ارزیابی ژنوتیپ‌های گلرنگ بهاره با استفاده از شاخص‌های تحمل و حساسیت به تنش گرمای آخر فصل

به منظور مقایسه ارقام بهاره گلرنگ (carthamus tinctorius l.) با استفاده از شاخص‌های تحمل و حساسیت به تنش گرمای آخر فصل در اهواز، آزمایشی در مزرعه پژوهشی دانشگاه کشاورزی و منابع طبیعی رامین خوزستان در سال زراعی 96-1395 به صورت کرت‌های یک بار خرد شده در قالب بلوک‌های کامل تصادفی با چهار تکرار انجام شد. فاکتورهای آزمایشی شامل چهار تاریخ کاشت (20 آبان، 11 آذر، 15 دی و 14 بهمن) در کرت های اصلی و پنج رقم گلرنگ (سینا، گلدشت، صفه، محلی اصفهان (کوسه) و فرامان) بود. نتایج نشان داد که ارقام مورد مقایسه از نظر صفت عملکرد دانه از لحاظ شاخص‌های حساسیت به تنش (ssi)، شاخص تحمل (ti)، میانگین بهره‌وری (mp)، میانگین هارمونیک (hm)، شاخص پایداری عملکرد (ysi)، میانگین هندسی (gmp)، شاخص تحمل تنش (sti)، شاخص خسارت تنش (sdi)، شاخص تحمل تنش تعدیل شده برای شرایط مناسب (msti1)، شاخص تحمل تنش تعدیل شده برای شرایط نامناسب (msti2) و شاخص درصد کاهش عملکرد (yri) تفاوت معنی‌داری داشتند. با این حال اختلاف ارقام مورد بررسی از نظر شاخص رتبه بندی (ri) و شاخص عملکرد (yi) معنی دار نبود. در شاخص تحمل تنش (sti)، رقم گلدشت (0.335) بیشترین تحمل (کمترین حساسیت) و رقم محلی اصفهان (کوسه) با میانگین (0.157) کمترین تحمل (بیشترین حساسیت) نسبت به تنش گرمای آخر فصل خوزستان را داشتند. به طور کلی شاخص تحمل تنش (sti) نسبت به سایر شاخص‌های مورد بررسی، جهت شناسایی ارقام متحمل و حساس گلرنگ نسبت به تنش گرمای آخر فصل در خوزستان مناسب است.

Evaluation of spring safflower genotypes by using tolerance and sensitivity indices to terminal heat stress

Introduction To plant breeding in relation to high temperature tolerance, and for determining the differences between resistant genotypes, several indices in the basis of crop yield in normal and stressed conditions were be introduced. With regard to importance of genetic breeding for higher yield and stability in exposure to terminal heat stress in warm region of Iran, and little studies about tolerance of safflower cultivars, this study was carried out by measuring tolerance and sensitivity indices. Safflower is one the most important oil crops in regions that have dry and warm winters like to Khuzestan province of Iran. This crop are relatively tolerant to environmental stresses. But it is reported there are significant differences between different cultivars. The study was conducted to evaluate the difference between safflower cultivars in Ahvaz region. Materials and Methods To comparison of safflower cultivars by indices of tolerance and sensitivity to terminal heat stress, present study was carried out in Ramin Agriculture and Natural Resources University of Khuzestan, at 20162017. A split plot design in the basis of Randomized Complete Blocks Design (RCBD) with four replications was used for the study. Experimental factors was included four sowing date (11 November, 2 December, 5 January and 3 February) were placed in main plots, and safflower cultivars (sina, goldasht, soffeh, Esfahan local (kooseh) and faraman) were placed in subplots. In this study, several indices with regard to researcher’s reports were calculated and used for determining the difference between safflower cultivars. Statistical analysis was done using by SAS v. 9.1 software. Results and Discussion The results of statistical analysis showed that investigated cultivars had significant differences in terms of Stress Sensitivity index (SSI), Tolerance Index (TI), Productivity Mean (PM), Harmonic Mean (HM), Yield Stability Index (YSI), (GPM), Stress Tolerance Index (STI), Stress Damage Index (SDI), and Modified Stress Tolerance for appropriate conditions (MSTI1), Modified Stress Tolerance for no appropriate conditions (MSTI2), and Yield Reduction Index (YRI). However, differences between cultivars in terms of Ranking Index (RI) and Yield Index (YI) were not significant. Therefore, STI was the best index for evaluating tolerance and sensitivity of safflower cultivars to terminal heat. On the basis of STI, most tolerate and sensitive cultivars were goldasht and Esfahan local (kooseh), respectively. Conclusion The results showed that safflower cultivars had significant differences in terms of tolerance indices calculated in the study. In the basis of Stress Tolerance Index (STI), goldasht cultivar had highest tolerance (lowest sensitivity) and local Esfahan cultivar (kooseh) had lowest tolerance (highest sensitivity) to terminal heat stress. Generally, in regions exposed to environmental stress, best cultivars are the cultivars that in normal conditions have high yield and in stressed conditions have no significant reduction f yield (groupA in Fernandez classification). In this study, stress tolerance index (STI) had good ability for determining of these cultivars. Key words: Comparison, cultivar, grain yield, sowing date, stress tolerance index