تجزیه ژنتیکی عملکرد و صفات مرتبط با عملکرد گندم نان (.triticum aestivum l) تحت شرایط آبیاری کامل و تنش خشکی دوره زایشی

به‌منظور تجزیه ژنتیکی عملکرد و برخی صفات مورفولوژیک گندم نان هشت رقم گندم نان شامل استار، تیرگان، احسان، شیرودی، بم، تجن، یانگ و اکبری در یک بلوک تلاقی کشت شدند و تلاقی‌های مستقیم بین هشت رقم مذکور به‌منظور تولید نسل ‌f1 انجام شد. نتاج حاصل از تلاقی به همراه والدین آن‌ها در قالب طرح بلوک‌های کامل تصادفی با سه تکرار در ایستگاه تحقیقات کشاورزی گرگان تحت دو شرایط آبیاری کامل و تنش خشکی دوره زایشی در سال زراعی 1400-1399 مورد ارزیابی قرار گرفتند. اعمال تنش خشکی انتهایی در مرحله ظهور کامل سنبله (زادوکس 60) انجام شد. نتایج تجزیه واریانس مرکب صفات در دو محیط عادی و تنش خشکی دوره زایشی نشان داد که اثر متقابل ژنوتیپ×محیط برای صفات عملکرد دانه، عملکرد بیولوژیک و وزن صد دانه معنی‌دار بود. بیشترین مقادیر ترکیب‌پذیری عمومی در صفات عملکرد بیولوژیک، عملکرد دانه، شاخص برداشت، تعداد دانه در سنبله و وزن صد دانه در هر دو شرایط آبیاری کامل و تنش خشکی مربوط به رقم تیرگان بود. حداکثر ترکیب‌پذیری خصوصی عملکرد دانه در شرایط آبیاری کامل مربوط به تلاقی تجن×اکبری بود. تحت شرایط تنش خشکی تلاقی بم×اکبری در صفت عملکرد بیولوژیک و عملکرد دانه حداکثر ترکیب‌پذیری خصوصی را داشت از طرفی در صفات وزن صد دانه، شاخص برداشت و تعداد دانه در سنبله نیز ترکیب‌پذیری خصوصی بالایی داشت و به‌عنوان تلاقی مطلوب تحت تنش خشکی شناخته شد. به طور کلی در صفات عملکرد دانه، عملکرد بیولوژیک و وزن صد دانه وراثت‌پذیری خصوصی در شرایط تنش کمتر از شرایط آبیاری کامل بود. نتایج این پژوهش نشان داد که در هر دو شرایط آبیاری کامل و تنش خشکی می‌توان بهبود ژنتیکی صفات ارتفاع بوته و طول پدانکل را در نسل‌های مقدماتی نتاج این تلاقی‌ها انجام داد، در حالی که در سایر صفات بایستی انجام گزینش تا نسل‌های پیشرفته ادامه‌ یابد.

genetic analysis of yield and yield related traits in bread wheat (triticum aestivum l.) under complete irrigation and drought stress in reproductive phase conditions

introductionwheat performance is always affected by climate change and environmental stresses such as drought stress. development of high-yielding cultivars requires genetic diversity. awareness about heritability of traits can be helpful in determining the appropriate breeding strategy for any environmental conditions. by progeny trial after a diallel crossing, the function of genes and inheritance of quantitative traits can be estimated. this increases the ability to select parental lines, to participate in crosses, and determines the management of generations in the segregating populations. materials and methodsin order to understand the genetic structure of grain yield and some morphological traits of bread wheat under normal and drought stress conditions, eight bread wheat cultivars including star; tirgan; ehsan; shirodi; bam; tajan, yang and akbari were planted in the crossing block and direct crosses were performed among the eight cultivars to produce f1 generation. this research carries out in gorgan agricultural research station in 2020-2021 cropping season, under normal and drought stress conditions. the progenies of the crosses with their parents were evaluated based on a randomized complete block design (rcbd) with three replications. imposing stress by terminating irrigation was initiated at the zadoks 60 (full heading emergence) stage. results and discussioncombined analysis of variance under normal and drought stress conditions showed that the simple effects of genotype and environment were statistically significant in all traits. also, the interaction effects of genotype×environment was statistically significant for grain yield, biological yield and 100-kernel weight. in fact, for these traits the response of genotypes was different under normal and stress conditions. analysis of variance of griffing’s diallel method showed a statistically significant difference between genotypes in all studied traits. therefore, among the progenies of the crosses it is possible to select superior genotypes. in biological yield and grain yield under both normal and drought stress conditions, tirgan cultivar had the highest general combining ability, while star cultivar showed the lowest general combining ability. tirgan cultivar can be used to increase grain yield and biological yield under both conditions. in plant height, peduncle length and harvest index, tajan×yang, ehsan×shirodi and bam×yang crosses had the maximum specific combining ability, respectively. in other traits, in each condition, an individual cross had the highest specific combining ability. under normal conditions, tajan×akbari cross had the highest specific combining ability in grain yield. under drought stress conditions, bam×akbari cross had the highest specific combining ability in biological yield and grain yield, it simultaneously had a high specific combinability in 100-grain weight, harvest index and number of grains per spike. therefore, bam×akbari cross was determined as the best cross in genetic improvement of desirable agronomic traits with high specific combining ability in yield and yield components, under drought stress conditions. the ratio of additive variance from genetic variance for plant height and peduncle length was greater than dominance variance. subsequently, the highest narrow-sense heritability in both normal and drought stress conditions was related to plant height and peduncle length. in both normal and drought stress conditions, the highest degree of dominance was related to harvest index traits and number of grains per spike, respectively. therefore, in these traits the lowest narrow-sense heritability, the lowest baker’s genetic ratio and the highest ratio of dominance variance from genetic variance were observed in both normal and drought stress conditions. in grain yield, a high ratio of dominance variance from genetic variance was assigned under normal (84%) and drought stress (88%) conditions, hence low narrow-sense heritability was observed under normal (8%) and drought stress (5%) conditions. in general, in grain yield, biological yield and 100-kernel weight, narrow-sense heritability was lower under drought stress conditions, compared to normal conditions, which indicates a greater ratio of non-additive effects under drought stress conditions. conclusionthe results of this study showed that under both conditions, tirgan cultivar had the highest general combining ability in grain yield and biological yield. tajan×akbari and bam×akbari crosses were determined as the best cross in genetic improvement of desirable agronomic traits with high specific combining ability in yield and yield components, under normal and drought stress conditions, respectively. in grain yield, biological yield and 100-kernel weight, narrow-sense heritability was lower under drought stress conditions, compared to normal conditions. based our results under both conditions in the progenies of the crosses, genetic improvement can be done in plant height and peduncle length in the initial generations, but for other traits including grain yield and its components, selection should be postponed to more advanced generations.