ارزیابی توانایی کانی‌های سپیولیت و پالیگورسکیت در فراهم نمودن منیزیم گیاه سورگوم با مایه زنی قارچ میکوریزی گلوموس موسه Glomus mosae))

نوع مقاله: کاربردی

نویسندگان

1 دانشجوی کارشناسی ارشد گروه خاکشناسی دانشکده کشاورزی دانشگاه شهید چمران اهواز

2 دانشیار گروه خاکشناسی، دانشگاه شهید چمران اهواز، اهواز، ایران.

3 استاد گروه خاکشناسی، دانشگاه شهید چمران اهواز، اهواز، ایران.

4 استادیار گروه خاکشناسی، دانشگاه شهید چمران اهواز، اهواز، ایران.

چکیده

سپیولیت و پالیگورسکیت از گروه رس­های فیبری هستند که در خاک­های مناطق خشک و نیمه خشک یافت می­شوند. شناخت در زمینه رفتار این دو کانی­ در محیط ریزوسفر گیاهان کشاورزی و کارکرد ریزجانداران اندک است. این پژوهش با هدف بررسی مقدار رهاسازی منیزیم از دو کانی سپیولیت و پالیگورسکیت، در ریزوسفر گیاه سورگوم در شرایط همزیست با قارچ میکوریزی گلوموس موسه به گونه آزمایش فاکتوریل در قالب طرح کاملاً تصادفی با سه تکرار انجام شد. فاکتورهای آزمایشی شامل منبع منیزیم در سه سطح (محلول غذایی، پالیگورسکیت و سپیولیت) و قارچ در دو سطح (وجود و عدم وجود قارچ) بودند. گیاه سورگوم در گلدان­های دارای شن کوارتزی و نیز سپیولیت یا پالیگورسکیت سترون شده پس از اعمال تیمارهای قارچی کشت و با محلول غذایی جانسون دارای منیزیم و بدون منیزیم در دوره کشت 70 روزه تغذیه شدند. پس از پایان دوره کشت، در آغاز کلروفیل گیاهان، بلندی گیاه و قطرساقه به­ترتیب با کلروفیل متر، متر نواری و کولیس اندازه­گیری شدند. سپس ریشه­ها و اندام هوایی از یکدیگر جدا شده و بیومس گیاه، درصد کلونیزاسیون ریشه­ها و اندازه منیزیم جذب شده گیاه پس از آسیاب و عصاره­گیری، بررسی گردید. بیشترین درصد کلونیزاسیون ریشه در تیمارهای دارای پالیگورسکیت و کم­ترین اندازه آن در تیمار شاهد بوده است؛ ولی اندازه منیزیم جذب شده گیاه و شاخص کلروفیل در تیمارهای حاوی کانی پالیگورسکیت به­طور قابل توجهی کم­تر از سایر تیمارها بوده است. مقایسه شرایط حضور و عدم حضور قارچ گلوموس­موسه نشان داد که در حضور قارچ اندازه منیزیم جذب شده گیاه سورگوم از این دو کانی بیش­تر بوده است؛ لذا می­توان اظهار داشت که حضور قارچ گلوموس­موسه به­صورت همزیست با گیاه سورگوم تأثیر معنی­داری بر رهاسازی منیزیم از کانی سپیولیت و پالیگورسکیت و جذب آن توسط گیاه داشته است و در این ارتباط رهاسازی منیزیم از کانی سپیولیت به­طور قابل توجهی بیش­تر از پالیگورسکیت بود.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Evaluation of palygorskite and sepiolite abilities to supply Mg for sorghum plants in presence/absence of Glomus mosae mycorhizae

نویسندگان [English]

  • Faranak Ghasemi 1
  • ُSaeid Hojati 2
  • Ahmad Landi 3
  • Roya Zalaghi 4
1 M.Sc student, Department of Soil Science, College of Agriculture, Shahid Chamran University of Ahvaz
2 Associate Professor, Department of Soil Science, Faculty of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
3 Professor, Department of Soil Science, Faculty of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
4 Assistant Professor, Department of Soil Science, Faculty of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
چکیده [English]

Introduction Clay minerals are considered as the main source of ion exchange and storage of nutrients in the soil. Knowledge of change and transformation of minerals, in relation to plant nutrition, fixation and release of elements is important. Sepiolite and palygorskite are fibrous clay minerals widely distributed in arid and semi-arid soils. Both minerals are rich in Mg and therefore, their weathering can significantly affect the chemistry of Mg in soil. Biological weathering which is carried out by living organisms (i.e. plant roots, soil fungi and bacteria) plays an important role in providing nutrients to plants. Hence, the use of microorganisms such as mycorrhizal fungi in the rhizosphere of agricultural crops has become more widespread. In recent years several studies have been conducted in relation to the weathering of minerals in the rhizosphere soil. However, few studies in terms of mycorhizal symbiosis with plant roots were carried out on release of Mg from sepiolite and palygorskite. Therefore, a pot experiment with a factorial arrangement through a completely randomized design was conducted to identify how symbiosis of sorghum roots with Glomus mosae mycorhizae affects release of Mg from sepiolite and palygorskite. 
Materials and Methods Pots containing sterile quartz sand and sepiolite or palygorskite (25-53 µm) were prepared and fungal treatments including presence or absence of fungus Glomus mosae were applied to the pots and then sorghum seeds were sown. Johnson nutrient solutions containing magnesium and without magnesium were used to feed plants during 70 days of experiment. After harvesting, the chlorophyll content, plants height and stem diameter were measured by SPAD, tape measure and caliper, respectively. Afterwards, the roots and shoots were separated and plants biomass and the percentage of roots colonization determined. Then, plants were oven-dried, ground, and the magnesium contents of them after extraction with 1M hydrochloric acid were determined using Agilent 7000 ICP analyzer. The chemical composition of palygorskite, sepiolite, and quartz sand was determined using X-ray fluorescence (XRF) and their mineralogical composition was determined using X-ray diffraction (XRD) approach.
Results and Discussion Analysis of variance for the main effect of treatments on plant height, stem diameter, shoot dry weight and root dry weight showed that the effect of different sources of magnesium on plant height, stem diameter and shoot dry weight was significant (P < 0.01). The highest and lowest height, stem diameter, root and shoot dry matter were found in treatments fed with complete Johnson solutions and the palygorskite, respectively. The results also illustrated that application of Glomus mosae symbiotic mycorhizae significantly increased plant height, stem diameter, and root and shoot dry matter compared with non-mycorhizal treatments. This could be attributed to the fact that Mycorrhizal fungi (Glomus mosae) absorb more water and nutrients through increased photosynthesis and plant growth, consequently leading to improved plant characteristics when compared with non-mycorhizal crops. The results also showed the highest percentage of root colonization in palygorskite treatments and the lowest one in control. In general, a symbiotic relationship is created to improve low nutrition of elements that the amount of them in the soilwith a little mobility. Therefore, anything that exacerbates this deficiency, leads to an increase in symbiosis between plants and fungi. On the other hand, When plant is faced with more nutrient deficiencies, the demand for a symbiothic fungusGlomus mosae increases. Besides, the greatest magnesium concentration and chlorophyll contents were found in control, sepiolite and palygorskite treatments, respectively. In all treatments, magnesium intake was sufficient to grow sorghum, but as the results show, the amount of magnesium in the control and that of sepiolite was much more than palygorskite. These results clearly show that sepiolite mineral is able to release more Mg than palygorskite. The results also showed that the presence of the fungus Glomus mosae has significantly affected the release of Mg from both minerals.
Conclusion In both sepiolite and palygorskite treatments, magnesium and chlorophyll content increased in symbiosis with fungi. This shows the positive effect of Glomus mosae fungus on release of Mg from these two minerals, especially sepiolite.  Although, both sepiolite and palygorskite were able to provide enough amounts of Mg for sorghum plants, however, it seems that in long-term Mg released from sepiolite can more easily meet the need of plants when compared with palygorskite.

کلیدواژه‌ها [English]

  • Sepiolite
  • Palygorskite
  • Symbiosis
  • Glomus mosae
  • Mg