چكيده فارسي :
به‌منظور مطالعه كارآیی مصرف آب و شاخص‌های تحمل به تنش خشكی، 10 لاین در حال نامگذاری گندم مناطق سرد در یك طرح كرت‌های خرد شده در قالب بلوك‌های كامل تصادفی با سه تكرار به مدت دو سال زراعی (1389-1387) در ایستگاه تحقیقاتی طرق مشهد مورد مقایسه قرار گرفتند. فاكتور محدودیت رطوبتی (آبیاری كامل، قطع آبیاری از مرحله شیری دانه تا انتهای رشد و نمو گندم و قطع آبیاری از مرحله ظهور بساك تا انتهای رشد و نمو گندم) در كرت‌های اصلی و 10 لاین امیدبخش گندم در كرت‌های فرعی قرار گرفت. نتایج نشان داد عملكرد دانه در تیمارهای قطع آبیاری از مرحله شیری دانه تا انتهای رشد و نمو گندم L2)) و قطع آبیاری از مرحله ظهور بساك تا انتهای رشد و نمو گندم (L3) به‌ترتیب 6/18و 3/45 درصد نسبت به شرایط بهینه رطوبتی كاهش پیدا كرد. مقایسه ژنوتیپ نشان داد كه ژنوتیپ‌های V5، V4و V10 به‌ترتیب با 885/1، 756/1 و 833/1 كیلوگرم در متر مكعب، بیشترین كارآیی مصرف آب را دارا بودند. نتایج نشان داد شاخص فرناندز (STI) برآورد نزدیكتری از عملكرد در شرایط تنش (**93/0 = r) و بهینه (**50/0= r) ارائه نمود. در شرایط قطع آبیاری از مرحله شیری دانه تا انتهای رشد و نمو گندم L2)) براساس شاخص تحمل (STI) ژنوتیپ‌های V5، V4، V10، V7 و V8 و در شرایط قطع آبیاری از مرحله ظهور بساك تا انتهای رشد و نمو گندم (L3) ژنوتیپ‌های V5، V4 و V10 به‌ترتیب بالاترین شاخص تحمل به تنش رطوبتی را دارا بودند، بنابراین باتوجه به برتری ژنوتیپ‌های V5، V4 و V10 از نظر كارآیی مصرف آب و شاخص تحمل به تنش محدودیت رطوبتی می‌توان آنها را برای شرایط مشابه این بررسی توصیه نمود.
چكيده لاتين :
Introduction
During growth stages of wheat, anthesis and grain filling periods are the most susceptible to drought. Wheat cultivars that are more tolerant to terminal drought are more suitable to Mediterranean conditions. To increase water use efficiency, the target environment should be taken into account, because one trait might be effective in an environment but ineffective in another environment. In general, some traits like early vigour and root absorbtion capacity are so important in water deficient conditions. In recent years, increasing grain yield was due to increasing grain numbers. Although both the source and sink is considered as the limitation factors in increasing grain yield in old cultivars, even in the new cultivars sink seems to be more important. In fact, phenological adjustment adapted with seasonal precipitation pattern can improve water use efficiency in drought conditions. Suitable flowering time is the most important trait that is correlated with increasing water use efficiency in drought conditions.
Materials and Methods
In order to evaluate the level of drought tolerance in promising bread wheat lines, a split plot arrangements using randomized complete block design with three replications was carried out in 2008-09 and 2009-10 growing seasons at Torogh Agricultural Research Field Station, Mashhad. in. water limited conditions at three levels Optimum moisture conditions (L1), removal irrigation and using rain shelter from milky grain stage to maturity (L2), removal irrigation and using rainshelter from anthesis to maturity (L3) were assigned to main plots. Ten bread wheat lines include suitable for cold and dry regions (V1: (Toos), V2: (C-81-10), V3: (pishgam), V4: (C-84-4), V5: (C-84-8), V6: (C-D-85-15), V7: (C-D-85-9), V8: (C-D-84-5502), V9: (C-D-85-5502) and V10: (C-85-6) were randomized in sub-plots. Stress susceptibility index (SSI), stress tolerance index (STI) and tolerance (TOL) were calculated using following equations:
D = 1- (Yd/Yp), SSI = (1-(Ydi/Ypi)) / D, STI = (Ypi×Ysi)/ (Yp) 2, TOL= Ypi – Ysi
In which D is environment stress intensity; Yp, average of grain yield for all genotypes in optimum; Ys, in water limited conditions; Ypi, grain yield of one genotype in optimum; and Ysi, grain yield of one genotype in water limited conditions.
Anthesis and physiological maturity were determined by observing of anthers in %50 spikes and changing color of %50 pedancles to yellow, respectively.
Results and Discussions
The results revealed that water stress (L2 and L3 treatments) reduced grain yield (18.6% and 45.3%, respectively). Genotypes V5, V4 and V10 showed maximum water use efficiency (WUE) (1.885, 1.756 and 1.833 kg.m-3 respectively). A highly significant relationship was found between grain yield under moisture limited conditions and STI (r = 0.93**) and TOL (r = 0.85**). Grain yield under optimum irrigation condition was significantly (r = 0.50**) correlated with STI.
Therefore, stress tolerance index (STI) was more efficient index for estimation the grain yield under either conditions as well as grouping the genotypes with higher grain yield and tolerant to water limited condition. So, stress tolerance index (STI) was suitable for classifying the higher yielding genotypes adapted to drought prone environment. Since stress tolerance index (STI) was highly and significantly associated with grain yield in both optimum (r = 0.50**) and limited moisture (r = 0.93**) conditions, it can be used an efficient index for evaluation in the field.
Conclusions
Our results indicated that genotypes V5, V4 and V10 with high stress tolerance index (STI) values and the greatest WUE, had the best performance among the other genotypes, respectively. These cultivars had higher grain yield in both optimum and stress conditions than other genotypes So, these cultivars could be recommended to cultivate for similar conditions.
