Biochemical characteristics of bread wheat genotypes related to SSR markers in moisture stress conditions

Field identification of drought tolerant wheat genotypes using canopy vegetation indices instead of plant physiological and biochemical traits

Introduction Drought stress is one of the most important abiotic stresses all around the world. The aim of breeding studies and breeding for resistance to drought is that breeders seek to identify varieties and genetic resources to drought resistant and comparison of drought resistance among the varieties and the introduction of superior varieties to farmers. Drought or imbalance between supply and demand for water is one of the most important limiting factors affecting crop production which is very important in this context, effective and economic use of water resources especially for areas with arid and semi-arid climatic conditions which covers about two-thirds of the total area of Iran (Shahram & Daneshi, 2005). Breeders have been trying that by testing different varieties under normal and stress conditions to identify varieties and use them to plant breeding programs. Cowpea (Vigna unguiculata L. Walp), a member of the family leguminous (Fabaceae) is a crop grown under the tropical and sub-tropical areas covering Africa, Asia, South America, and parts of Southern Europe and United States (Singh et al., 1997). Dry seeds of cowpea contain 20-25% protein, 1.8% fat, and 60.3% carbohydrate and are rich sources of iron and calcium (Majnoon Hoseini, 2008). In this study, various drought tolerance indices were used to identify drought resistant in varieties. Indices included drought tolerance, Tolerance Index (TOL), Mean Productivity (MP), Geometric Mean Productivity (GMP), Stress Susceptibility Index (SSI), Yield Stability Index (YSI), Yield Index (YI), Stress Tolerance Index(STI), and Harmonic Mean (HM) (Ahmadi et al., 2000; Fernandez, 1992; Safari et al., 2007; Bouslama & Schapaugh,1984; Gavuzzi et al.,1997). Materials and Methods In order to study and determine the most effective traits, drought tolerance indices and identify tolerant genotypes in vegetative drought stress on the cowpea genotypes, All 32 cowpea genotypes were cultivated in a randomized complete block design with three replications which each replication consisted of 32 experimental units, each unit or plot, three lines with a length of two meters with line spacing of 70 cm were planted. The distance between rows of plants, 10 cm and 50 cm was considered the distance between each plot, in two separate experiments including normal irrigation and water stress conditions. The study was conducted at Experimental Research Farm, University of Tehran, Karaj Agricultural Research Institute at College of Agriculture and Natural Resources in Karaj, Tehran, Iran during 2014. Drought stress was imposed by doubling the irrigation time about 50 days after planting against normal irrigation on thirty-two cowpea genotypes. Evaluation of drought resistant in different genotypes was conducted using eight indices including Tolerance Index (TOL), Mean Productivity (MP), Geometric Mean Productivity (GMP), Stress Susceptibility Index (SSI), Yield Stability Index (YSI), Yield Index (YI), Stress Tolerance Index (STI), and Harmonic Mean (HM). Results and Discussion Analysis of variance showed that there is a significant difference between genotypes for all the indices of drought tolerance and grain yield in both normal and stress conditions (P0.01). This result suggested that the genetic variation among genotypes is capable of selection for drought tolerance. A simple calculation of statistical parameters (mean and standard deviation) for drought tolerance indices indicated that there is a great diversity among the study genotypes which it can be used as rich genetic resources to help breeders to improve and identify resistant varieties. The average yield of all genotypes under drought stress and normal irrigation condition was Ys = 83.57, and Yp =101.82, respectively. Significant differences between two different conditions indicated that cowpea plant has a high potential for tolerance under drought stress condition. TOL index revealed the lowest average value among various indices (TOL =18.24). The low level of stress tolerance index shows a high relative tolerance genotype. In fact, stress tolerance index showed the changes of stress condition in genotypes. It means that genotypes with low TOL index indicate less changes and genotypes with high TOL index show more changes. Correlation coefficient was calculated to determine the relationship between grain yield and drought tolerance indices. The STI, MP, HM and GMP indices which have the most positive and significant correlation with grain yield under stress and non-stress conditions were introduced as the best indices for screening tolerant genotypes to drought and high-yielding in both environmental conditions. Using Biplot scatter graph in 32 cowpea genotypes and according to genotypes situation in Biplot display, genotypes 998, 313, 291 and 7 were identified as tolerant genotypes with high-yield. Cluster analysis based on investigated indices and yield under drought stress and non-stress conditions showed that genotypes were grouped in four clusters and most of the drought tolerant genotypes with high yield were grouped in the second cluster، while most of drought sensitive genotypes were grouped in the fourth cluster. Conclusions In this study, genotypes showed high genetic diversity in terms of drought tolerance using drought tolerance indices. Based on the results obtained in this study genotypes 291, 7, 313, and the Mashhad cultivar (998) can be proposed as drought tolerant genotypes.

Pearl millet (Pennisetum glaucum (L.) R.Br.) is a resilient crop suiting the harshest conditions of the semi-arid tropics, in which we assessed possible relationships between crop tolerance, anti-oxidative enzyme activity and plant/soil water status. Biochemical acclimation and cell homeostasis traits have been proposed as critical for the drought tolerance of crops, but their limited practical application in breeding so far suggests that the role of biochemical acclimation for drought tolerance is still unclear. Previous research may have been of limited value because it has not approached biochemical acclimation from the angle of plant water relations. Four pearl millet genotypes, contrasting for terminal drought tolerance, were evaluated (sensitive H77/833-2, tolerant PRLT2/89-33 and two near isogenic lines carrying a terminal drought tolerance quantitative trait locus) under water-stress (WS) and well-watered (WW) conditions in a lysimetric system that simulates field-like conditions. We assessed the genotypic variation and relationship between photosynthetic pigments (chlorophylls a and b and carotenoids), antioxidative isoenzymatic spectrum (superoxide dismutase, ascorbate peroxidase and catalase), physiological traits (soil moisture available, normalised transpiration, stay-green score and water extraction) and biomass and yield. Biochemical traits investigated were tightly related among each other under WS conditions but not under WW conditions. Two major ascorbate peroxidase isoforms (APX6&7), whose variation in both water regimes reflected the presence/absence of the drought tolerance quantitative trait locus, were identified, but these did not relate to yield. Both, yield and biochemical traits under terminal drought stress were closely related to the traits linked to plant/soil water status (soil moisture available, normalised transpiration, stay-green score and water extraction), whereas yield and the biochemical indicators were not correlated, except for one. It is concluded that there is no direct effect of biochemical traits on yield parameters since both are consequences of soil-plant water status and their putative relation appear to be secondary - through plant/soil water status.

In this study, the role of selenium nanoparticles (SeNPs, 10 mg·L−1) has been investigated in modulating the negative effects of drought and heat stresses on eight bread wheat (Triticum aestivum L.) genotype seedlings. Those genotypes included Giza-168, Giza-171, Misr-1, Misr-3, Shandweel-1, Sids-1, Sids-12, and Sids-14. The study included six treatments as follows: regular irrigation with 100% Field Capacity (FC) at a temperature of 23 ± 3 °C (T1), drought stress with 60% FC (T2), heat stress of 38 °C for 5 h·day−1 (T3), foliar spray of 10 mg·L−1 of SeNPs only (T4), a combination of drought stress with foliar spray of 10 mg·L−1 of SeNPs (T5), and heat stress with foliar spray of 10 mg·L−1 of SeNPs (T6). The experiment continued for 31 days. Foliar application of SeNPs improved the plant growth, morpho-physiological and biochemical responses, and expression of stress-responsive genes in wheat (T. aestivum L.) seedlings. Overall, morpho-physiological traits such as plant height (PH), shoot fresh weight (SFW), shoot dry weight (SDW), root fresh weight (RFW), and root dry weight (RDW) of wheat genotypes grown under different conditions ranged from 25.37–51.51 cm, 3.29–5.15 g, 0.50–1.97 g, 0.72–4.21 g, and 0.11–1.23 g, respectively. From the morpho-physiological perspective, drought stress had a greater detrimental impact on wheat plants than heat stress, whereas heat stress significantly impacted the expression of stress-responsive genes. Stress responses to drought and heat varied between wheat genotypes, suggesting that different genotypes are more resilient to stress. Exogenous spraying of 10 mg·L−1 of SeNPs improved the photosynthetic pigments, photosynthetic rate, gas exchange, and transpiration rate of wheat plants and enhanced drought and heat tolerance by increasing the activity of antioxidant enzymes including catalase (CAT), ascorbate peroxidase (APX), and superoxide dismutase (SOD) and the expression level of stress-responsive genes. Our results showed that spraying wheat seedlings with 10 mg·L−1 of SeNPs enhanced SOD activity for all genotypes as compared to the control, with the Sids-12 genotype having the highest value (196.43 U·mg−1 FW·min−1) and the Giza-168 genotype having the lowest (152.30 U·mg−1 FW·min−1). The expression of PIP1, LEA-1, HSP70, and HSP90 stress-responsive genes was more significant in tolerant genotypes (Giza-171 and Giza-168) than in sensitive ones (Misr-1 and Misr-3) in response to drought and heat stresses. Under stress conditions, the shoot and root fresh weights, photosynthetic pigment content, stomatal conductance (SC), and transpiration rate (TR) were positively correlated with plant height (PH), while root and shoot dry weights, malondialdehyde (MDA), proline, hydrogen peroxide (H2O2), and APX were negatively correlated. Multivariate analysis and biplot results revealed that genotypes Giza-168, Giza-171, Sids-12, and Sids-14 performed well in both stress situations and were classified as stress-tolerant genotypes. These best genotypes may be employed in future breeding projects as tools to face climate change. This study concluded that various physio-biochemicals and gene expression attributes under drought and heat stress could be modulated by foliar application of SeNPs in wheat genotypes, potentially alleviating the adverse effects of drought and heat stress.

Phoenix dactylifera L. and Medicago sativa L. are two important crops, which play economic, social, and ecological roles in oasis ecosystems. However, the ecosystems where these plants grow are subjected to drought and salinity, which are the main limiting factors for their productivity. The present study was carried out to evaluate the date palm and alfalfa response to drought and salinity stresses and to study the effect of arbuscular mycorrhizal fungi (AMF) and compost in enhancing the drought and salt tolerance. Date palm seedlings were grown under well-watered (75% field capacity: FC) and drought stress (25% FC) conditions with and without AMF inoculation on the one hand. On the other hand, date palm and alfalfa seedlings were grown under non-saline and saline conditions (0 and 240 mM NaCl; 0 and 120 mM NaCl respectively) with and without AMF inoculation and compost addition. Growth, mineral, physiological, as well as biochemical traits were evaluated in this study. Plant growth traits especially shoot and root dry weight were negatively affected by drought and salt stress. Nevertheless, mycorrhizal and composted plants showed higher growth parameters under drought and salt stress conditions compared to the untreated plants. AMF and compost mitigated the decline of P, K+, and Ca2+ concentrations induced by drought and salinity. Besides, AMF inoculation improved physiological traits through elevating photosynthetic efficiency, stomatal conductance, and leaf water potential under the two abiotic stresses. Furthermore, drought and salt stresses caused an increment in the antioxidant enzymes activities (superoxide dismutase, catalase and peroxidase, as well as ascorbate peroxidase). However, AMF inoculation induced further increase of these activities. In conclusion, colonization with AMF and compost addition could protect date palm and alfalfa plants against the negative drought and salt stress effects by mitigating their oxidative damage and improving their nutrient acquisition.KeywordsArbuscular mycorrhizal fungiCompostDrought stressSalt stressGrowthOxidative stressToleranceDate palmAlfalfa

The physiological basis of genetic variation in drought response and its association with forage yield and drought tolerance indices is not clear in sainfoin (Onobrychis viciifolia Scop.). In this study, 100 sainfoin genotypes from 10 ecotypes were clonally propagated and evaluated under non‐stressed and water deficit conditions during 2 yr. Physiological traits including chlorophyll a, chlorophyll b, total chlorophyll, carotenoid content, proline content, relative water content (RWC), catalase (CAT), ascorbate peroxidase (APX), superoxide dismutase (SOD) activity, dry matter yield (DMY), and stress tolerance index (STI) were studied. Large genotypic variation was observed among ecotypes for most of the studied traits indicating that selection in this germplasm would be useful. The results showed that water deficit greatly influenced physiological traits that affected forage production. Water deficit decreased DMY and RWC while significantly increasing carotenoid content, free proline content, CAT, APX, and SOD activity in both years. The relationship between dry matter yield and STI with proline content showed that ecotypes with high DMY and STI under water deficit conditions had higher proline accumulation in their leaves. With regard to the STI and principal component analysis (PCA), ecotypes Baft, Najafabad, and Sirjan were found to be drought tolerant or moderately drought tolerant. These ecotypes showed significantly higher values for proline content under water deficit conditions.

تنش خشکی یک تنش غیرزنده است که به عنوان یکی از عوامل مهم کاهش‌دهنده رشد محصولات کشاورزی در بیشتر نقاط جهان مخصوصا ایران بوده و منجر به تنش اکسیداتیو می‌شود. به‌منظور بررسی تأثیر سطوح مختلف تنش خشکی بر برخی صفات ویژگی‌های بیوشیمیایی، پژوهشی در گلخانه تحقیقاتی دانشکده کشاورزی زابل به‌صورت آزمایش فاکتوریل در قالب طرح کاملا تصادفی با سه تکرار در سال 1395-1396 انجام گرفت. فاکتور اول گونه‌های گندم (تائوشی، اسپلتوئیدز، اورارتو، شبرنگ، بهرنگ، سیستان، ارگ) و فاکتور دوم سطوح آبیاری (90، 70، 50 و 30 درصد ظرفیت زراعی) بودند. نتایج نشان داد که اثر تنش خشکی بر غلظت پروتئین، کلروفیل a، b، کاروتنوئید، آنزیم کاتالاز، سوپر اکسید دیسموتاز، آسکوربات پراکسیداز و مالون دی‌آلدئید تأثیر معنی‌داری داشت. این در حالی است که با افزایش تنش میزان آسکوربات پراکسیداز متغیر بود به‌طوری‌که ابتدا افزایش و سپس کاهش یافت. این وضعیت نشان‌دهنده فعال شدن سیستم آنتی‌اکسیدانی در گونه‌های مختلف گندم برای افزایش تحمل به خشکی است. پروتئین، کلروفیل و کاروتنوئید با افزایش تنش خشکی تا سطح 50 درصد ظرفیت زراعی ابتدا افزایش و با شدیدتر شدن تنش باعث کاهش این مقادیر شد. احتمالا فعالیت آنزیم‌های آنتی اکسیدانی مانع از تجزیه پروتیئن و سایر اجزاسلولی شده است. در این تحقیق رقم شبرنگ نسبت به دیگر ارقام برتری داشت در حالی که کمترین مقادیر مربوط به گونه هگزاپلوئید سیستان بود.

During the cropping season 2016-2017, an experiment was conducted in a split plot design to study the response of 25 wheat genotypes to drought stress under irrigated and minimal irrigation conditions. Different drought tolerance indices for 25 bread wheat (Triticum aestivum L.) genotypes were evaluated. The calculation drought tolerance indices was based on the grain yield of wheat under irrigated and water stress conditions. The result indicated a significant effect of drought stress on the yield of different wheat genotypes based on mean values of different drought tolerance indices. Among the studied different indices, mean productivity (MP), stress tolerance index (STI), and geometric mean productivity (GMP) were more efficient to discriminate between drought sensitive and drought tolerant genotypes based on the calculation of correlation coefficient and multivariate analysis. Twenty-five genotypes were classified into tolerant and susceptible groups through drought tolerance indices using cluster analysis. Among the genotypes, C-306, WH 1236, WH 1235, and GW 477 having higher yields under drought conditions which showing their stability under stress conditions. The most yield stable genotypes under adverse environment were identified by multivariate analysis of drought tolerance indices individually or in combination. From the result, we concluded that GMP, MP and STI are more efficient drought tolerance indices among other indices to identify stable genotypes under stress conditions.

BackgroundA primary threat to food security stems from the expanding global population and climate change, which have increased the frequency of droughts. Owing to shifting climatic conditions, abiotic stresses such as severe drought are intensifying, reducing wheat productivity. This study aimed to evaluate the response of elite drought-tolerant wheat genotypes to water deficit stress by analysing agronomic and physio-biochemical traits, with the goal of identifying promising genotypes for breeding.MethodsTwenty wheat genotypes sourced from various national and international drought-tolerant nurseries, including a benchmark variety, were tested under water deficit and well-watered conditions over two consecutive years. The data collected included agronomic traits such as plant height (PH), days to heading (DH), days to anthesis (DA), days to physiological maturity (DPM), canopy temperature, SPAD values at different growth stages, intercepted photosynthetically active radiation above the canopy (IPARAC) and on the ground (IPAR OG), yield stability index (YSI), stress tolerance index (STI), stress index (SI), leaf area index (LAI), spike length (SL), grains per spike (GPS), 1000-grain weight (TSW), grain yield (GY; t/ha), and biomass yield (BY; t/ha).ResultsTo streamline the study, two years of aggregated data were analysed for each parameter. Drought tolerance was assessed based on grain yield, and multitrait genotype‒ideotype distance (MGIDI) indices were employed to select drought-tolerant wheat genotypes. Significant differences were observed among the wheat genotypes across all measured parameters under both conditions. Under normal conditions, correlation analysis revealed that grain yield (GY) and biomass yield (BY) had the strongest positive relationship (r = 0.75**), followed by TSW, LAI, GPS, SL, PH, DPM, and DA. In contrast, under water deficit stress, BY exhibited a notable correlation with plant height (PH) (r = 0.42). Under both irrigated and water deficit stress situations, GY had positive and substantial correlations with PH, DA, DPM, GPS, SL, the STI, and the YSI. Two of the ten main components (PCs) accounted for 52.3% and 50.4% of the overall variation under water deficit and well-watered conditions, respectively. Additionally, the genotypes were separated into three clusters via a cluster heatmap, and the most tolerant genotypes (E38, E40, E41, E35, and E33) were found to be in cluster 3, which revealed their genetic relatedness. Genotypes E9 and E29 were found to be sensitive to water deficit, whereas genotypes E40, E38, and E35 were drought tolerant, according to tolerance indices.ConclusionPlant breeders may find the MGIDI useful for selecting genotypes on the basis of a variety of characteristics because it is a straightforward and robust selection method. Among the 20 wheat genotypes, the most stable and productive were E38, E30, E35, E40, and E34, according to an analysis of MGIDI for diverse settings. This was likely caused by the high MPS (mean performance and stability) of specific traits under different situations. The features that have been identified can be used as genitors in hybridization procedures to create wheat breeding materials that are resistant to drought. The genotypes and features that were found to be drought tolerant could be used to create new genotypes that are resistant to drought stress.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12870-025-07355-3.

In order to evaluate and selection of drought tolerant chickpea (Cicer arietinum L.) genotypes and to identify the best indices for drought tolerance, an experiment was conducted at Agricultural Research Station of Neyshabour during 2005-2006 growing season. In this study, 150 Kabuli chickpea genotypes from Mashhad Chickpea Collection of Ferdowsi University of Mashhad, were evaluated in Augmented Design for Preliminary Yield Trials with 6 controls (including drought-sensitive variety, current cultivars and local check). Quantitative drought tolerance and susceptibility indices such as stress tolerance index (STI), stress susceptibility index (SSI), mean productivity (MP), geometric mean productivity (GMP), tolerance index (TOL) and harmonic mean (HM) were estimated based on seed yield in stress and non stress conditions. There were significant differences among genotypes for drought tolerance indices except for TOL and SSI. The highest seed yield in stress condition was found in genotypes MCC302, MCC427, MCC352, MCC1, MCC50, MCC62, MCC118 and MCC423 with 960, 905, 638, 625, 609, 602, 592, and 581 kg/ha, respectively. The highest seed yield in non-stress condition was observed in genotypes MCC312, MCC380, MCC304, MCC50, MCC117, MCC427, MCC301 and MCC311 with 2185, 1856, 1820, 1636, 1622, 1567, 1520 and 1514 kg/ha, respectively. According to the results of regression analysis, MP, STI, GMP and HM indices in chickpea were the best indices for selection drought tolerant genotypes of chickpea. Based on these results, genotype numbers of MCC50, MCC352 and MCC427 are recommended as drought tolerant chickpea genotypes. Key Words: Augmented design, Chickpea, Drought stress, Drought tolerance indices

تنش خشکی انتهای فصل از مهم‌ترین عوامل محدودکننده تولید محصولات کشاورزی است. به‌منظور شناسایی ارقام متحمل به خشکی جو از بین 79 رقم خارجی و یک رقم شاهد ایرانی و نیز تعیین ارتباط بین اجزای عملکرد با شاخص‌های تحمل به تنش، آزمایشی تحت شرایط آبیاری نرمال و تنش آبی در مزرعه تحقیقاتی دانشکده کشاورزی دانشگاه شیراز انجام شد. از بین شاخص‌های مختلف تحمل به خشکی،MP، HMP، GMPو STIبیشترین همبستگی مثبت و معنی‌دار را با عملکرد در هردو شرایط آبیاری نرمال و تنش آبی نشان دادند و به‌عنوان بهترین معیارهای تعیین ارقام متحمل تعیین گردیدند. بعلاوه، عملکرد بیولوژیک، تعداد سنبله و وزن صد دانه در هر دو شرایط همبستگی مثبت و معنی‌داری را با شاخص‌های تحمل نشان دادند. با توجه به نتایج تجزیه به مؤلفه‌های اصلی، دو مؤلفه اول توانستند درمجموع 97 درصد از تغییرات را توجیه نمایند که مؤلفه اول به‌عنوان مؤلفه مقاومت و پایداری عملکرد و مؤلفه دوم به‌عنوان مؤلفه حساسیت معرفی شدند. با توجه به آنالیزهای آماری مختلف انجام‌شده ارقام 88 و 145 به‌عنوان متحمل‌ترین ارقام شناسایی شدند. تجزیه خوشه‌ای بر اساس شاخص‌های تحمل تنش و عملکرد در هر دو شرایط تنش و بدون تنش 80 رقم موردبررسی را در چهار گروه مجزا قرارداد. نتایج این تحقیق منبع مناسبی برای استفاده در برنامه‌های اصلاحی ارقام جو پاییزه برای افزایش تنوع ژنتیکی ژرم پلاسم ایرانی و نیز تولید ارقام متحمل به خشکی فراهم می‌آورد.

Differential modulation of photosynthesis, ROS and antioxidant enzyme activities in stress-sensitive and -tolerant rice cultivars during salinity and drought upon restriction of COX and AOX pathways of mitochondrial oxidative electron transport

A comparative comprehensive assessment of varieties and promising lines of spring durum wheat in terms of adaptability, stability of yield formation, resistance to drought and stress was carried out. For this purpose, the methods for determining ecological plasticity according to S.A. Eberhart, W.A. Russel, the AMMI method for determining the interaction of the genotype environment based on the effects of additive and multiplicative interactions according to R.W. Zobel et al., and J.M. Mondo et al. were used. To establish the degree of drought resistance and stress resistance, 11 indicators (indices) were used: TOL (Endurance Index); SI (Yield Stability Index); DI (Drought Tolerance Index); STI (Stress Tolerance Index); DSI (Fisher and Maurer Drought Tolerance Index); DSI* (Modified Fisher and Maurer Drought Tolerance Index); GMP (Geometric Productivity Index); HM (Mean Harmonic); RDI (Relative Drought Index); ATI (Abiotic Tolerance Index); SDI (Drought Sensitivity Index). According to the AMMI method, the yield-stable genotypes are Gordeiforme 11-98-3, Gordeiforme 12-169, Gordeiforme 12-17-2, Gordeiforme 13-37-2, adaptive genotypes Gordeiforme 12-17-2, Gordeiforme 13-37-2, Gordeiforme 14-83-1, Jemthujina Siberia and Omskаya jantarnaya. Calculation according to the method of S.A. Eberhart, W.A. Russell differentiated the varieties into 3 groups: 1stable genotypes that respond well to growing conditions: Gordeiform 12-16-9 and Omskaya Amber; 2 – highly stable, increasing yields in proportion to improving environmental conditions: Gordeiform 12-17-2, Gordeiform 13-37-2, Fortuna 24; 3 – extensive: Gordeiform 14-83-1, Omsk topaz. The stress and drought resistance indices TOL, SI, HM, DI, STI, DSI, DSI* GMP, SDI distinguish two samples: Gordeiforme12-17-2 and Omskaya jantarnaya. According to the relative drought index (RDI), Gordeiforme12-17-2, Gordeiforme14-83-1 and Jemthujina Sibiri stand out, and according to the abiotic tolerance index (ATI), Gordeiforme14-83-1 and Jemthujina Siberia. Revealed the most stress-resistant and stable genotypes: Gordeiforme 12-17-2, Gordeiforme 14-83-1 and Omskaya jantarnaya.

وجود تنش خشکی در ابتدای فصل رشد یکی از مهم‌ترین عوامل تهدیدکننده تولید گندم کشور ‌است. طول کلئوپتل مهم‌ترین صفت مورفولوژیک در تعیین عمق کاشت، قدرت سبز کردن و استقرار گیاهچه‌ است. به منظور ارزیابی تعدادی از ژنوتیپ‌های بومی گندم نان تحت تنش خشکی در مرحله گیاهچه‌ای، آزمایشی با 35 لاین خالص در سه شرایط رطوبتی (شاهد، تنش خشکی با پلی‌اتیلن گلیکول 6 هزار در غلظت‌های 10 و 15 درصد) در قالب طرح کاملا تصادفی با سه تکرار در دانشگاه علوم کشاورزی و منابع طبیعی گرگان انجام شد. اجرا شد. صفت طول کلئوپتیل پس از هشت روز اندازه‌گیری شد. بر اساس مقادیر طول کلئوپتیل در شرایط شاهد (Yp) و شرایط تنش (Ys) شاخص‌های MP، GMP، HM، STI، SSI، YI، TOL، RSI و YSI محاسبه شدند. ضرایب همبستگی شاخص‌های تحمل به خشکی نشان داد که شاخص‌های MP، GMP، HM و STI مناسب‌ترین شاخص‌ها برای انتخاب ژنوتیپ‌های متحمل به خشکی بودند. نتایج تجزیه به مولفه‌های اصلی نشان داد که دو مولفه اول در مجموع 78/99 درصد تغییرات را در شرایط تنش خشکی 10 درصد و 99.80 درصد را در شرایط تنش خشکی 15 درصد توجیه کردند. بر اساس شاخص‌ها و نمودار سه بعدی، ژنوتیپ‌های شماره 3، 6، 11 و 24 (به ترتیب بومی کشور‌های ترکیه، افغانستان، ایران و افغانستان) به عنوان ژنوتیپ‌های متحمل به تنش خشکی در مرحله گیاهچه‌ای شناسایی شدند در حالی که ژنوتیپ‌های شماره 14، 15، 21، 30 و 35 به عنوان حساس‌ترین ژنوتیپ‌ها معرفی شدند. نمودار چند متغیره بای پلات نیز نشان داد که ژنوتیپ‌های متحمل به خشکی در مجاورت بردار‌های مربوط به بهترین شاخص‌های تحمل به خشکی قرار داشتند. از ژنوتیپ‌های بومی شناسایی شده در این پژوهش می‌توان در برنامه‌های اصلاحی گندم نان تحت شرایط تنش خشکی در مرحله گیاهچه‌ای بهره برد.

Drought‐adapted new‐generation wheat genotypes enhance production and productivity in water‐limited agroecologies, including South Africa. Therefore, drought‐tolerant wheat ideotypes need to be bred and deployed using economic traits and tolerance indices. The aim of this study was to evaluate genetically diverse wheat genotypes and select drought‐adapted lines based on yield response, tolerance indices and genetic groups using biplot analyses for breeding and production. Ninety‐eight wheat genotypes were assessed in five environments, that is, two seasons and three sites under drought‐stressed (DS) and non‐stressed (NS) growing conditions using an alpha lattice design with two replications. Grain yield (GY) was recorded, and yield‐based 10 drought‐tolerance indices were computed for genotype selection and comparison of test environments using the genotype plus genotype by environment interaction (GGE) biplot model. The mean GY values of the test genotypes in descending order across the five environments (E) were 1.59 t ha −1 (Bethlehem site in 2022, designated as BHM‐E2), 1.57 t ha −1 (Kransfontein in 2021, KRANS‐E4), 1.03 t ha −1 (Ficksburg in 2021, FICKS‐E3), 0.63 t ha −1 (Bethlehemin 2021, BHM‐E1) and 0.58 t ha −1 (Kransfontein in 2022, KRANS‐E5). The following genotypes were the best yielders: LM29, LM9 and at BHM‐E1, BHM‐E2, FICKS‐E3 and KRANS‐E4; LM59, LM63, LM66 and LM67 at BHM‐E2, FICKS‐E3 and KRANS‐E4; and LM83 at BHM‐E1, BHM‐E2 and FICKS‐E3. The genotypes LM59, LM25, LM84, LM96, LM23 and LM39 exhibited low tolerance (TOL), susceptibility index (SSI) and high mean productivity (MP), geometric mean productivity (GMP), drought index (DI), yield index (YI), yield stability index (YSI) and relative drought index (RDI) values in a desirable trend. Correlation analysis revealed a strong association ( p < 0.001) between mean GY in non‐stressed conditions ( Y p ) and drought tolerance indices such as TOL ( r = 0.87), MP ( r = 0.77), SSI ( r = 0.72), SDI ( r = 0.72), GMP ( r = 0.65) and STI ( r = 0.54). In contrast, the mean GY in stressed conditions ( Y s ) positively and significantly ( p < 0.001) correlated with YI ( r = 1.00), DI ( r = 0.97), RDI ( r = 0.73), YSI ( r = 0.73), GMP ( r = 0.51) and MP ( r = 0.41). The indices were invaluable in identifying relatively high‐yielding and drought‐tolerant wheat genotypes, and their combined use could be effective for screening drought tolerance in wheat breeding programmes. Based on GGE biplot analysis, genotypes LM6, LM9, LM30, LM64, LM83 and LM95 were discerned to be stable and high‐yielding in the test environments. Developing new breeding populations is recommended using the above complementary selections through combining ability tests and progeny selection for yield and agronomic traits performance for variety registration and release.