تعیین شاخص‌های انتخاب مناسب برای اصلاح عملکرد دانه در گشنیز (.Coriandrum Sativum L) تحت شرایط بدون تنش و تنش خشکی

برای بهبود صفت پیچیده‌ای مانند عملکرد، یکی از موثرترین روش‌ها در گزینش ژنوتیپ‌های مطلوب، استفاده از گزینش غیرمستقیم برای عملکرد از طریق اجزای عملکرد و صفات وابسته به عملکرد می‌باشد. در این مطالعه به‌منظور درک روابط ژنتیکی بین خصوصیات کمی و کیفی گشنیز و انتخاب شاخص‌های گزینش غیرمستقیم، نتاج حاصل از تلاقی‌‎ دی‌آلل 6 ژنوتیپ گشنیز در نسل‌های f1 و f2 موردارزیابی قرار گرفتند. ژنوتیپ‌های مورد‌بررسی در سه شرایط متفاوت آبیاری به‌طور جداگانه در قالب طرح بلوک‌های کامل تصادفی با سه تکرار در هر آزمایش در سال زراعی 95-1394 مورد ‌ارزیابی قرار گرفتند. صفات ارتفاع گیاه، تعداد برگ، تعداد شاخه در گیاه، تعداد چتر در گیاه، تعداد چتر بارور در گیاه، تعداد دانه در گیاه، وزن هزار دانه، وزن دانه در گیاه یا عملکرد دانه، عملکرد بیولوژیک، میزان اسانس دانه، میزان روغن دانه، عملکرد اسانس، عملکرد روغن، محتوای کلروفیل spad، کلروفیل a، کلروفیل b، کلروفبل کل، کارتنوئید، میزان رطوبت نسبی و نشت یونی مورد اندازه‌گیری قرار گرفتند. نتایج نشان داد که صفات روز تا گلدهی، محتوای کلروفیل spad، میزان رطوبت نسبی، تعداد دانه و وزن هزار دانه با توجه به همبستگی ژنتیکی معنی‌دار با عملکرد دانه و داشتن کنترل ژنتیکی افزایشی و وراثت‌پذیری خصوصی بالا، می‌توانند به‌عنوان شاخص‌های مناسب در برنامه‌های اصلاحی برای انتخاب ژنوتیپ‌های با عملکرد دانه بالا در شرایط تنش خشکی در مزرعه مورد استفاده قرار گیرند. همچنین با توجه به همبستگی ژنتیکی مثبت بین عملکرد دانه با سایر صفات مهم اقتصادی (میزان اسانس دانه، میزان روغن دانه، عملکرد اسانس و عملکرد روغن) در شرایط بدون تنش و تنش خشکی می‌توان نتیجه گرفت که بهبود عملکرد دانه باعث بهبود همزمان صفات اقتصادی دیگر می‌شود.

Determination of suitable selection indices for improving fruit yield in coriander (Coriandrum sativum L.) under non stress and drought stress conditions

Introduction Coriander is an annual herb belongs to the umbel family and is native from North Africa to southwestern of Asia. Coriander is one of the important medicinal plants that used in the pharmaceutical industry and it mainly cultivated and widely distributed for the fruits. The dried fruits are widely employed as a condiment, especially for flavoring of sauces, meat products and bakery and confectionery items. Also, coriander fruits are as a source of essential oils and fatty oil. Water deficit stress is one of the most important factors limiting the growth and survival of the plants in arid and semiarid regions in the world. Water is a major component of the plant materials and significantly influence the quantity and quality of plant production. Drought stress leads to significant changes in the yield and composition of essential oils in aromatic and medicine plants. So that, it was reported that water deficit increased essential oil content but decreased essential oil yield in coriander. Iran with an average annual rainfall of 240 mm is classified as arid and semiarid regions of the world. However, Iran is one of the world’s commercial coriander producers. Coriander has been cultivated for many years in different parts of Iran. Therefore, development of droughttolerant cultivars with high essential oil and fatty oil yield is important in coriander. Indirect selection through yield components and yieldrelated traits is one of the most effective methods for improving complex traits such as fruit yield. Therefore, this research was conducted in order to understand the genetic association between quantitative and qualitative traits and also to identify the indirect selection indices for selection appropriate genotypes in coriander. Materials and Methods F1 and F2 generations derived from halfdiallel crosses between six endemic coriander genotypes including Isfahan, Hamedan, Bushehr, Mazandaran, Markazi and Alborz, along with with their parents were evaluated in three irrigation regimes through randomized complete block design with three replications in each experiment during the growing season in 2016. Plants were grown in different irrigation regimes: wellwatered (WW), moderate drought stress (MDS) and severe drought stress (SDS). The plant height, leaf number, branch number per plant, umbel number per plant, fertile umbel number per plant, fruit number per plant, thousand fruit weight, fruit yield, biological yield, essential oil content, fatty oil content, essential oil yield, fatty oil yield, SPAD chlorophyll content, chlorophyll a, chlorophyll b, total chlorophyll, carotenoids, relative water content and ion leakage were measured. Results and Discussion Results showed that fruit yield had the significant positive genetic correlation with days to flowering, SPAD chlorophyll content, relative water content, fruit number per plant and thousand fruit weight. Therefore, these traits could be used as suitable criterion for selection to increase fruit yield in drought stressed conditions. Consideration, the genetics of early ripening and fruit yield and a significant positive genetic correlation between days to ripening and fruit yield, improving coriander fruit yield under drought stress may be possible through breeding for drought escape. There were the positive genetic correlations between fruit yield and other economical traits in different irrigation regimes. Therefore, improving fruit yield can simultaneously be led to improve in the economical traits. Conclusion Generally, the results indicated that traits of days to flowering, SPAD chlorophyll content, relative water content, fruit number per plant and thousand fruit weight could be used as suitable criterion for selection to increase fruit yield in drought stressed conditions. Also, improving fruit yield can simultaneously be led to improve in the economical traits in both the nonstressed and drought stressed conditions