بررسی تنوع ژنوتیپ‌های عدس (lens culinaris medik.) تحت تنش یخ‌زدگی در شرایط کنترل‌شده

این مطالعه به‌منظور بررسی صفات موثر در تحمل به یخ‌زدگی ژنوتیپ‌‌های عدس، به‌صورت فاکتوریل در قالب طرح کاملاً تصادفی با سه تکرار در شرایط کنترل‌شده در دانشگاه فردوسی مشهد در سال 1398 اجرا شد. عوامل موردمطالعه شامل 18 ژنوتیپ عدس در چهار دمای یخ‌زدگی (صفر، 15-، 18- و 20- درجه سانتی‌گراد) بودند. نتایج نشان داد که کاهش دما به 18- و 20- درجه سانتی‌گراد سبب کاهش درصد بقاء در بیشتر ژنوتیپ‌ها شد. بیشترین درصد بقاء در دمای 18- درجه سانتی‌گراد در ژنوتیپ mlc11 مشاهده شد. هیچ‌کدام از ژنوتیپ‌های موردمطالعه قادر به تحمل دمای 20-درجه سانتی‌گراد نبودند. در دمای 15- درجه سانتی‌گراد ژنوتیپ‌های mlc13، mlc17، mlc70، mlc409 و mlc454 دارای بقای بالای 80 درصد بودند. تجزیه به عامل‌ها نشان داد که عامل اول 31.12 درصد از تغییرات را با کلروفیلa، کاروتنوئیدها، نسبت cha/chb، کل رنگ‌دانه‌های فتوسنتزی و مهار فعالیت رادیکال آزاد dpph و عامل دوم 18.28 درصد از تغییرات را با کلروفیلb، پراکسیداز، ارتفاع بوته و زیست‌توده توجیه می‌کند. با توجه به این صفات ژنوتیپ‌های mlc8، mlc13، mlc17، mlc38، mlc84، mlc286 و mlc334 به‌عنوان ژنوتیپ‌های با تحمل بالا به تنش می‌باشند. تجزیه خوشه‌ای ژنوتیپ‌ها و مقایسه میانگین گروه‌ها نشان داد که تمامی صفات به‌جز کربوهیدرات‌های محلول، پرولین، محتوای نسبی آب برگ، کاتالاز و پتانسیل اسمزی در گروه‌ اول (mlc8، mlc11، mlc33، mlc47، mlc70، mlc84، mlc409، mlc454 و mlc472) نسبت به میانگین کل برتری داشتند. بنابراین از این ژنوتیپ‌ها به دلیل برتری از نظر بقاء می‌توان در مطالعات تکمیلی تحمل به یخ‌زدگی در شرایط مزرعه در مناطق سرد استفاده نمود.

evaluation of diversity of lentil (lens culinaris medik.) genotypes under freezing stress in controlled conditions

introductionlentil (lens culinaris medik.) is an important legume that plays a significant role in food security and human nutrition in the world. lentils provide protein and fiber, as well as many vitamins and minerals, such as iron, zinc, folate, and magnesium. lentil is a moderately drought tolerant crop, but the yield is drastically reduced with increased drought stress. one of the simplest ways to reduce the effects of drought stress is regulate plant growth period to avoid moisture stress; termed as drought escape; therefore, autumn planting can be effective in reducing the effects of drought stress in lentile. on the other hand, cold and freezing are the most important factor limiting lentil cultivation in autumn planting. considering the importance of autumn planting in cold and highlands areas to use the seasonal rainfall in lentile crop and also due to the diversity among lentil genotypes for cold tolerance and the importance of lentil as a source of high nutritional value, this study was conducted to identify cold tolerant lentils genotypes. materials and methodsthis research was carried out in order to investigate the effective traits in freezing tolerance of lentil genotypes, as factorial based on completely randomized design with three replications under controlled conditions at ferdowsi university of mashhad in 2020. the studied factors included 18 lentil genotypes at four freezing temperatures (0, -15, -18 and -20 °c). the pots were irrigated 24 hours before the freezing stress and then transferred to the thermogradient freezer to apply the tretments in mid-february. the freezer temperature at the beginning of the experiment was 5 °c and after placing the samples with slope of 2 °c per hour the temperature decreased. in order to create ice nucleation in the plant and to avoid the supercooling phenomenon, at 3 °c, ice nucleation active bacteria (inab) were sprayed on the plant. in order to balance the ambient temperature, seedlings were kept in each temperature treatment for one hour and then overnight in a cold room at 5 °c. before exposing the plant to freezing stress, photosynthetic pigments, dpph radical activity, anthocyanin, total phenol, soluble carbohydrates, malondialdehyde (mda), proline content, catalase activity, peroxidase activity, and the relative water content (rwc) of the osmotic potential were measured. three weeks after transferring the samples to the greenhouse, the survival percentage of the samples were evaluated. plant survival percentage was calculated by counting the number of live plants before and after frost stress in each pot. results and discussionthe results showed that lowering the temperature to -18 and -20 °c reduced the survival rate in most genotypes. the highest survival percentage was observed in mlc11 genotype at -18 °c. none of the studied genotypes could withstand temperatures of -20 °c. at -15 °c, mlc13, mlc17, mlc70, mlc409 and mlc454 genotypes had a survival of over 80%. factor analysis showed that the first factor accounted for 31.12% of the changes with chlorophyll a, carotenoids, cha to chb ratio, total photosynthetic pigments and inhibition of dpph free radical activity and the second factor accounted for 18.28% of the changes with chlorophyll b, peroxidase, plant height and biomass justifies. due to these traits, mlc8, mlc13, mlc17, mlc38, mlc84, mlc286 and mlc334 genotypes are considered as high stress tolerance genotypes. analysis of genotype clusters and comparison of group means showed that all traits except soluble carbohydrates, proline, relative leaf water content, catalase and osmotic potential in the first group (mlc8, mlc11, mlc33, mlc47, mlc70, mlc84, mlc4, mlc409, mlc409) they were superior to the total average. conclusionsignificant variations were observed among the genotypes studied in terms of survival rate, regrowth, and antioxidant traits.