اثر تلقيح گونه‌هاي قارچ ميكوريز (AMF) بر رشد و مواد مؤثره نعناع فلفلي (Mentha piperita)

The Role of Mycorrhizal Inoculation on Growth and Essential Oil of Peppermint (Mentha piperita)

استفاده از پتانسیل میكروبی خاك از جمله قارچ¬های میكوریز آربوسكولار (AMF)برای بهبود رشد و تغذیه گیاه بطور گسترده¬ای مورد توجه قرار گرفته است. این مطالعه به منظور بررسی تأثیر قارچ¬های میكوریز آربوسكولار بر رشد و درصد مواد مؤثره نعناع فلفلی تحت شرایط گلخانه¬ای در قالب طرح كاملاً تصادفی با 4 تیمار قارچ میكوریز آربوسكولار انجام شد. تیمارهای تلقیحی شامل 1) شرایط بدون تلقیح (C)، 2) گلوموس فسیكولاتوم (Gf)، 3) گلوموس اینترارادیسز (Gi) و 4) گلوموس موسه (Gm) بودند. در پایان دوره رشد برخی پارامترهای رشدی شامل ارتفاع، قطر ساقه، تعداد شاخه جانبی، تعداد برگ، وزن تر و خشك برگ و همچنین درصد مواد مؤثره و درصد كلنیزاسیون ریشه نعناع فلفلی اندازه¬گیری شدند. نتایج نشان داد تلقیح با قارچ¬های میكوریز آربوسكولار اثر معنی داری (05/0P≤)، بر روی پارامترهای اندازه¬گیری داشته است. تلقیح با قارچ¬های میكوریز آربوسكولار، ارتفاع گیاه، قطر ساقه، تعداد شاخه¬های جانبی، تعداد برگ، ماده تر و خشك برگ، درصد كلونیزاسیون ریشه و محتوی (25 درصد) و عملكرد اسانس (28 درصد) را افزایش داد. منتول، منتون و 1و 8-سینئول بالاترین فراوانی را در مواد موثره نعناع تشكیل دادند. تأثیر قارچ-های میكوریز آربوسكولار بر وزن خشك ریشه و درصد كلونیزاسیون ریشه معنی¬دار (05/0P≤) بود. بیشترین و كمترین درصد كلونیزاسیون ریشه (به ترتیب 47 و 0 درصد) در گیاهان تلقیح شده با Gf و تیمار شاهد مشاهده گردید.

Introduction: Arbuscular mycorrhizal symbiosis is formed by approximately 80% of the vascular plant species in all terrestrial biomes. Using soil microbial potential including arbuscular mycorrhizal fungi (AMF) has been widely considered for improving plant growth, yield and nutrition. Medicinal herbs are known as sources of phyto chemicals or active compounds that are widely sought worldwide for their natural properties. Members of the Lamiaceae family have been used since ancient times as sources of spices and flavorings and for their pharmaceutical properties. Peppermint (Mentha piperita) has a long tradition of medicinal use, with archaeological evidence placing its use at least as far back as ten thousand years ago. Essential oils - are volatile, lipophilic mixtures of secondary plant compounds, mostly consisting of monoterpenes, sesquiterpenes and phenylproponoids.Arbuscularmycorrhizal fungi with colonizing plant roots improve nutrient uptake as well as improving essential oil yield of medicinal plants by increasing plant biomass. The aim of the present study was to evaluate the effect of AMF inoculation on essential oil content and some growth parameters of peppermint (Mentha piperita) plant under glasshouse condition. Materials and Methods: This study was performed on a loamy sand soil. The samples were air-dried, sieved ( <5 mm) and thoroughly mixed. Some soil physicochemical properties were measured and then sterilized in 1 atm and 121°C for 2 h -. The pot experiment was carried out in a completely randomized design with four AMF treatments (1) control or no inoculation (C) 2) Glomus fasciculatum (Gf), 3) Glomus intraradices (Gi), 4) Glomus mosseae (Gm)and five replicates. -:. Rhizomes of peppermint were planted into a hole in a substrate where the inoculum had been previously added. Plants were kept in a glasshouse with a 16/8 h light and dark photoperiod, 26/22±2°C day and night temperatures, respectively. After 120 days of growth, at the end of the vegetative period some growth parameters including plant height, stem diameter, the number of lateral branches, leaf number, leaf fresh and dry weight and root colonization percentage of peppermint were measured. At full flowering stage, essential oil content was evaluated in the aerial parts of the plants as well as percentage and yield of essential oils were determined. Characteristics of essential oils analyzed by gas chromatography The components of the oil were identified by comparison of their mass spectra with those of a computer library or with authentic compounds and confirmed by comparison of their retention indices either with those of authentic compounds or with data published in the literature. Results and Discussion Results showed significant effects of AMF inoculation (P ≤0.05) on study parameters. Inoculation with AMF increased plant height, stem diameter, the number of lateral branches, leaf number, leaf fresh and dry weight, essential oil content (25 %) and final yield (28%). Effects of three AMF inoculations on Ocimum basilicum development differed from the Glomus species (Glomus intraradices, Glomus fasciculatum and Glomu smosseae). Overall, Glomus fasciculatum showed high efficiency as compared toG. mosseae and G. intraradices. Maximum shoot fresh and dry weights were obtained in plants treated with Glomus fasciculatum inoculation, followed by Glomus intraradices, Glomus mosseae and control (no inoculation). Effect of AMF inoculation on root colonization percentage was significant (P ≤0/05). The highest and the lowest values of root colonization percentage (47 and 0 %) were –observed in plants inoculated with Gf and control, respectively. Essential oil content in inoculated plants was significantly higher than other treatments. The plants inoculated with AMF showed an improvement of oil composition. Menth one and isomenth one were higher in inoculated plants compared with control ones. These results demonstrated that AMF concomitantly increases essential oil production and biomass in peppermint which is rich in commercially valued essential oils. Fungal symbiotic associations have the potential to enhance root absorption area, and stimulate the acquisition of plant nutrients including metal ions. Mycorrhizal roots have been known to absorb phosphorus (P) faster than non-mycorrhizal plants. An increase in nutrient uptake especially P could have resulted from ameliorating of nutrients stress and an increase in photosynthetic rates, which could ultimately increase the host plant growth. Conclusion: It is concluded that AMF inoculation in particular Glomusfasciculatum- with high efficiency of root colonization increasedthe photosynthetic pigments, nutrient uptake and plant relative water content which led to improved -bothyield of essential oils and nutrient contents.