تاثیر کاربرد برگی کلسیم و تلقیح با قارچ اندوفیت serendipita indica بر بهبود رشد، رنگیزه‌های فتوسنتزی و افزایش ظرفیت آنتی‌اکسیدانی انگور بی‌دانه سفید تحت تنش خشکی

میزان تولید و کیفیت محصولات کشاورزی تا حد زیادی تحت تاثیر تنش‌های غیر‌زیستی مانند خشکی است. این پژوهش با هدف بررسی اثر کاربرد کلسیم و قارچ serendipita indica بر رشد و تغییرات مورفوفیزیولوژیکی انگور بی‌دانه سفید تحت تنش خشکی انجام شد. آزمایش به‌صورت فاکتوریل در قالب طرح‌کاملا‌تصادفی با دو سطح کاربرد برگی نیترات‌کلسیم (صفر ‌و ‌یک‌درصد)، دو سطح قارچ s. indica (تلقیح و عدم تلقیح) و سه سطح تنش خشکی (0.2-مگاپاسکال به‌عنوان شاهد، 0.7- و 1.2- مگاپاسکال) و با چهار تکرار اجرا شد. صفات مورد بررسی در این آزمایش شامل نسبت وزن خشک به سطح برگ (lma)، محتوای‌‌نسبی آب برگ (rwc)، پایداری غشای سلولی(msi)، رنگیزه‌های فتوسنتزی (کلروفیل ‌و‌کاروتنوئیدها)، میزان مالون‌دی‌آلدئید (mda)، قندهای محلول، فنول، میزان فعالیت آنزیم‌های آنتی‌اکسیدان، پروتئین محلول و اسیدآمینه‌ی پرولین بود. نتایج نشان داد سطوح خشکی، قارچ و کلسیم و اثرات متقابل دو جانبه و سه جانبه آنها، اثرات معنی‌داری بر صفات اندازه‌گیری ‌شده داشت. با افزایش سطح تنش، میزان کربوهیدرات‌های محلول، محتوای مالون‌دی‌آلدئید، پرولین، فنول و فعالیت آنزیم‌های آنتی‌اکسیدان (کاتالاز، پراکسیداز و سوپراکسیددیسموتاز) افزایش ‌و پایداری غشاء‌سلولی (msi)، محتوای ‌نسبی ‌آب ‌برگ (rwc)، پروتئین‌های محلول، محتوای کلروفیل و کاروتنوئیدها و نسبت وزن‌خشک‌ به ‌سطح برگ (lma) کاهش یافت. تلقیح ریشه نهال‌های انگور ‌با ‌قارچ s. indica، کاربرد برگی نیترات‌کلسیم‌ و برهمکنش آنها با بهبود صفات مورفوفیزیولوژیکی اثر مثبتی برکاهش اثرات تنش خشکی نشان داد. بنابراین، به نظر می‌رسد استفاده بهینه از عناصر در کنار کاربرد قارچ‌های اندوفیت می‌تواند به عنوان یک راهکار مناسب برای افزایش مقاومت انگور به تنش خشکی در نظر گرفته شود.

effect of foliar application of calcium and inoculation with endophytic fungus, serendipita indica, on improving growth, photosynthetic pigments, and increasing antioxidant capacity of ‘sultana’ grapevine (vitis vinifera) under drought stress

this research investigated the effect of calcium application and serendipita indica (varma et al., 1999) inoculation on the growth and morphophysiological parameters of grapes under drought stress. a completely randomized design was applied with two levels of foliar application of calcium (0 and 1%), two types of fungal inoculation (non-inoculated and s. indica), and three levels of drought stress (0.2 mpa as control, -0.7, and -1.2 mpa) with four replications. the traits include leaf mass per area (lma), relative water content (rwc), cell membrane stability, photosynthetic pigments, malondialdehyde, soluble sugars, phenol contents, antioxidant enzyme activity, soluble protein, and proline. according to the results, the levels of drought, fungus, and calcium, as well as their interactions, had a significant effect on physiological traits. with an increase in the level of stress, the amount of soluble carbohydrates, the content of malondialdehyde, proline, phenol, and the activity of antioxidant enzymes (catalase, peroxidase, superoxide dismutase, and guaiacol peroxidase) increased, while the stability of the cell membrane, rwc, soluble proteins, photosynthetic pigments, and the ratio of lma decreased. root inoculation of grape seedlings with s. indica fungus, foliar application of calcium nitrate, and their interaction showed a positive effect in alleviating drought stress. therefore, it seems that the optimal use of elements and endophytic fungi can be considered a suitable strategy to increase the resistance of grapes to drought stress. introduction biological methods that utilize beneficial soil organisms and horticultural practices such as applying nutrients play a significant role in enhancing resistance to abiotic stresses. the endophytic fungus, serendipita indica has attracted attention due to its growth-promoting mycorrhizal-like functions, broader host range compared to mycorrhizal fungi, and the ability to be cultured in artificial media (varma et al., 1999). this fungus has been successfully utilized in promoting growth and improving resistance to abiotic stresses in different plants (karimi et al., 2022; ghabooli & kaboosi, 2022). considering the water scarcity challenge in iran and its significant impact on reducing agricultural products, and considering the importance of grapevine plants, studying and developing strategies to mitigate the negative effects of drought stress in grapevine plants is of paramount importance. this research aimed to investigate the potential impact of calcium application along with root colonization by the endophytic fungus s. indica on drought stress tolerance in grapevine (vitis vinifera l. cv sultana) plants. materials and methodsthis research was conducted as a factorial experiment in a completely randomized design with four replications. it aimed to evaluate the effects of calcium foliar application and inoculation with the endophytic fungus, s. indica on growth and morphophysiological parameters in grapevine plants under drought stress conditions. the experimental treatments included two levels of calcium (0% and 1%), two fungal treatments (inoculated and non-inoculated), and three stress levels (0.2 mpa as control, 0.7 mpa, and 1.2 mpa as second and third drought stress levels, respectively). grape cuttings were rooted in a suitable rooting medium. for inoculation, a suspension of fungal mycelia (1% w/v) was prepared and the cuttings were placed in the suspension for one hour and then transplanted into pots. the other group of cuttings (control) was immersed in water for one hour. calcium nitrate foliar application was performed at two levels of 0% and 1%. after 10 days of inoculation, root samples were harvested to assess root colonization. drought stress treatments were applied at the 15th or 16th leaf stage and were applied when the soil water potential reached the desired value. after two weeks, sampling was done and traits such as relative water content, photosynthetic pigments, soluble carbohydrates, protein, proline, malondialdehyde, and antioxidant enzymes were measured. results and discussionthe results showed that drought stress, fungus, calcium, and their interactions had a significant effect on the measured traits. drought stress increased the levels of carbohydrates, malondialdehyde, proline, phenols, and antioxidant enzymes, while decreasing membrane stability, relative water content, protein, chlorophyll, and carotenoids. inoculation with the fungus, calcium application, and their interactions had a positive effect on reducing the effects of stress by improving morphophysiological traits. several mechanisms have been proposed for the positive effect of the fungus on increasing growth, including increased cytokinin production and improved transport through the vascular system. fungal mycelia increase the absorption surface and thus help to retain water around the plant (ghabooli & kaboosi, 2022). calcium also plays a role in maintaining membrane structure and function and increases the water retention capacity of cells (albino-garduno et al., 2008). the fungus increases the levels of carbohydrates, proteins, and proline through certain hexose transporters, affects plant hormone synthesis, and increases the expression of some genes involved in protein and proline synthesis (ghabooli et al., 2013). calcium increases carbohydrate accumulation by interfering with the photosynthesis process and acts as a secondary messenger to affect protein stability and activity. besides, calcium can reduce membrane damage by maintaining and enhancing the activity of antioxidant enzymes and increasing proline accumulation (hosseini tafreshi et al., 2019). the effect of the fungus on reducing ros production is one of the reasons why membrane stability is higher in inoculated plants under stress conditions (kaboosi et al., 2023b). the fungus and calcium might play an important role in eliminating reactive oxygen species by increasing the activity of antioxidant enzymes, which is consistent with their effect on carotenoid levels, membrane stability, and malondialdehyde content. this demonstrates that these plants reduce the detrimental effects of drought stress more than control plants. conclusionthe results showed that inoculation with s. indica with grapevine plants and treatment with calcium effectively stimulated the growth and resistance to drought stress. under drought stress, they were able to play an effective role in improving the physiological traits of the plant, which in turn improved the plant’s tolerance to drought stress. in sum, the results indicate that using calcium-containing fertilizers and utilizing beneficial microorganisms such as endophytic fungi can be considered a suitable strategy to increase the growth and yield of grapes and achieve sustainable agriculture in the production of this product.