP), harmonic mean (HM), stress tolerance index (STI), stress sensitivity index (SSI), yield index (YI), yield stability index (YSI) and relative stress index (RSI). The efficiency of each indices depends on the breeding objectives and the target environment. Materials and methods In order to evaluate some of the landrace wheat genotypes under drought stress conditions at the seedling stage, an experiment with 35 pure lines under three moisture conditions (control, drought stress with PEG6000 10% and 15%) was conducted in a completely randomized design (CRD) with three replications at Gorgan university of agricultural sciences and natural resources.. The coleoptile length was measured after eight days. The indices of MP, GMP, HM, STI, SSI, YI, TOL, RSI and YSI were calculated based on the coleoptile length values under control (Yp) and stress (Ys) conditions. Data analysis was performed using iPASTIC: an online toolkit to estimate plant abiotic stress indices. Results and discussion In control and 10%-drought stress conditions, genotypes 11 and 2 had the highest of coleoptile length. While, in 15%-drought stress conditions, genotypes 3 and 6 had the highest of coleoptile length, respectively. Also in control and 15%-drought conditions genotypes 30 and 35 and in 10%-drought stress conditions genotypes 15 and 21 had the lowest of coleoptile length. Based on MP, GMP, HM, STI and YI indices, genotypes 2 and 11 were identified as tolerant genotypes, while genotypes 15, 21 and 30 were susceptible genotypes, under 10% drought stress conditions. Under 15%-drought stress conditions, MP, GMP, HM, STI and YI indices identified genotypes 21 and 34 as the most susceptible genotypes, whereas genotypes 30 and 35 were the most susceptible genotypes. Under three moisture conditions, the coleoptile length had the highest coefficient of correlation (positive and significant) with MP, GMP, HM and STI indices. Using three-dimensional plots, the genotypes were divided into four groups A, B, C, and D. The most appropriate indices being the ability to distinguish group A, from other groups. Group A selects genotypes that have high yield in both control and stress conditions. The result showed genotypes 3, 6, 11, 16, 19, 20 and 24 were classified as group A in both drought stress conditions. The Iranian commercial cultivars (genotypes 30, 34 and 35) placed in Group D, which indicates insufficient attention to drought stress at the seedling stage, while tolerance to terminal drought stress is one of the most important goals in wheat breeding programs of Iran. Principal component analysis (PCA) showed that the first two PCAs explained 99.78% of the variation in 10%-drought stress and 99.80% in 15%-drought stress conditions. MP, GMP, HM and STI had the sharp angles with together that it indicates high correlation among mentioned indices. Multivariate biplos showed that drought tolerant genotypes were adjacent to vectors related to the best drought tolerance indices. Conclusions Correlation coefficients of drought tolerance indices showed that MP, GMP, HM and STI were the most suitable indices for selecting of drought tolerant genotypes. Based on stress tolerance indices and 3D plots, genotypes 3, 6, 11 and 24 (originated from Turkey, Afghanistan, Iran and Afghanistan, respectively) were identified as drought tolerant genotypes at the seedling stage, while genotypes 14, 15, 21, 30 and 35 were identified as the most susceptible genotypes. The landrace genotypes identified in this study could be used in breeding programs of bread wheat under drought stress at the seedling stage.

Stress sensitivity of formation during multi-cycle gas injection and production in an underground gas storage rebuilt from gas reservoirs

Permeability sensitivity to stress experiments were conducted on standard core samples taken from Wen 23 Gas Storage at multi-cycle injection and production conditions of the gas storage to study the change pattern of stress sensitivity of permeability. A method for calculating permeability under overburden pressure in the multi-cycle injection and production process was proposed, and the effect of stress sensitivity of reservoir permeability on gas well injectivity and productivity in UGS was analyzed. Retention rate of permeability decreased sharply first and then slowly with the increase of the UGS cycles. The stress sensitivity index of permeability decreased with the increase of cycle number of net stress variations in the increase process of net stress. The stress sensitivity index of permeability hardly changed with the increase of cycle number of net stress variations in the decrease process of net stress. With the increase of cycle number of net stress variation, the stress sensitivity index of permeability in the increase process of net stress approached that in the decrease process of net stress. The lower the reservoir permeability, the greater the irreversible permeability loss rate, the stronger the cyclic stress sensitivity, and the higher the stress sensitivity index of the reservoir, the stronger the reservoir stress sensitivity. The gas zones with permeability lower than 0.3×10−3 μm2 are not suitable as gas storage regions. Stress sensitivity of reservoir permeability has strong impact on gas well injectivity and productivity and mainly in the first few cycles.

Quantitative Multiparameter Prediction of Fractured Tight Sandstone Reservoirs: A Case Study of the Yanchang Formation of the Ordos Basin, Central China

Summary Fractured reservoirs account for more than one-half of the global oil and gas output and thus play a pivotal role in the world’s energy structure. Under diagenesis, rocks become dense, and tectonic fractures easily form under subsequent tectonic movement. These tectonic fractures are the main seepage conduits of tight sandstone reservoirs and are important determinants of whether a tight sandstone reservoir can have high, stable oil and gas production. The influence of multistage tectonic movement has led to well-developed fractures in the Ordos Basin in central China. In the process of reservoir development, the effective stress on the fracture surface increases because of the decrease in pore pressure, and the fracture aperture, porosity, and permeability also change accordingly. Therefore, modeling of the dual porosity and dual permeability of fractured reservoirs requires a dynamic 4D modeling process related to time. In this paper, we propose a 4D modeling method of dual porosity and dual permeability in fractured tight sandstone reservoirs. First, the porosity and permeability distribution of the reservoir matrix are established based on reservoir modeling. Based on geomechanical modeling, the density and occurrence of natural fractures are predicted by the paleostress field. The in-situ stress field is used to analyze the fracture aperture, and the variation in the fracture aperture during the development process is analyzed along with the variation in the in-situ stress in the development process to realize 4D modeling of the porosity and permeability of fractured reservoirs. The total porosity of the fracture is 0 to 8 × 10−3%, and the principal value of the planar permeability of the fracture is 0 to 3 × 10−3 µm2; the principal value of the fracture permeability is concentrated in the direction of 65 to 70° east-northeast. The simulated fracture porosity stress sensitivity index is distributed between 0 and 0.2, and the fracture permeability stress sensitivity index is distributed between 0 and 0.4. The Young’s modulus of the rock, in-situ stress parameters, and sound velocity in the rock are important factors affecting the fracture stress sensitivity.