تجزیه مسیر و تحلیل همبستگی عملکرد دانه و اجزاء آن در ژنوتیپ‌های سورگوم دانه‌ای (sorghum bicolor l.) تحت شرایط تنش خشکی

به‌منظور بررسی تنوع و روابط موجود بین صفات با‌ عملکرد و اجزای عملکرد دانه تحت شرایط تنش خشکی در ژنوتیپ‌های سورگوم دانه‌ای، آزمایشی به‌صورت کرت‌های خردشده در قالب طرح بلوک‌های کامل تصادفی در سه تکرار، در مزرعه مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی خراسان جنوبی طی دو سال زراعی 1393 و 1394 اجرا شد. تیمارهای تنش شامل آبیاری معمول، قطع آبیاری در مرحله رشد رویشی (رویت آخرین برگ به‌صورت لوله‌ای) به‌عنوان تنش شدید و قطع آبیاری در مرحله رشد زایشی (50 درصد بوته‌ها در مرحله گل دهی) یا تنش متوسط به‌عنوان عامل اصلی و 10 ژنوتیپ سورگوم دانه‌ای شامل سپیده،kgs29،mgs2 ،kgs33 ، kgfs27،mgs5 ،kgfs5 ،kgfs17 ، kgfs13 و kgfs30 به‌عنوان عامل فرعی در نظر گرفته شدند. ژنوتیپ‌ها ازنظر اغلب ویژگی‌های موردبررسی، تفاوت آماری معنی‌داری نشان دادند که حاکی از وجود تنوع بالا در بین ژنوتیپ‌ها است. برهمکنش تنش خشکی و ژنوتیپ در دو سال آزمایش نشان می‌دهد که ازنظر عملکرد دانه ژنوتیپ kgfs13 در شرایط تنش ملایم و آبیاری نرمال به همراه kgfs17 در شرایط آبیاری نرمال بیشترین و ژنوتیپ kgfs5 در شرایط تنش خشکی شدید کمترین عملکرد دانه را دارا بود. بر اساس تجزیه علیت، در شرایط نرمال، وزن هزار دانه بیشترین تاثیر مستقیم را بر عملکرد دانه داشت‌، درحالی‌که تعداد دانه در پانیکول از طریق وزن هزار دانه بیشترین تاثیر غیرمستقیم و منفی بر عملکرد داشت. همچنین در شرایط تنش خشکی متوسط، ارتفاع گیاه بیشترین تاثیر مستقیم را بر عملکرد دانه داشت درحالی‌که ارتفاع گیاه از طریق وزن هزار دانه تاثیر غیرمستقیم بر عملکرد داشت.

correlation and path analysis in yield and its components in grain sorghum genotypes (sorghum bicolor l.) under water stress conditions

introduction: drought stress is a major problem in the productivity of crops around the world. growth of sorghum in dry and semi-arid regions is affected by water stress at the late stages of growth, such as anthesis, which has negative effects on yield. information about the significant correlation between traits is important for starting a breeding program. because it allows the selection of desired genotypes with desirable traits simultaneously.  due to the increasing spread of  livestock  and  the development of the cultivated area of ​​this plant, which is a relatively drought-tolerant plant, it is very important  to carry out breeding  and  agronomic  research in the south khorasan region, especially in birjand. the objectives of this research were to: a) determine the grain yield relationships with  its components using the stepwise regression method; b) investigate the relationships between traits using  path analysis.materials and methods: a field experiment was carried out using a split plot design with 3 replications. main plots include drought stress treatments while the sub-plots consisted of 10 genotypes of sorghum  including  kgs29, mgs2, sepideh, kgfs27, mgs5, kgfs5, kgfs17, kgfs13 and kgfs30.each plot consisted of  four  lines with  length of  6 meters and a distance between the lines of  60 cm and  the area of ​​each  plot was 14 square meters. plant spacing on the row  was considered as 10 cm. to determine grain yield and biological yield and  harvest  index after  removing  two lines of margin and  half a meter of  the beginning and the end of each  plot were harvested  from a surface of three square meters. after drying  in a ventilated  oven  at 72 ° c for 72 hours, total dry weight and biological yield were determined and then the samples were weighed and the seeds were weighed and the harvest index was calculated. after  data collecting,  the data were analysed , using sas software  to investigate the diversity of  traits among the cultivars and    lines. calculation of correlation coefficient between traits and stepwise regression was performed  using spss software. to distinguish the direct and indirect effects of important traits, path analysis was used .results and discussion: results from combined analysis showed that cultivars and lines were significantly different at %1 level for all traits that is from variation between studied lines and cultivars. comparison of interaction between genotype and stress about grain yield indicated that genotype kgfs13 in medium and normal drought stress, commonly with genotype kgfs17 in normal condition had the highest level and genotype kgfs5 in sever stress condition had the lowest grain yield respectively. in drought stress condition, based on path analysis, thousand kernel weight had the highest direct effect on grain yield in normal condition. while number of seeds per panicle, had indirect effect via 1000-seeds weight on grain yield. the plant height had the highest direct effect on grain yield in medium dry condition. while the plant height, had indirect effect via 1000-seeds weight on grain yield.  conclusion: according to the results of the correlations between the studied traits, under normal (no stress) conditions, plant height, number of seeds per panicle and 1000-seed weight can be used  to improve grain yield. under moderate water stress conditions, plant height and 1000-seed weight had the largest contribution  in determination of the  genotypes diversity.based on path analysis, thousand kernel weight had the highest direct effect on grain yield in normal condition. while number of seeds per panicle, had indirect effect via 1000-seeds  weight on grain yield. the plant height had the highest direct effect on grain yield in medium dry condition. while the plant height, had indirect effect via 1000-seeds  weight on grain yield.