Visual selection in early stage of wheat breeding is usually implemented method. This study was conducted to compare breeders’ visual selection with normalized difference vegetation index (NDVI) selection. Three different selection protocols were used at Head Rows (HR) stage: Breeder visual, NDVI+ (high mean NDVI), and NDVI- (low mean NDVI). Some HRs were selected by both Breeder and NDVI+ (Breeder & NDVI+). Performances of HRs selected by each protocol were studied for grain yield and relationship of NDVI with yield in yield trials. 403 HRs of total 1246 HRs derived from 38 populations were selected by protocols at varying rates: 13.2% by Breeder, 10% by NDVI+, 3% by NDVI-, and 6.1% by Breeder & NDVI+. NDVI values measured at the pre-heading stage in the HR and early grain filling in the Preliminary Yield Trial (PYT) showed strong correlations with grain yield (r= 0.55** and r= 0.73**, respectively; p
This study compared the adaptation, yield and essential oil composition of five commercial Mentha piperita cultivars (Piper-1, Multimentha, Swiss, Yakima, Black Mitcham) and a newly developed Mentha arvensis clone (Arven-1) in two distinct ecologies with different climates in Türkiye (Isparta and Salihli). Fresh-dry herb, dry leaf, essential oil yields, and essential oil components (GC-MS) were analysed in two-year (2021-2022) field trials. The findings indicated that factors such as location, year, cultivar, and harvest time exerted substantial influences on yield parameters. The Salihli location, characterized by a Mediterranean climate, yielded significantly higher values than Isparta, which has a transitional climate. While the highest fresh herb and dry leaf yields exhibited variation by location ('Swiss' in Isparta, 'Yakima' in Salihli), the highest essential oil yield was consistently obtained from clone 'Arven-1' in both locations (284.8 L ha-1 in Salihli). Analysis of the essential oil components revealed that the menthol content reached up to 78.2% in the 'Arven-1' clone. In contrast, M. piperita varieties showed lower menthol content and higher menthone content. Specifically, the 'Multimentha' variety had a menthone content of 57.7%. These findings indicate that the 'Arven-1' clone of M. arvensis is suitable for menthol production in Türkiye, while M. piperita varieties produce an oil profile dominated by menthone instead of menthol in hot climates. The study demonstrates that the correct genotype and environmental matching is critically important in increasing menthol production in Türkiye and reducing dependence on menthol imports.
This study aimed to identify high-yielding and stable bread wheat genotypes through genotype × environment interaction analysis using GGE biplot methodology. A total of 160 genotypes were evaluated during the 2023 and 2024 cropping seasons at Dabat and Adet in northwestern Ethiopia using an alpha lattice design with two replications. Significant effects of genotype, environment, and their interactions (p ≤ 0.0001) were observed across all eleven agronomic traits studied. The analysis revealed that genotypes G10, G36, G52, G81, and G28 consistently combined superior grain yield with high stability across environments. Among the test sites, Dabat 2024 emerged as an ideal environment for evaluating grain yield performance. Environmental clustering further delineated two distinct mega-environments, providing valuable insights for breeders in selecting genotypes with either specific or broad adaptation. These findings highlight the utility of GGE biplot analysis in guiding wheat breeding programs toward improved yield stability and targeted genotype deployment.
Growing degree days (GDD) are widely used to describe crop development, but information on how sowing date influences thermal requirements in safflower remains limited. This study evaluated phenological development, thermal requirements and seed yield in a twelve-year field experiment (2013–2024) under semi-arid conditions in central Türkiye. Three cultivars were sown on five dates (1 March, 15 March, 1 April, 15 April and 1 May) in a split-plot design with three replications. Daily GDD was calculated using a base temperature of 5 °C and an upper threshold of 30 °C, with both minimum and maximum temperatures constrained to the threshold range. Year, sowing date, cultivar and their interactions significantly affected developmental stages, corrected GDD and seed yield (P < 0.01). Delayed sowing markedly shortened calendar time to emergence, whereas corrected mean GDD to emergence remained comparatively stable across sowing dates (92.72–96.28 °C day). Mean seed yield declined from 2399 to 838 kg ha⁻¹ from the first to the last sowing date. Daily accumulation of photothermal units produced stage-dependent differences between the earliest and latest sowings, and leave-one-year-out validation did not support the superiority of air-temperature-based GDD over 5-cm soil-temperature-based GDD. Linear mixed-effects models accounting for the experimental hierarchy further showed that several pooled associations between thermal variables and seed yield were weaker than suggested by simple correlations. Overall, early March sowing provided the highest seed yield, while threshold-corrected GDD indicated comparatively stable thermal requirements across sowing dates.
The improvement of new cotton varieties with high yield and superior fiber quality is of crucial importance for maintaining genetic diversity and meeting the requirements of the textile industry. A total of 13 different bulk populations were compared with F3/F4 evaluated in 2022 and F4/F5 in 2023 for yield and fiber quality. The experiments were designed using a split-plot design, with generations assigned to the main plots and populations to the subplots. Variance analysis indicated that generation × population interactions were significant for seed cotton yield, ginning out-turn, fiber length, fiber fineness and fiber strength. Due to high inbreeding depression and low heritability, it was determined that seed cotton yield is influenced more by environmental factors than by genetic factors. Therefore, it has been concluded that the single plant should be selected in later generations in breeding programs targeting increased seed cotton yield. (Julia × ST-468) × (Carmen × Carisma), (Carisma × Carmen) × (Gloria × Carisma), (Julia × ST-468) × (Gloria × Flash), and (ST-468 × Claudia) × (Gloria × Flash) were identified as optimal populations with high yield and superior fiber quality characteristics.
Artemisia absinthium is a known medicinal plant in Europe, Africa and also in West Asia and North America. The present research was carried out to determine the effects of phenological periods on yield and quality of A. absinthium products during 2023-2024 seasons. The study was conducted in the Lakes Region of Türkiye, an area characterized by diverse cropping systems and suitable climatic conditions for medicinal and aromatic plants, providing an appropriate environment for evaluating the phenological responses of A. absinthium. In 2022, seedlings were grown from seeds and planted as a randomized complete block design. Second- and third-years plants were harvested which was bolting, budding, flowering and maturation periods. The differences between the years and phenological period were significant for all parameters (except for essential oil yield). The highest fresh and dry herb yield were 12560.2 and 5520.8 kg ha-1 at flowering, respectively. The highest essential oil content was obtained at bolting (0.48 %), whereas the highest essential oil yield was obtained at flowering (17.9 kg ha-1). Z and E epoxy-ocimene was the main component in phenological periods, followed by β-myrcene and α-phellandrene. Chamazulene content varied between 6.48 to 8.84% at different phenological periods. The A. absinthium genotype may serve as an alternative source for Matricaria chamomilla L., which contains chamazulene levels between 2.3% to 10.9%. Very low thujone (α-Thujone between 0.24 and 1.07%, β-Thujone between 0.03 and 1.34%) was detected during the phenological periods. Even though A. absinthium had low essential oil content at the flowering period. In the study, harvesting at flowering time can be recommended as the most suitable time for agricultural production to achieve high plant, oil yields and high oil quality.
Under changing climate conditions, evaluating both genetic and environmental factors is essential for crop improvement. Limitations of conventional breeding have increased the use of molecular markers to obtain precise genotypic information and improve selection efficiency. This study evaluated drought tolerance in 15 durum wheat genotypes across two cropping seasons under rainfed and irrigated conditions. A randomized complete block design with four replications was used to assess agro-physiological traits, quality parameters, drought tolerance indices, and molecular diversity using iPBS and SCoT markers. Significant genotypic variation was observed for grain yield, 1000-kernel weight, hectoliter weight, protein and starch content, and color traits under both conditions. Ovidio had the highest grain yield and starch content, while Seckin 21 showed the highest 1000-kernel weight. Drought tolerance indices identified NZFM-41 and Maestrale as the most drought-resilient, and Ovidio as highly adaptable with stable yield. 12 indices (SSI, TOL, MP, GMP, STI, YI, YSI, HM, SDI, DI, RDI, SSPI) were calculated from yields under stress (Ys) and non-stress (Yp) conditions. Molecular analysis with 14 iPBS and 10 SCoT primers showed greater polymorphism and allelic diversity for iPBS (PIC = 0.287, Nei’s distance = 0.5348) than SCoT (PIC = 0.191, Nei’s distance = 0.2700). Clustering and population structure revealed two subpopulations, with iPBS providing higher resolution (FST = 0.3443). MP, GMP, STI, YI, HM, and DI were the most reliable indices for identifying drought-tolerant genotypes. In conclusion, iPBS markers exhibited higher discriminatory power than SCoT for assessing genetic diversity, while specific indices (MP, GMP, and STI) proved most effective for identifying drought-tolerant durum wheat genotypes, with NZFM-41 and Maestrale emerging as promising genetic resources for breeding programs aimed at enhancing climate resilience.
Seed treatments or coatings with micronutrients, beneficial microorganisms, or pesticides, along with the use of slow-release nitrogen fertilizers, have gained prominence in recent years for their ability to increase crop yield per unit area and reduce nitrogen losses from the soil. In this study, we investigated the effects of different nitrogen fertilizer forms and seed treatments on sunflower seed yield and quality in 2022 and 2023. Field experiments were conducted in a randomized complete block design with a split-plot layout and four replications. Four nitrogen fertilizer forms (NFF1: conventional form of ammonium sulfate; NFF2: conventional form of urea; NFF3: slow-release ammonium sulfate; and NFF4: slow-release urea) were applied to the main plots, while five seed treatments (ST0: no treatment (control); ST1: standard seed treatment (Metalaxyl-M + Oxathiapiprolin); ST2: standard seed treatment + micronutrients; ST3: standard seed treatment + potassium humate; and ST4: standard seed treatment + micronutrients + potassium humate) were applied to the sub-plots. Plant height, head diameter, seed yield, thousand-seed weight, crude oil content and crude oil yield were evaluated. The highest seed and crude oil yields were obtained from the NFF3 and NFF4 treatments in combination with the ST3 treatment.
The research examines the influence of year, sowing date, sweet corn genotype (Zea mays L. saccharata Sturt.), and irrigation norm on productive traits and sugar content in sweet corn kernels. The experiment was set up in a completely randomized block design with four replications. In both years, sowing was done in two periods: end of April - beginning of May and mid-July. Three hybrids (Enterprise, Union, and Sweet Nugget) were observed under three irrigation treatments: full norm (100%), reduced norm (50%) and natural wetting (control). Combined analysis of variance (pooled ANOVA) showed a statistically significant effect on all examined yield and sugar content parameters, as well as their higher-order interactions. Hybrid Enterprise stood out as the most productive, with the highest values of ear weight, kernel weight (up to 272.13 g) and kernel yield (up to 16.25 t ha-1 in the first year and up to 13.66 t ha-1 in the second year), especially in the second sowing date with full or reduced irrigation norm, with a shelling percentage over 70%. The highest content of total sugars (39.71% in the first year and 40.39% in the second year) was achieved in the Sweet Nugget hybrid in the first sowing date under natural moisture conditions, where a slight water deficit stimulates sugar concentration. The obtained results highlight the advantages of the Enterprise hybrid for high yield under irrigation conditions and the Sweet Nugget hybrid for kernel quality (sweetness), and underscore the importance of factor interactions.
Sorghum x sudangrass is an important forage crop in semi-arid regions due to its high biomass potential and efficient water use. Improving irrigation and nitrogen management is essential to sustain productivity under increasing water limitations. This study evaluated the effects of different irrigation levels and nitrogen doses on the growth, physiological responses, and forage traits of sorghum x sudangrass. Four irrigation levels (25, 50, 75, and 100% of full irrigation) and three nitrogen doses (50, 100, and 150 kg ha-1) were tested with three replications. Irrigation, nitrogen, and their interaction significantly affected plant performance. Plant height ranged from 227.3 cm under 25% irrigation with 50 kg N ha-1 to 313.6 cm under 75% irrigation with 100 kg N ha-1. Fresh forage yield varied between 23.5 and 66.7 t ha-1, while dry biomass ranged from 5.01 to 16.77 t ha-1. Physiological parameters responded positively to increasing inputs; the highest SPAD value (45.36) occurred at 75% irrigation with 100 kg N ha-1. LAI and NDVI reached their maximum under full irrigation with 100-150 kg N ha-1. Forage quality traits also responded to the treatments. ADF and NDF increased slightly with higher inputs, while crude protein yield ranged from 296 to 1191 kg ha-1. Overall, 75% irrigation combined with 100 kg N ha-1 produced yields and protein levels comparable to full irrigation with 150 kg N ha-1, indicating a more resource-efficient and sustainable management strategy. Incorporating drought-tolerant and resource-efficient forage species may further improve system resilience under Mediterranean water-limited conditions.
This study aimed to identify genomic regions associated with high-temperature stress tolerance in upland cotton, particularly during the vegetative period of this crop, which is increasingly affected by climate change. Understanding the genetic basis of thermotolerance is essential for improving resilience and sustaining yield under heat stress conditions. A total of 94 upland cotton genotypes were subjected to high-temperature stress in a low tunnel environment for four consecutive days during peak flowering. Physiological parameters, including relative cell injury (RCI), leaf temperature (LT), and SPAD chlorophyll values, were measured before and after the stress treatment to assess the genotypic response. Genotyping by sequencing (GBS) was used to detect single nucleotide polymorphisms (SNPs), and 6670 high-quality markers (MAF < 0.05) were retained for association mapping. Association analyses were conducted using general and mixed linear model (GLM-MLM) approaches. SNP markers associated with heat tolerance were identified using GLM and MLM models at significance levels of p < 0.0001-0.001 with a-Log10(P) threshold >= 2.5, and MLM results were validated using false discovery rate (FDR) correction. Four SNPs on chromosomes A07, A10, D03, and D09 (SNP1680, SNP2537, SNP4374, SNP6415) were linked to RCI; four SNPs on D05, D07, A10, and D08 (SNP5029, SNP5643, SNP2616, SNP5915) were associated with LT; and two SNPs on D12 and A08 (SNP7428, SNP1910) were related to SPAD chlorophyll content. These markers correspond to genomic regions encoding enzymes, proteins, and genes implicated in high-temperature stress responses in cotton (Gossypium hirsutum L.).
Plant nutrients are essential for plant physiology, although they are required in small quantities. Along with detecting nutrient shortages, it is crucial to study the varied impacts of nutrients such as iron, sulfur, and selenium. This study specifically investigated the combined effects of iron, sulfur, and selenium fertilizers on the oil content and oil quality factors of peanuts (Arachis hypogaea L.). The study was conducted in the Eastern Mediterranean of T & uuml;rkiye in 2021 and 2022, using a split-split-plot design with three replications. The treatments of Fe (0% and 3%) were assigned to the main plots, S (0, 40, and 60 kg ha-1) to the sub-plots, and Se (0, 20, and 40 ppm) to the sub-sub-plots. Oil content was not significantly affected by the fertilizer treatments, and the maximum values were obtained from the applications of 40 kg sulfur per hectare and 20 ppm selenium. Regarding the Oleic/Linoleic acids ratio, an important indicator of oil quality, the highest values were observed in the treatments of 40 to 60 kg sulfur per hectare and 20 to 40 ppm selenium. In conclusion, iron application had no significant effect, while the application of 40 to 60 kg ha-1 sulfur and 20 to 40 ppm selenium could improve the quality of peanut oil, as indicated by a low
Soil moisture has become increasingly crucial for sustaining winter crop yield potential under induced water scarcity resulted climate change. Durum wheat has strategic importance in Mediterranean agriculture, serving as both a staple food crop and a key economic commodity. This study aimed to evaluate the effects of supplemental irrigation in anthesis on yield performance, grain quality, technological traits, and health-related characteristics of durum wheat. A field experiment was conducted under irrigated and rainfed conditions with different growth habit durum wheat varieties during two growing seasons (2019/2020 and 2020/2021). Yield and its components, rheological and technological parameters, grain quality traits, total phenolic content, and antioxidant activity were assessed. Supplemental irrigation significantly enhanced grain yield, particularly under dry seasonal conditions, but slightly reduced technological quality, rheological properties, and antioxidant capacity. In contrast, rainfed conditions ensured the expression of desirable grain quality traits relevant to health, nutrition, and pasta end-use quality. Significant correlations were observed, with grain yield negatively associated with protein content (r = - 0.41**) and antioxidant activity (r = -0.49***), while protein content exhibited strong positive correlations with gluten index (r = 0.34**), fiber content (r = 0.70**), and antioxidant activity (r = 0.30*). These findings highlight the trade-off between yield and quality under contrasting water regimes. Overall, the results demonstrate that durum wheat exhibits high production potential in Mediterranean environments, with rainfed conditions enhancing quality attributes, thereby providing valuable insights for future breeding and agronomic strategies aimed at balancing yield stability with nutritional and technological quality.
Abiotic stresses triggered by climate change often damage peanut leaves (Arachis hypogaea L.) during developmental stages, and the effects of this damage on fat and fatty acids are unclear. Thus, this study examined the impact of leaf damage rates on the different growth stages of peanut (Arachis hypogaea L.) grown in the Eastern Mediterranean region of Osmaniye, T & uuml;rkiye, during the main crop season. The experiment was conducted in a split-split plot design with three replications during 2020 and 2021 vegetation periods. Different yield and quality criteria were studied by placing independent variables, such as varieties (NC 7 and Halisbey) on main plots, growth stages (R1, R2, and R3) on sub-plots, and leaf damage levels (control, 25%, 50%, and 75%) on sub-sub-plots. The highest oil content was obtained in the Halisbey (48.30%+/- 0.32) variety at the R3 stage (48.70%+/- 0.32) and at 75% leaf damage (48.27%+/- 0.21). The highest oleic acid was found in NC 7 variety (52.20%+/- 0.33), at the R3 stage (51.19%+/- 0.61), and %50 leaf damage (50.92%+/- 0.72). The order of leaf damage treatments in terms of linoleic acid was as follows: in control (49.95%+/- 0.31), in 75% leaf damage (50.37 +/- 0.60%), in 25% leaf damage (50.57%+/- 0.54), and in 50% leaf damage (50.92%+/- 0.72). As a consequence, it has been determined that the selection of varieties and integrated control against abiotic and biotic stresses are essential to reduce the effects of leaf damage on peanut fat and fatty acids.
This study was conducted to investigate the effects of silicon foliar application on the yield, photosynthetic pigments, biochemical traits, and antioxidant capacity of three Iranian safflower cultivars (Faraman, Goldasht, and Golmehr) under different moisture conditions during the 2019 and 2020 growing seasons in the hot and arid climate of Fars Province, Iran. The experiment was laid out as a factorial split-plot arrangement based on a randomized complete block design (RCBD) with three replications. The treatments included four irrigation regimes (full irrigation as control, irrigation withholding at stem elongation, flowering, and seed filling stages) assigned to the main plots, and the combination of three silicon concentrations (100, 150, and 200 mg L-1) with three safflower cultivars allocated to subplots. Results showed that the highest leaf area index (3.5) and chlorophyll a content (4 mg g(-1) fresh weight) were obtained under full irrigation (supplying 100% of the crop water requirement). In contrast, the highest proline content (5 mg g(-1) fresh weight) and peroxidase activity (1.55 U mg(-1) protein) were observed when irrigation was withheld during the flowering stage. Moreover, silicon application, particularly at 200 mg L-1, significantly enhanced photosynthetic pigments, biochemical compounds, and seed yield. Among the cultivars, Faraman exhibited superior levels of pigments, biochemical constituents, and antioxidant activity, as well as higher yield and greater drought tolerance than the others. Overall, flowering was identified as the most drought-sensitive growth stage in safflower, and silicon foliar application especially at 200 mg L-1 proved to be an effective approach for mitigating drought stress effects and improving yield.
Fusarium head blight (FHB) is the most devastating disease of small cereal grains worldwide caused by several Fusarium species. F. graminearum sensu stricto is the most frequently identified FHB pathogen within the F. graminearum species complex (FGSC). This pathogen produces the mycotoxin deoxynivalenol, which reduces grain quality and poses a threat to human and animal health. In this study, the effect of nitrogen (N) fertilizer rates (0, 50, and 100 kg N ha-1) on the incidence of Fusarium spp., levels of deoxynivalenol (DON), agronomic traits (plant height-PH, spike length-SL, and thousand-grain weight-TGW) and grain yield (GY) in two winter wheat cultivars (Nogal and NS Ilina) over two growing seasons (2016-2017 and 2017-2018) was investigated. Among Fusarium species, FGSC strains were the most frequently isolated in both years. The incidence of FGSC strains (20.22%), DON levels (323.59 mu g kg-1 1), PH (83.21 cm), TGW (38.68 g), and GY (8.88 t ha-1) were higher in 2017 than in 2018 (9.66%, 97.72 mu g kg-1, 71.05 cm, 34.35 g, and 5.11 t ha-1, respectively). Cultivar NS Ilina had significantly higher FGSC incidence (20.11%), DON levels (302 mu g kg-1), PH (85.57 cm), and SL (9.11 cm) than cultivar Nogal (9.77%, 104.71 mu g kg-1, 68.68 cm, and 7.65 cm, respectively). The N rate significantly increased PH, but did not affect the other investigated parameters. Although both wheat cultivars tested were susceptible to Fusarium pathogens and DON, Nogal displayed less susceptibility than NS Ilina. Therefore, adopting integrated disease management that focuses on FHB-resistant or less susceptible wheat cultivars can reduce the risk of pathogen presence and DON.
Potato is one of the most important plants in terms of yield potential, adaptability and nutritional content. Although potato breeding programs are integrated with many new technologies, they are intensively carried out by phenotypic observation and selection in field conditions. In the research, high dry matter content and PVY resistance were determined as the basic selection criteria in the development of new cultivars. The research was carried out between 2017-2022 using 30.000 F1 potato seeds as genetic material and by establishing comparative trials in different locations with commercial control cultivars. Selection and breeding studies were carried out considering PVY resistance according to the molecular marker test. As a result of the research, commercial candidate advanced lines suitable for PVY resistance, table, chip and French fry potato industries were developed by conducting phenotypic and genotypic selection and selection studies according to high dry matter content. Based on the findings of the present study, the lines 82-88-04, 82-45-24, 82-105-50, 82-78-16, 82-56-01, and 82-93-03, distinguished by their high yield potential and resistance to Potato virus Y (PVY), were identified as possessing significant potential for official registration and subsequent commercialization as candidate cultivars.
This research was conducted to determine the parents and hybrids with superior general and specific combining ability in 20 F-1 hybrids, including five female lines and four male testers. In the study, five advanced lines were used as female parents and four registered varieties were used as male parents to cross, resulting in 20 F-1 hybrids according to line x tester mating design during the 2021-2022 growing season. The 20 crosses and nine parents were evaluated in a randomized complete block design with three replications during 2022-2023 growing season. The results showed that the BC10 and BC22 lines had the highest general combining ability in terms of seed yield, while the Awassa tester had the highest general combining ability in terms of pod number per plant and seed yield. However, BC10 x Saryan, BC13 x Awassa and BC21 x Awassa hybrid combinations showed the highest specific combining ability in seed yield. It was stated that both additive and non-additive gene effects were efficacious for yield and several key yield components in the hybrid progenies. The promising hybrid combinations BC10 x Saryan (48.72**), BC21 x Awassa (126.74**) and BC13 x Awassa (127.83**) exhibited positive significant heterosis for seed yield.
Confronting the challenges of climate change, population expansion, and food security in Bangladesh demands the development of high-yielding, resilient rice varieties adapted to various agro-ecological zones. This study aimed to identify superior rice genotypes with consistent performance during the dry season (November-May) under irrigated condition using multi-environment trials (METs) at ten locations. Seven genotypes, along with a control variety, were evaluated for grain yield and agronomic parameters, including plant height, growth duration, panicle number, filled spikelets per panicle, and thousand-grain weight (TGW). The genotype-by-environment interaction (GEI) was analyzed, and stability was assessed using Weighted Average of Absolute Scores with Yield (WAASBY) and Multi-Trait Stability Index (MTSI) metrics. Results revealed significant GEI effects, with genotype BR(Bio)9777-116-12-2-5 demonstrating the highest yield and stability across environments. Grain yield showed strong positive correlations with most traits except TGW. WAASBY analysis identified BR(Bio)9777-116-12-2-5 as top-performing and stable genotypes, whereas others, such as BR(Bio)9777-84-4-1-1 and BR(Bio)9777-123-4-6-1 were less productive and unstable. MTSI further confirmed the exceptional performance of BR(Bio)9777-116-12-2-5, highlighting its suitability for varied agro-ecological zones. These outcomes underscore the significance of combining yield and stability metrics in breeding programs providing a valuable framework for developing climate-resilient rice varieties to enhance productivity and ensure food security in Bangladesh. This research offers valuable guidance for addressing emerging agricultural challenges and promoting sustainable food systems in the face of global environmental and population pressures.
Legumes are sensitive to drought stress, which adversely affects their seed yield, protein and oil content. This was investigated in a two-year field experiment conducted using a split-plot design with three replications in the Mughan plain, Ardabil. The experimental factors included drought stress as the main plot at three levels (60, 100, and 140 mm of evaporation from a class A pan) and the co-inoculation of soybean symbiotic bacteria and arbuscular mycorrhizal fungus species across eight treatments (Bradyrhizobium japonicum, Funneliformis mosseae, Rhizophagus irregularis, Glomus fasciculatum, B. japonicum + F. mosseae, B. japonicum + R. irregularis, B. japonicum + G. fasciculatum, and control) as the subplot. The results revealed that heightened drought stress led to a reduction in plant dry weight, pod number, seed number per plant, and seed yield in all treatments in both study years. However, this reduction was less pronounced in some treatments, especially those involving co-inoculation with B. japonicum + R. irregularis and B. japonicum + G. fasciculatum. Conversely, all treatments exhibited an increase in stomatal resistance, chlorophyll a concentration, soluble sugars, malondialdehyde (MDA), peroxidase (POD), and superoxide dismutase (SOD) under drought conditions (100 and 140 mm) compared to the normal irrigation conditions (I60). The saturated fatty acids (palmitic and stearic acids) declined in inoculated plants compared to the control, while the trend was the opposite for unsaturated fatty acids (linoleic, linoneic, and oleic acids). Drought stress increased palmitic acid content by up to 32.4% and reduced linolenic acid content by up to 13.4%. Among the treatments, co-inoculation with B. japonicum + R. irregularis and B. japonicum + G. fasciculatum demonstrated a more significant improvement in the soybean's drought tolerance compared to the others. Given these results, inoculating soybean plants with rhizobial bacteria and R. irregularis mycorrhizae can be recommended as a strategy to enhance their drought resistance and improve their seed yield and oil quality.
