تأثیر باکتری های ریزوبیوم بر غلظت K، Ca و Na گیاه گندم (Triticum aestivum L.) در خاک های شور

نوع مقاله : علمی - پژوهشی

نویسندگان

دانشگاه فردوسی مشهد

چکیده

شوری خاک یکی از مشکلات مهم در تولید فرآورده های کشاورزی است و سطح نسبتاً گسترده ای از زمین های کشاورزی در دنیا و ایران با مشکل شوری روبه رو هستند. یکی از اثرات شوری خاک، بروز اختلال در تغذیه گیاهان است و معمولاً مقادیر زیاد کلرید سدیم در محیط ریشه، سبب کاهش جذب، انتقال و تجمع یون هایی مانند پتاسیم و کلسیم در گیاه می شود. این پژوهش به منظور بررسی تأثیر تعدادی از جدایه های باکتری ریزوبیوم بر غلظت عناصر K، Ca، Na و نسبت K/Na گیاه گندم (Triticum aestivum L.) در خاک هایی با شوری مختلف، در شرایط گلخانه-ای در سال 89-1388 انجام شد. آزمایش در قالب طرح کاملاً تصادفی با آرایش فاکتوریل با چهار سطح باکتری (سینوریزوبیوم ملیلوتی، بردی-ریزوبیوم ژاپونیـکوم و ریزوبیوم لگـومینوزاروم و شـاهد) و سه سطـح شوری خـاک (دو، شش و ده دسی زیمنس بر متر) در سه تکرار انجام شد. نتایج این پژوهش نشان داد که با افزایش شوری خاک، وزن خشک ریشه و شاخساره، غلظت عناصر K، Ca و همین طور نسبت K/Na کاهش معنی دار نسبت به شاهد داشت. باکتری سینوریزوبیوم ملیلوتی در شوری دو دسی زیمنس بر متر و باکتری ریزوبیوم لگومینوزاروم در شوری های شش و ده دسی زیمنس بر متر بیشترین وزن خشک شاخساره (به ترتیب 4/19 و 7/13 درصد افزایش نسبت به شاهد)، غلظت های K، Ca و کمترین غلظت Na در گیاه گندم را ایجاد کردند.

کلیدواژه‌ها


عنوان مقاله [English]

Effects of rhizobial bacteria on K, Ca and Na concentration of wheat (Triticum aestivum L.) in saline soils

نویسندگان [English]

  • S homayoon
  • A lakzian
  • Gh Haghnia
  • R Khorasani
چکیده [English]

Introduction
Soil salinity is one of the major agricultural problems and it is limiting crop productivity in many parts of the cultivated areas all over the world. Saline soils are differentiated by the presence of great ratios of Na/Ca, Na/K, Ca2+, Mg2+, and Cl/NO3 (Gratan & Catherine, 1993) and high levels of neutral salts in the surface layers, which are resulting from the capillary action (Al-Falih, 2002). Osmotic stress occurs when soluble salts increase in the soils and then results in specific ion toxicity (Agarwal & Ahmad, 2010). Therefore, one of the most important side effects of salinity is nutritional disorders. High concentration of NaCl in the root medium usually reduces nutrients uptake and affects the transportation of potassium and calcium ions in plant. (Gratan & Catherine, 1993) reported that the salinity of soils changes ionic strength of the substrate and it can influence mineral nutrient uptake and translocation. Salinity also changes the mineral nutrient availability and disrupts the mineral relations of plants. Hence, the main purpose of this research is to evaluate the effects of rhizobial bacteria inoculation on K, Ca and Na concentration of wheat (Triticum aestivum L.) in saline soils.

Material and methods
Soil sample was collected from Astan Ghodse Razavi farm, Mashhad Iran, and then was dried and passed through a 12-mesh (approximately 2 mm) screen. Soil sample was divided into three parts and then was placed into three containers. Each container was watered by a different proportion of saline water (EC= 10 dS.m-1). Salinity of soils was regularly monitored until three salinities (2, 6 and 10 dS.m-1) came out. Then, a completely randomized design with a factorial arrangement was carried out in a greenhouse condition. The experimental factors included four levels of inoculation (Sinorhizobium meliloti, Bradyrhizobium japonicum and Rhizobium leguminosarum and control) and three levels of soil salinity (2, 6 and 10 dS.m-1) with three replications. Wheat seeds were sterilized in 5% sodium hypochlorite for 2-3 minutes and were washed several times and then were germinated and seedlings were inoculated with bacterial strains. Inoculated wheat seedlings were grown in 1 kg pots. Wheat seedling was watered with sterilized water for one month and was harvested for chemical analysis. Potassium and sodium concentrations in plant tissues were determined by flame photometer and calcium concentration was measured by using Atomic absorption spectroscopy (AAS).

Results and discussion
The results showed that the root and shoot dried weight, K and Ca concentrations and K/Na ratio in wheat shoot were significantly decreased with increasing soil salinity. The lowest shoot and root dry weight were observed in high level of salinity (10 dS.m-1). Inoculation of wheat seedlings with rhizobial bacteria had a positive effect on shoot and root dry weight. The highest shoot and root dry weight were obtained when wheat seedlings were inoculated with Sinorhizobium meliloti in non-saline soil treatment (2 dS.m-1). Calcium concentration increased significantly in all levels of salinity when wheat seedlings were inoculated with Rhizobium leguminosarum. Among all tested strains, Rhizobium leguminosarum had a prominent effect on growth of wheat seedlings. With increasing soil salinity, the concentration of sodium increased in shoot and root tissues and K/Na ratio declined dramatically. The lowest K/Na ratio was found in the highest level of salinity (10 dS.m-1). On contrast, the K/Na ratio in wheat shoot was amplified when wheat seedlings were inoculated with rhizobial strains. The highest K/Na ratio was observed in Rhizobium leguminosarum treatment. There are data that show that wheat cultivars having greater leaf K:Na, K ion flux, and growth improve under saline conditions (Mayak et al., 2004; Morant Manceau et al., 2004; Yao, 2010). It seems that Rhizobium leguminosarum reduced the detrimental effect of salinity to some extent.

Acknowledgements
This research was partially supported by vice president for research and technology of Ferdowsi University of Mashhad. We thank our colleagues who provided insight and expertise that greatly assisted the research, although they may not agree with all of the interpretations or conclusions of this paper.

References
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کلیدواژه‌ها [English]

  • Bacterial inoculation
  • K/Na ratio
  • Salt tolerance
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