مؤسسه انتشارات دانشگاه تهران علوم گیاهان زراعی ایران 2008-4811 57 1 2026 03 21 The Effect of Growth-Promoting Bacteria and Salicylic Acid on Some Biochemical Indices of Common Bean Genotypes under Drought Stress تأثیر باکتری‌ محرک رشد و اسیدسالیسیلیک بر برخی شاخص‌های بیوشیمیایی ژنوتیپ‌های لوبیای معمولی (.Phaseolus vulgaris L) تحت تنش خشکی 119 138 105735 10.22059/ijfcs.2025.397019.655149 FA نرگس اسدیان گروه زراعت و اصلاح نباتات، دانشکدگان کشاورزی و منابع طبیعی، دانشگاه تهران، کرج، ایران علی احمدی گروه زراعت و اصلاح نباتات، دانشکدگان کشاورزی و منابع طبیعی، دانشگاه تهران، کرج، ایران. منیژه سبکدست نودهی گروه زراعت و اصلاح نباتات، دانشکدگان کشاورزی و منابع طبیعی، دانشگاه تهران، کرج، ایران. 0000-0002-0403-2208 Journal Article 2025 06 21 Introduction. With an average annual rainfall of 240 mm, Iran is classified as an arid country, and more than 40% of its agricultural lands face water shortages. Drought is one of the most important abiotic stresses and a major factor limiting crop yield in arid and semi-arid regions. Common bean (Phaseolus vulgaris L.), as one of the most important sources of plant protein, is highly sensitive to water deficit, with yield reductions of up to 87% having been reported. Among the main defense mechanisms of plants against drought stress are the accumulation of osmolytes, enhancement of soluble proteins, and activation of antioxidant enzymes. In this context, salicylic acid plays a crucial role in drought tolerance by regulating photosynthesis, enhancing the antioxidant system, and reducing oxidative damage, while rhizosphere growth-promoting bacteria such as Rhizobium contribute to improved plant adaptation to drought through nitrogen fixation and the production of plant growth hormones. Recent studies have shown that the combined application of salicylic acid and plant growth-promoting bacteria can have synergistic effects in improving membrane stability, increasing antioxidant activity, and mitigating the damage caused by stress. Materials and Methods. The present study was conducted as a field experiment during the 2021–2022 growing season at the research farm of the University of Tehran (Karaj), on a clay loam soil, using a split-factorial arrangement in a randomized complete block design with three replications. The treatments included three irrigation levels (100, 60, and 30% of field capacity), two levels of salicylic acid (0 and 0.5 mM), two levels of Rhizobium (non-inoculation and inoculation with strain R160), and two bean genotypes (Sadri, drought-tolerant, and Yas, drought-sensitive). Seeds were inoculated with Rhizobium before sowing, and foliar application of salicylic acid was carried out at two stages (15 and 30 days after seedling emergence). Drought stress was imposed one month after sowing, and leaf sampling was performed two weeks later from the third fully expanded leaf. Biochemical and physiological traits, including electrolyte leakage, protein content, proline, malondialdehyde, and the activities of antioxidant enzymes (CAT, POD, APX, GR) were measured according to standard methods. Data were analyzed using SAS 9.4 software, and mean comparisons were conducted with the LSD test at the 5% probability level. In this study, two common bean (Phaseolus vulgaris L.) genotypes (Sadri and Yas) were evaluated under drought stress and treatments with salicylic acid and Rhizobium bacteria. Biochemical and physiological parameters, including protein content, proline, malondialdehyde, activities of catalase, peroxidase, ascorbate peroxidase, glutathione reductase, and electrolyte leakage, were investigated. Results and Discussion. The results showed that drought stress significantly affected all traits, while hormone and bacterial treatments improved biochemical status and reduced cellular damage. Proline accumulation, as an indicator of osmotic adjustment, increased with the severity of drought stress; however, the combined application of salicylic acid and Rhizobium reduced its content, indicating a regulatory role of these treatments in alleviating oxidative stress and protecting cells. Under stress conditions, especially at severe levels, the Sadri genotype exhibited higher proline content than the Yas genotype. These findings, consistent with previous studies, highlight the crucial role of proline accumulation and osmotic adjustment in drought tolerance. Drought stress also increased malondialdehyde content and electrolyte leakage, which are indicators of membrane damage and oxidative stress, while salicylic acid and Rhizobium treatments reduced these parameters, reflecting their protective effects on membrane integrity and plant water balance. These protective effects were more evident in the drought-tolerant Sadri genotype, confirming the role of these factors in enhancing drought tolerance. Antioxidant enzyme activities, including catalase, peroxidase, ascorbate peroxidase, and glutathione reductase, increased with drought intensity, and hormone and bacterial treatments further enhanced these activities. The increase in antioxidant enzyme activities reduced the accumulation of reactive oxygen species and protected cellular structures, indicating the reinforcement of the plant defense system under water deficit. Conclusion. Overall, the findings suggest that these physiological and biochemical traits can serve as key indicators for evaluating drought tolerance in different common bean genotypes. The novelty of this research lies in the simultaneous evaluation of salicylic acid and Rhizobium bacteria under normal irrigation and drought stress conditions in two bean cultivars with different levels of drought tolerance. This treatment combination has been rarely addressed in previous studies and provides an opportunity for a more precise explanation of the physiological and biochemical mechanisms associated with stress tolerance. The findings revealed that the combined application of salicylic acid and Rhizobium enhanced and strengthened the antioxidant system. These results highlight the great potential of integrating hormonal and microbial factors in the sustainable management of drought stress and the development of eco-friendly strategies to improve the production of beans and other crops. تنش خشکی یکی از مهم‌ترین تنش‌های غیرزیستی محسوب می‌شود که تولید محصولات زراعی و حبوبات را در سراسر جهان تهدید می‌کند. هدف پژوهش حاضر، بررسی برخی صفات فیزیولوژیکی و بیوشیمیایی در لوبیای معمولی تحت شرایط تنش خشکی بود. برای این منظور، آزمایشی در مزرعه تحقیقاتی گروه زراعت دانشکدگان کشاورزی و منابع طبیعی دانشگاه تهران واقع در کرج، طی سال زراعی ۱۴۰1، به‌صورت آزمایش اسپلیتفاکتوریل در قالب طرح کامل تصادفی با سه تکرار اجرا شد. تیمارهای این طرح شامل سه سطح آبیاری (آبیاری نرمال و آبیاری بر اساس ۳۰ و ۶۰ درصد ظرفیت زراعی)، دو سطح هورمون سالیسیلیکاسید (صفر و 5/0 میلی‌مولار سالیسیلیکاسید)، دو سطح باکتری (عدم استفاده و استفاده از باکتری ریزوبیوم تثبیت‌کننده نیتروژن Rhizobium leguminosarum biovar phaseoliسویه R160) و دو ژنوتیپ لوبیا (صدری و یاس) بود. نتایج نشان داد که افزایش شدت تنش خشکی موجب کاهش محتوای پروتئین و افزایش میزان پرولین، مالوندی‌آلدئید، نشت الکترولیت، کاتالاز، پراکسیداز، آسکورباتپراکسیداز و گلوتاتیونپراکسیداز شد. همچنین، کاربرد سالیسیلیکاسید و باکتری ریزوبیوم نسبت به شاهد (عدم استفاده از هورمون و باکتری)، باعث بهبود محتوای پروتئین و فعالیت‌های آنزیمی شد و در عین حال میزان مالون‌دی‌آلدئید و نشت الکترولیت را کاهش داد. رقم حساس و متحمل نیز در صفات نشت الکترولیت، محتوای پروتئین و مالوندیآلدئید تفاوت معنیداری با هم داشتند. بهطور کلی، این نتایج ایده استفاده توأم از سالیسیلیکاسید و باکتری ریزوبیوم را بهعنوان روشی مؤثر برای افزایش تحمل به خشکی در ارقام حساس و متحمل لوبیای معمولی تقویت می‌کند.

https://ijfcs.ut.ac.ir/article_105735_878321163a9be6dcefb367925e738f4e.pdf