گزینش ژنوتیپ‌های منتخب عدس (Lens Culinaris Medik) متحمل به تنش خشکی با به‌کارگیری پنج شاخص تحمل جدید در شرایط مشهد

به‌منظور ارزیابی و انتخاب ژنوتیپ‌های عدس منتخب متحمل به تنش خشکی و بررسی کارآیی شاخص‌های قدیمی و جدید تحمل به تنش، پژوهشی در سال زراعی 94-1393 در مزرعه تحقیقاتی دانشگاه فردوسی مشهد در قالب طرح بلوک‌های کامل تصادفی با سه تکرار و تحت دو شرایط رطوبتی عدم تنش خشکی (تامین 100درصد نیاز آبی گیاه) و تنش خشکی (تامین 40 درصد نیاز آبی گیاه) بر روی 9 ژنوتیپ برگزیده از بین 73 ژنوتیپ مورد بررسی در آزمایش زراعی سال قبل، اجرا گردید. برای اعمال دقیق محدودیت آبی، از سیستم آبیاری قطره‌ای نواری استفاده شد و میزان آب ورودی توسط کنتور مورد پایش قرار گرفت. بر اساس نتایج، در شرایط بدون تنش، ژنوتیپ‌های mlc356 و mlc121 به ترتیب، با تولید 2621 و 993 کیلوگرم دانه در هکتار، بالاترین و پایین‌ترین رتبه تولید دانه در واحد سطح را به خود اختصاص دادند. در شرایط تنش نیز ژنوتیپ‌های‌ cabralinta و mlc121 به‌ترتیب، با تولید 876 و 288 کیلوگرم دانه در هکتار، بالاترین و پایین‌ترین رتبه تولید دانه در واحد سطح را کسب کردند. ارزیابی تحمل به تنش خشکی، بر اساس هشت شاخص قدیمی (di،yi، gmp، sti، mp، gmp، tol، hm و rei) و پنج شاخص جدید (k1sti، snpi، ati، sspi و k2sti) صورت گرفت. مطالعۀ همبستگی بین عملکرد دانه در شرایط تنش و عدم تنش و شاخص‌های تحمل به خشکی نشان داد که شاخص جدید k2sti و شاخص‌های قدیمی sti، gmp، rei، hm و mp برای شناسایی ژنوتیپ‌هایی با عملکرد بالا در هر دو شرایط رطوبتی (تنش و بدون تنش) مناسب هستند. تجزیه به مولفه‌های اصلی و ترسیم بای‌پلات نیز نشان داد که شاخص‌های جدید snpi و k2sti و شاخص‌های قدیمی yi، hm، gmp، rei و sti بهترین شاخص‌ها برای جداسازی ژنوتیپ‌های در هر دو شرایط رطوبتی هستند و بر این اساس، ژنوتیپ‌های cabralinta، mlc356 و mlc025 به‌عنوان ژنوتیپ‌های متحمل به تنش خشکی و با عملکرد بالا انتخاب شدند. برای گروه‌بندی ژنوتیپ‌ها، تجزیه خوشه‌ای انجام گرفت و رسم دندروگرام، ژنوتیپ‌ها را به چهار کلاستر گروه‌بندی کرد که در این گروه‌بندی، cabralinta و mlc025 در یک کلاستر (کلاستر دوم) قرار گرفتند.

Selection of sieved drought tolerant lentil (Lens culinaris Medik) genotypes via five new tolerance indices in Mashhad conditions

IntroductionDrought is one of the most important stresses which reduce yields of crops and is one of the most important production constraints in arid and semiarid regions. Iran with annual mean rainfall of 257 mm was classified among the arid regions of the world. Lentil is a pulse crop, rich in proteins and have 18 of the 20 amino acids including all 8 essential amino acids. Thus, lentils play an important role in human diet, especially in lowincome people in the developing countries. In Iran, lentil is usually grown in rainfed areas. The average lentil yield in Iran is 476 and 1195 Kg.ha1 in rainfed and irrigated farms, respectively. Identification of droughttolerant genotypes is essential for cultivation in arid areas. To identify and select tolerant genotypes, researchers have proposed many drought indices based on a mathematical relationship between grain yield under stress and nonstress conditions, which are based on tolerance or susceptibility to drought genotypes. The aim of this study was to identify indicators that can identify highyielding and drought tolerant genotypes in rainfed conditions of Mashhad. Materials and MethodsThis research was carried out at the Agricultural Research Station, Ferdowsi University of Mashhad, during growth season 2015. In this research, nine genotypes were used that eight genotypes of them were relatively drought tolerant in stress conditions and one genotype (MLC121) susceptible to drought stress were cultivated. These genotypes were selected from 73 genotypes including native populations and ICARDA genotypes in the seed bank of the Ferdowsi University of Mashhad, which were planted in the same plot at last year. Experiments were conducted as completely randomized design with nonstress and drought stress conditions (providing 100% and 40% water requirement of the plant) with three replications. Results and DiscussionThe analysis of variance showed a significant difference between yield genotypes in nonstress and drought stress conditions. Based on the results, in nonstress conditions, MLC356 and MLC121 genotypes produced the highest and lowest grain yields per hectare with 2621 and 993 kg.ha1 respectively. Under stress conditions, Cabralinta and MLC121 genotypes produced the highest and lowest grain yields per hectare with 876 and 288 kg.ha1, respectively. The mean yield of genotypes in nonstress and stress condition were 1616.7 and 625.6 kg.h1, respectively that showed a decrease of 61.3% in water stress condition. Correlation between yields in stress and nonstress condition with tolerance indices showed that the old indices of STI, GMP, REI, HM and MP and the new K2STI index had a positive and significant correlation with yield in stress and nonstress conditions. The 3D Charts of the K2STI index with Yp and Ys showed that MLC356, Cabralinta and MLC025 genotypes had the highest rate of this index under nonstress and drought stress. The biplot drawing showed that high yielding genotypes are in D region. In this area, the old indices of YI, HM, GMP, REI, STI, the new indicators of SNPI K2STI and all of which are consistent with the Ys. The sharp angle between Ys, SNPI and YI indices shows a strong and positive correlation between these indices and indicates their superiority in separating hightolerance genotypes with stress conditions and having relatively high performance in nonstress conditions. Considering this criterion, Cabralinta, MLC025, and MLC356 genotypes which had the highest correlation with the two indices, can be selected. ConclusionIn all, the results of this study showed that SNPI and YI indices have a high correlation (99.9%) with performance in stress conditions, as well as K2STI, HM, GMP, REI and STI indices, all of which in D area. They have the most positive and significant correlations with each other and with performance in two conditions of nonstress and stress as the most suitable and effective criteria for identifying and selecting genotypes tolerant to drought stress. In all, if the goal is to introduce three genotypes, Cabralinta, MLC025 and, MLC356 genotypes which are the most susceptible genotypes are suggested compared to the stress conditions, but if the goal is to introduce only one genotype, Cabralinta genotype that has the highest and most stable yield under stress condition and in comparison with MLC356 genotype under stress conditions, 10.2% more yield could be introduced for arid and severe stress areas. For lentil planting in areas with mild stress, a high yielding genotype and tolerant, MLC356 genotype is recommended. It is also suggested that again to increase the accuracy of the experiment, three selected genotypes are again cultivated in the field.