ارزيابي و انتخاب توده‌هاي متحمل به تنش خشكي شنبليله (Trigonella foenum-graecum) بومي ايران در مرحله جـوانه‌زني و رشد گيـاهچه

Evaluation and Selection for Drought Tolerance in Iranian Fenugreek (Trigonella foenum-graecum) Landraces at Germination and Seedling Growth Stages

این بررسی به منظور ارزیابی واكنش توده‌های بومی شنبلیله كشور در برابر تنش خشكی القایی بوسیله پلی‌اتیلن‌گلیكول 6000 بر روی بیست توده بومی در قالب آزمایش فاكتوریل و بر پایه طرح بلوك‌های كامل تصادفی با سه تكرار در شرایط آزمایشگاهی انجام شد. سطوح تنش شامل پتانسیل‌های صفر(آب دی یونیزه)، 2- ، 4- ، 6- و 8- بار بود. نتایج نشان داد كه سطوح مختلف تنش خشكی بر روی تمامی صفات مورد بررسی(درصد بذرهای جوانه‌زده، طول ریشه‌چه، طول ساقه‌چه، نسبت طول ساقه‌چه بر ریشه‌چه، وزن‌تر ریشه اولیه، وزن‌تر ساقه‌چه، نسبت وزن تر ساقه‌چه به ریشه‌چه، وزن خشك ریشه‌چه و سـاقه‌چه ) اثرات معنی‌داری داشت. بین توده‌های بومی به غیر از صفت وزن خشك ریشه اولیه، در كلیه صفات مورد مطالعه اختلاف معنی‌داری مشاهده شد. بر اساس روش رتبه‌بندی میانگین هفت صفت اصلی مورد مطالعه در این پژوهش(درصد جوانه‌زنی، طول ریشه‌چه و ساقه‌چه، وزن تر و خشك ریشه‌چه و ساقه‌چه)، توده‌های بومی كاشان و نیشابور متحمل‌ترین و توده‌های بومی ری و خاش حساس‌ترین توده‌ها در برابر تنش خشكی در مرحله جوانه‌زنی و رشد گیاهچه بودند. با در نظر گرفتن نتایج این بررسی، توجه به توده‌های بومی شنبلیله كشور و بهره‌برداری از قابلیت‌های نهفته در آنها از قبیل تحمل و مقاومت به تنش‌ خشكی و محافظت از آنها به عنوان منابع با ارزش ژنتیكی توصیه می‌شود.

Introduction: Fenugreek (Trigonella foneum-graecum L.) has been cultivated in vegetable farms at the most parts of Iran. It is an annual crop belonging to the Leguminosae family. It originated from west Asia and Iran and cultivated at mostly in European, Asian and African countries, presently. With distinguished of feeding and medicinal values, low needs to soil conditions and its width adaptability to cultivation in different regions, the range of fenugreek cultivation areas have been extended from America to India. In most parts of Iran there is limiting possibilities for cultivation of horticultural and agricultural crops for the reason of limiting water harvesting and unsuitable rainfall distributions. There is no doubt that introduction of new crops for such conditions could increase variation of crops production and stability of farming systems. Plants landraces have been created in thousands of cultivation years under different climatologically and local cropping systems. They are evolved by natural and artificial selection under environmental conditions where they were grown and there have accumulative adaptive genes for tolerance to biotic and abiotic stresses and are the most precious materials in starting of breeding programs. Germination phase is the most important period that guaranties the growth and establishments of crops. One of the basic activators of germination starters is water and limiting of it (drought) is the most important retardant of seed growth during germination period under field condition. Fast germination and emergence of seedling from soil and high preliminary growth rate has been known for one of the drought escape mechanisms for most crops such as chickpea, lentil and bean. In breeding programs of crops, using in vitro method is one of the most used methods in germplasm selection for drought tolerance. This study carried out under laboratory condition in order to evaluate some Iranian fenugreek landraces reactions to drought stress. Materials and Methods: In order to evaluate the Iranian fenugreek landraces reactions to drought stress induced by Poly Ethylene Glycol 6000, twenty fenugreek landraces originated from different parts of Iran were used in this study. The experiment was conducted at Maragheh experimental station of the Dry land Agricultural Research Institute (DARI) under laboratory condition, with a factorial experiment based on randomized complete blocks design and three replications. The stress levels were zero (di-ionized water),-2, -4,-6 and -8 bar. Fifteen normal and health seeds from each landraces were cultivated in petridishes and stayed under fixed temperature (25±1 degree of centigrade), 12 hour day/night for fourteen days. Seedling characteristics (seed germination percentage, root and stem lengths, ratio of stem length to root length, root and stem fresh weights, ratio of stem fresh weight to root fresh weight, root and stem dry weights) were noted. Data were analyzed by MSTAT-C software and comparisons of noted traits means done by Duncan’s Multiple Range Test at 5% probability level. In order to distinguish tolerant and susceptible genotypes, landraces ranked by using of Sarmadnia et al.,(1988) and Kafi et al.(2005) methods, and with using of the main traits such as seed germination percentage, root and stem lengths, root and stem fresh weights, root and stem dry weights. Results and Discussion: Results showed that, drought stress levels had significantly affected on all study traits (seed germination percentage, root and stem lengths, ratio of stem length to root length, root and stem fresh weights, ratio of stem fresh weight to root fresh weight, root and stem dry weights). The differences among landraces were highly significant in all traits except in primary root dry weight. The most visible differences among the genotypes in germination percentage monitored at less than -4 bars. Based on ranking of genotypes with seven main studied traits (seed germination percentage, root and stem lengths, root and stem fresh weights, root and stem dry weights), Kashan and Neyshaboor were the most tolerant and Rey and Khash were the most susceptible landraces among the studied genotypes at germination and seedling growth stages. Conclusion: It could be concluded that, there are differences among the Iranian fenugreek landraces in case of reaction to drought stress at germination and seedling growth stages that shows suitable diversity among them. Moreover, using from less than -4 bar drought stress levels recommended for screening and selection of drought tolerance fenugreek genotypes. Also, it is recommended attention to Iranian fenugreek landraces and using the hidden potentials of them same as drought tolerance and resistance. It is suggested protection of them as a precious genetically resources in gene bank.