اثر سویه‌های bacillus pumilus و zhihengliuella halotolerans بر صفات مورفو-فیزیولوژیک گیاه قره‌داغ (nitraria schoberi) تحت تنش گرد و غبار

در این پژوهش تاثیر باکتری‌های محرک رشد گیاه bacillus pumilus و zhihengliuella halotolerans بر صفات مورفو-فیزیولوژیک گیاه قره‌داغ تحت تاثیر گرد و غبار (شاهد و 1/5 میلی‌گرم بر متر مربع در ماه) مورد بررسی قرار گرفت. نتایج نشان داد که گرد و غبار بر صفات مورفولوژیک و فیزیولوژیک گیاه تاثیر منفی دارد. گرد و غبار باعث کاهش 20، 15، 17 و 20 درصدی در به‌ترتیب کلروفیل a، کاروتنوئید، پروتئین محلول کل و زیست‌توده خشک و افزایش فلاونوئید کل، محتوای فنل کل، ظرفیت آنتی‌اکسیدانی کل و گلایسین‌ بتائین به‌ترتیب به مقدار 107، 32، 15 و 10 درصدی در مقایسه با نمونه شاهد شد. هر دو باکتری شرایط گیاه را در برابر تنش بهبود بخشیدند؛ به‌طوری‌که b. pumilus و z. halotolerans به‌ترتیب باعث افزایش مقدار 13 و 21 درصدی کلروفیل b،و27 و 43 درصدی پروتئین، 60 و 27 درصدی زیست‌توده خشک در شرایط شاهد گرد و غبار شد. در این میان نقش سویه b. pumilus بیش‌تر از سویه z. halotolerans بود؛ به‌طوری‌که سویه b. pumilus به‌تنهایی بیش‌ترین تاثیر را در افزایش معنی‌دار کلروفیل a و شاخص کیفیت نهال به‌ترتیب به مقدار 52 و 108 درصد در تیمار گرد و غبار داشت. نتایج این پژوهش نشان داد که باکتری‌های محرک رشد گیاه جداسازی‌شده از گیاهان مرتعی شور‌پسند می‌توانند باعث افزایش مقاومت گیاه قره‌داغ در شرایط تنش گرد و غبار شوند. این موضوع در جنگل‌کاری بهینه این‌گونه و تثبیت ریزگرد‌های نمکی در پلایاها (دریاچه‌های خشک) در اکوسیستم‌های خشک و نیمه‌خشک دارای اهمیت است.

the potential of plant growth-promoting rhizobacteria bacillus pumilus and zhihengliuella halotolerans strains on the morpho-physiological traits of nitraria schoberi under dust stress

in this research, the effect of plant growth-promoting rhizobacteria, bacillus pumilus, and zhihengliuella halotolerans, on the morpho-physiological traits of nitraria schoberi under the influence of dust (control and 1.5 g/m^2/month) was investigated. the results showed that dust had a negative effect on the morphological and physiological traits of the plant. dust caused a decrease of 20, 15, 17 and 20% in chlorophyll a, carotenoid, total soluble protein, and total dry biomass and an increase in the total flavonoids, total phenol content, total antioxidant capacity and glycine betaine amounting to 107, 32, 15 and 10 percents, respectively. both bacteria improved the condition of the plant against stress, so that b. pumilus and z. halotolerans increased the amount of chlorophyll b by 13 and 21%, protein by 27 and 43%, and total biomass by 60 and 27%, respectively. in this experiment, the role of b. pumilus strain was more than that of z. halotolerans strain, so that b. pumilus strain alone had the greatest effect in increasing chlorophyll a and seedling quality index by 52 and 108%, respectively. the results showed that b. pumilus and z. halotolerans strains can increase the resistance of the nitraria schoberi to dust stress and help us to stabilize salty dusts in playas. background and objective: salt and dust can cause harmful effects on the photosynthetic activity and serious damage to the plant. plants under these stresses will experience a series of morphological, physiological and biochemical changes (4). in recent years, the use of plant growth-promoting rhizobacteria as a leading strategy in reducing the effects of environmental stresses has attracted the attention of researchers (3). in this research, the effect of inoculation of two bacteria, bacillus pumilus and zhihengliuella halotolerans, on some morphological and physiological traits of nitraria schoberi under dust stress was investigated. the results of this research can help us in the optimal afforestation of this species under dust in the conditions of climate change in arid and semi-arid ecosystems. methods: three-month old seedlings of the same size were inoculated by plant growth-promoting bacteria under dust stress in a two-factor factorial experiment with a randomized complete block design in three replications in a period of 5 months. the strains of bacillus pumilus and zhihengliuella halotolerans were provided by previously purified research by amini et al. (2022) (1). inoculation was applied twice to the plant roots. only nutrient broth solution without bacteria was applied to the control plants. dusting was done using a simulator. the amount of falling dust equal to 1.5 grams per square meter per month was applied once a week. after completing the treatments, 8-month old seedlings were sampled for physiological and morphological tests. the amounts of chlorophyll a, b and leaf carotenoid, total anthocyanin and flavonoid, total phenol content, total antioxidant activity, glycine betaine, malondialdehyde and total soluble protein were measured (2). results: the results showed that dust had a negative effect on the morphological and physiological traits of the plant. dust caused a decrease of 20, 15, 17 and 20% in chlorophyll a, carotenoid, total soluble protein, and total dry biomass and an increase in total flavonoid, total phenol content, total antioxidant capacity and glycine betaine amounting to 107, 32, 15 and 10 percents, respectively. both bacteria improved the condition of the plant against stress, so that b. pumilus and z. halotolerans increased the amount of chlorophyll b by 13 and 21%, protein by 27 and 43%, and total biomass by 60 and 27%, respectively. in this experiment, the role of b. pumilus strain was more pronounced than that of z. halotolerans strain. b. pumilus strain alone had the greatest effect in increasing chlorophyll a and seedling quality index by