بررسی عملکرد و اجزاء عملکرد اکوتیپ‌های مختلف زیره سبز (cuminum cyminum l.) تحت تاثیر تنش خشکی

تنش خشکی، تولید زیره در ایران را خصوصاً در مراحل گل‌دهی با چالش جدی مواجه می کند. لذا، به‌منظور بررسی عملکرد و شناسایی منابع ژنتیکی متحمل، 15 اکوتیپ زیره سبز (cuminum cyminum l.) در دو آزمایش جداگانه در قالب طرح بلوک کامل تصادفی با سه تکرار، در دو سال زراعی متوالی 1400- 1398) در کرج مورد ارزیابی قرار گرفتند. در آزمایش نرمال، از کاشت تا پایان دوره رشد و در آزمایش تنش خشکی، از کاشت تا 50 درصد گل‌دهی آبیاری گردیدند. نتایج نشان داد که تنش خشکی موجب کاهش عملکرد و اجزاء عملکرد اکوتیپ های زیره سبز شد. بیشترین عملکرد دانه، (103 گرم در مترمربع) مربوط به اکوتیپ تربت جام 8 در شرایط آبیاری نرمال بود که با اکوتیپ های افغانی، خراسان-بیرجند، یزد 7، تربت جام 9 و سبزوار در یک گروه آماری قرار گرفتند. کمترین مقدار این شاخص (65.8 گرم در مترمربع) مربوط به اکوتیپ خراسان رضوی 12 بود. عملکرد دانه اکوتیپ افغانی، در شرایط آبیاری نرمال و تنش خشکی یکسان بود. اکوتیپ خراسان رضوی 12 نیز اکوتیپ حساس به تنش خشکی بود، زیرا کمترین عملکرد بیولوژیک و عملکرد دانه را در شرایط تنش خشکی داشت. تنش خشکی موجب افزایش درصد اسانس و کاهش عملکرد اسانس زیره سبز نسبت به آبیاری نرمال شد و در میان اکوتیپ ها، بیشترین درصد اسانس زیره سبز مربوط به اکوتیپ افغانی بود. تنش خشکی، کاهش عملکرد اکوتیپ های مورد مطالعه زیره سبز را به همراه داشت، امّا در این میان، اکوتیپ افغانی را می توان به‌عنوان اکوتیپ مقاوم به تنش و دارای اسانس مطلوب معرفی کرد.

exploring the impact of drought stress on the yield and yield components of cumin (cuminum cyminum l.) ecotypes

introductiondrought stress poses a significant challenge to cumin production in iran, particularly during the flowering and seed-setting stages. cumin is a valuable crop with numerous medicinal properties and applications in various industries. despite its short growing season, the economic importance of cumin makes it imperative to find ways to mitigate the effects of drought stress on seed yield. addressing the negative effects of drought stress is crucial for improving cumin seed yield. one effective strategy is to identify drought-resistant cumin cultivars. by selecting cultivars that are more resilient to drought conditions, farmers can enhance their chances of achieving higher yields, even in challenging environments. materials and methods this two-year study (2020-2021) aimed to assess the drought tolerance of 15 cumin ecotypes under field conditions in karaj, iran. the experimental design was a randomized complete block design with three replications. the ecotypes evaluated were: tabriz, torbat jam 8, afghani, khorasan-birjand, yazd 7, yazd 8, torbat jam 9, khorasan razavi 8, pakistan, isfahan, hindi, khorasan razavi 12, isfahan 13, sabzevar, torbat heydarieh. two treatments were applied: full irrigation and drought stress. irrigation under full irrigation was carried out every 10 days according to soil and weather conditions, while irrigation was withheld from 50% flowering to the end of the growth period under drought stress.results and discussion the results of this study showed that drought stress reduced the yield and yield components of cumin ecotypes but increased the essential oil content. the highest seed yield of 102.78 g m-2 was achieved by the ecotype turbat jam 8 under full irrigation conditions, which was statistically similar to the ecotypes afghani, khorasan-birjand, yazd 7, turbat jam 9, and sabzevar under normal irrigation conditions. the lowest seed yield of 65.8 g m-2 was recorded for the ecotype khorasan razavi 12. these results demonstrate the differential tolerance of cumin ecotypes to drought stress and highlight the potential of turbat jam 8 as a drought-tolerant ecotype. the afghani ecotype proved to be drought-resistant, showing consistent grain yield under both normal irrigation and drought stress. conversely, the khorasan razavi 12 ecotype was vulnerable to drought stress, exhibiting reduced biological and grain yields under these conditions. notably, a strong positive correlation (0.973) was observed between essential oil content and seed yield, indicating that breeding for high essential oil content could also improve drought resistance and yield. in addition to the strong correlation between essential oil content and seed yield, other correlations were observed. the amount of essential oil was positively correlated with the harvest index (0.787) and the weight of one thousand seeds (0.721). seed yield also showed positive and significant correlations with the number of umbrellas per plant (0.396), harvest index (0.287), and the number of seeds per umbrella (0.232). no other traits showed significant correlations. biological performance had positive and significant correlations with plant height, number of branches per plant, number of umbels per plant, number of umbels per umbel, and number of seeds per umbel. according to the result of cluster analysis based on ward’s method, the ecotypes were divided into three groups. the highest number of ecotypes was in the third group (7 ecotypes) and the second group (6 ecotypes).