ارزيابي اثر دوگونه‌ ميكوريزا و كود زيستي نيتروكسين بر عملكرد و اجزاي عملكرد سير (Allium sativum L.) در يك نظام زراعي اكولوژيك

Evaluation of Two Mycorrhiza Species and Nitroxin on Yield and Yield Components of Garlic (Allium sativum L.) in an Ecological Agroecosystem

در سال‌های اخیر همواره استفاده از نهاده‌های بیولوژیك به‌عنوان یكی از راهكارهای اساسی در جهت توسعه پایدار محصولات زراعی و به‌ویژه گیاهان دارویی مطرح بوده‌اند. به‌منظور بررسی اثر گونه‌های مختلف میكوریزا و كود زیستی نیتروكسین بر عملكرد و اجزای عملكرد سیر آزمایشی در سال زراعی 89-1388 در مزرعۀ تحقیقاتی دانشكدۀ كشاورزی دانشگاه فردوسی مشهد، به‌صورت فاكتوریل در قالب طرح پایۀ بلوك‌های كامل تصادفی و با سه تكرار انجام شد. عوامل مورد بررسی شامل گونه‌های مختلف میكوریزا (Glomus mosseae، Glomus intraradices و شاهد بدون میكوریزا) و كود زیستی (كاربرد و عدم كاربرد نیتروكسین (دارای باكتری‌های Azotobacter sp. و Azospirillum sp.)) بودند. نتایج آزمایش نشان داد كه تلقیح با دو گونه میكوریزا صفات مورد مطالعه را نسبت به شاهد افزایش دادند. وزن سوخ در بوته به‌طور معنی‌داری تحت‌تأثیر گونه‌های مختلف میكوریزا قرار گرفت، به‌طوری‌كه گونه‌های Glomus mosseae و Glomus intraradices وزن سوخ در بوته را به‌ترتیب 48 و 29 درصد نسبت به شاهد افزایش دادند. تلقیح با نیتروكسین به‌طور معنی‌داری بر طول و قطر سوخك تأثیر داشت، به‌طوری‌كه به‌ترتیب باعث افزایش 13 و 8 درصدی طول و قطر سوخك نسبت به شاهد شد. با توجه به نتایج آزمایش، تلقیح با Glomus mosseae در تلقیح و عدم‌تلقیح با نیتروكسین، در اكثر صفات مورد مطالعه نسبت به سایر تیمارها برتر بود. اثر متقابل تلقیح نیتروكسین و گونه‌های مختلف میكوریزا بر تمامی صفات مورد مطالعه معنی‌دار بود. نیتروكسین اثر تمامی گونه‌های میكوریزای مورد مطالعه را در مقایسه با شرایطی كه این میكوریزاها به تنهایی به‌كار رفتند تشدید كرد. بیشترین (4306 كیلوگرم در هكتار) و كمترین (1665 كیلوگرم در هكتار) عملكرد اقتصادی به‌ترتیب در تیمارهای تلقیح Glomus mosseae توأم با تلقیح نیتروكسین و عدم میكوریزا + عدم تلقیح نیتروكسین به‌دست آمد. به‌طور كلی با توجه به یافته‌های این پژوهش، به نظر می‌رسد می‌توان با استفاده از نهاده‌های بیولوژیك ضمن كاهش مصرف كودهای شیمیایی و مخاطرات زیست‌محیطی ناشی از آنها، پایداری تولید را در درازمدت حفظ نمود.

Introduction Maintenance of soil fertility is one of the most important issues affecting the sustainability of food production. The application of ecological inputs such as mycorrhiza and biofertilizers are one of those approaches which are needed to maintain soil fertility Biofetilizers include different types of free living organisms that convert unavailable nutrients to available forms and enhance root development and better seed germination. Plant growth promoting rhizobacteria (PGPR) occupy the rhizosphere of many plant species and have beneficial effects on the host plant. They may directly and indirectly influence the plant growth. A direct mechanism would be to increase plant growth by supplying the plant with nutrients and hormones. Indirect mechanisms, on the other hand, include reduced susceptibility to diseases and acting as a form of defense referred to as induces systematic resistance. Mycorrhiza arbuscular fungi are other coexist microorganisms that improve soil fertility, nutrients cycling and agroecosystem health. Mycorrhizal fungi are the most abundant organisms in agricultural soils. Many researchers have pointed to the positive roles of mycorrhizal fungi on plants growth characteristics. Arbuscular mycorrhizas are found in 85% of all plant families and occur in many crop species. Mineral nutrients such as potassium, calcium, copper, zinc and iron are assimilated more quickly and in greater amounts by mycorrhizal plants. Arbuscular mycorrhizal inoculation has also been shown to increase plant resistance of pathogen attack. Garlic (Allium sativum L.) is a very powerful medicinal plant that is often underestimated. Garlic is easy to grow and can be grown year-round in any mild climates. Garlic cloves are used for consumption (row and cooked) or for medicinal purposes. They have a characteristic pungent, spicy flavor that mellows and sweetens considerably with cooking. Despite of many studies on the effects of mycorrhiza and biofertilizers on different crops, information on the effects of these factors for many medicinal plants such as garlic is scarce; therefore, in this study the effects of mycorrhiza and biofertilizers on quantitative characteristics of garlic in a low input cropping system were studied. Materials and Methods In order to study the effects of two mycorrhiza species and nitroxin on yield and yield components of garlic (Allium sativum L.), an experiment was conducted in a factorial arrangement based on a randomized completed block design with three replications in the growing seasons of 2010 at the experimental farm of College of Agriculture, Ferdowsi University of Mashhad, Iran. The experimental factors were all combination of two mycorrhiza species (Glomus mosseae, Glomus intraradices) and control and also inoculation with and without nitroxin (include Azotobacter sp. and Azospirillum sp.) as a biofertilizer. Results and Discussion The results showed that both two mycorrhiza species had superior effects on most of the study traits compared with control. Bulb weight per plant was significantly affected by mycorrhiza species. Glomus mosseae، and Glomus intraradices increased bulb weight per plant by 48 and 29 percent compared with control, respectively. Nitroxin had a significant effect on length and diameter of bulbs. Length and diameter of bulbs were increased by 13 and 8 percent using nitroxin compared with control, respectively. Interactive effects of mycorrhiza and nitroxin on all study traits also were significant. Interactive effects of study treatments showed that Glomus mosseae had better effect on most of study traits at with and without nitroxin treatments. On the other hand, nitroxin had synergistic effect on mycorrhiza treatments compared when these treatments were used without nitroxin. Highest (4306 kg ha-1) and lowest (1665 kg ha-1) economic yield (bulb yield) were obtained from Glomus mosseae + Nitroxin and control (without mycorhiza and nitroxin), respectively. In general, results revealed that using biological inputs may decrease chemical fertilizers application and their environmental effects, and will increase sustainablity of crop production in long term. It seems that different species of mycorrhiza improved quantitative characteristics of garlic due to provide better conditions to absorption and transportation of nutrient to the plant. It has been reported that this ecological input provides favorable conditions for plant growth and development through improvement of physical, chemical and biological properties of the soil. It can be concluded that improvement of most of study traits in the present study were due to use of mycorrhiza and biofertilizers. Acknowledgements This research (grant number 18/P., 11 March 2010) was funded by Vice Chancellor of Research of the Ferdowsi University of Mashhad, which is hereby acknowledged.