بررسی اثرات تنش اسمزی و سمیت یونی ناشی از شوری با استفاده از پاسخ های سریع فتوسنتزی گندم دوروم

نوع مقاله : مقاله پژوهشی

نویسندگان

1 استادیار، دانشکده کشاورزی، دانشگاه شهید چمران اهواز

2 استاد، مؤسسۀ تحقیقات علمی و صنعتی کشورهای مشترک‌المنافع (CSIRO)، کنبرا، استرالیا

چکیده

شوری رشد گیاه را از طریق تنش اسمزی ناشی از وجود نمک در محیط اطراف ریشه و نیز سمیّت یونی ناشی از تجمع نمک در برگ­ها تحت تأثیر قرار می­دهد. ارزیابی ویژگی­های فتوسنتزی به عنوان روشی سریع و غیرتخریبی، توان بالایی برای بهبود بهره‌وری گیاه و تحمل به تنش دارد. به­منظور بررسی اثرات تنش اسمزی کوتاه‌مدت (45 دقیقه) بر ویژگی­های فتوسنتزی، چهار رقم­ گندم دوروم (به نام‌های کولتر، سکلاوی، کاندیکنز، برکولیا) با تحمل شوری متفاوت، در غلظت­های پایین 50 میلی­مولار کلریدسدیم و کلریدپتاسیم در آزمایشی گلدانی ارزیابی شدند. تبادلات گازی و به دنبال آن فتوسنتز بلافاصله با آغاز تنش اسمزی ناشی از هر دو تیمار (بهترتیب به میزان 10-15 و 3-5 درصد) کاهش یافتند، اگرچه با گذشت زمان میزان آنها تا حدودی ترمیم یافت. ویژگی­های فتوسنتزی بهطور مشابه به غلظت­های ایزواسمزی کلریدسدیم و کلریدپتاسیم پاسخ دادند. ارتباط بین غلظت سدیم برگ و پاسخ هدایت روزنه­ای هر چهار رقم، 45 دقیقه پس از رویارویی با هر دو نوع نمک نشان داد که هیچ تأثیر ویژه­‌ای از حضور سدیم در گیاه وجود ندارد. در مجموع به نظر می­رسد مهم­ترین عامل ایجاد پاسخ­های فتوسنتزی در استفاده از مواد اسمزی مختلف، در واقع فشاراسمزی ناشی از تنش در فضای اطراف ریشه‌ بوده است نه اینکه اثرات یونی ناشی از سمیّت سدیم باشد.

کلیدواژه‌ها


عنوان مقاله [English]

Osmotic stress and ion-toxicity effects of salt stress using immediate photosynthetic responses of durum wheat

نویسندگان [English]

  • Afrasyab Rahnama 1
  • Rana Munns 2
  • Richard James 2
1 Assistant Professor, University of Ahvaz, Iran
2 Professors, Australia
چکیده [English]

Salinity affects plant growth by the osmotic stress of salt around the roots as well as by toxicity caused by excessive accumulation of salt in leaves. The study of photosynthetic traits as a rapid and non-destructive tool demonstrates the great potential for improving plant productivity and stress tolerance. A pot experiment was carried out to investigate short-term effects of osmotic stress (45 min) on photosynthetic traits of four durum wheat genotypes (namely Coulter and Seklavi, Candicans and Brkulja) differing in salt tolerance under low concentrations of 50 mM KCl and NaCl. Gas exchange and photosynthesis were reduced immediately after the onset of osmotic stress caused by both treatment (10-15% and 5-10%, respectively), but were recovered immediately over the time. Photosynthetic traits responded similarly to iso-osmotic concentrations of KCl and NaCl. The relationship between Na+ concentration in the leaf and stomatal conductance response in all four genotypes exposed to both salt treatments for 45 min showed no effect of Na+ toxicity within the plant. Stomatal factors limit photosynthesis of salt-stressed plants more than non-stomatal components of photosynthesis. In general, it seems that the main factor affecting of photosynthetic responses using diferrent osmotic was osmotic pressure of the salt outside the roots not the Na+ toxicity.

کلیدواژه‌ها [English]

  • Net photosynthesis
  • Osmotic stress
  • Stomatal conductance
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