ارزیابی پاسخ لاین‌های نیمه‌خواهری چغندرقند (beta vulgaris l.) نسبت به تنش خشکی

کمبود منابع آب و بالطبع آن خشکی در زمره شدیدترین عوامل تنش‌زای محیطی قرار دارد که بر رشد و بهره‌وری محصول چغندرقند تاثیر نامطلوبی می‌گذارد. با این وجود، بهره‌وری آب این گیاه را می‌توان با استفاده از ژنوتیپ‌های متحمل در برابر کمبود آب ارتقا بخشید. در مطالعه حاضر به ارزیابی لاین‌های گرده‌افشان چغندرقند که با هدف ایجاد والد‌های پدری متحمل به خشکی طی یک برنامه به‌نژادی مدون در طول چندین سال انجام شده بود، پرداخته شد. بدین منظور آزمایشی با 20 لاین گرده‌افشان و سه لاین شاهد در قالب طرح بلوک‌های کامل تصادفی در دو محیط آبیاری نرمال و تنش خشکی در سال 1393 با سه تکرار اجرا گردید. بر اساس میزان عملکرد ریشه در شرایط نرمال و تنش خشکی شاخص‌های مختلف تحمل و حساسیت به تنش برآورد شدند که در میان آن‌ها شش شاخص بهره‌وری متوسط، بهره‌وری متوسط ژئومتریک، تحمل به تنش، میانگین هارمونیک، عملکرد و مقاومت به خشکی همبستگی مثبت و قابل ملاحظه‌ای با عملکرد ریشه تحت هر دو شرایط نرمال و تنش داشتند. تجزیه به مولفه‌های اصلی عملکرد ریشه در هر دو شرایط و شاخص‌های برآورد شده نشان داد که دو مولفه اول در مجموع بیش از 99 درصد تغییرات را تبیین می‌کند. بر اساس ضرایب به‌دست‌آمده از تجزیه به مولفه اصلی، مولفه اول تحت عنوان مولفه پتانسیل عملکرد ریشه و تحمل به خشکی و مولفه دوم تحت ‌عنوان مولفه حساسیت به خشکی نام‌گذاری شدند. در نهایت بر اساس نتایج حاصله، سه لاین s1– 950077، s1– 950123 و s1– 950116 تحت عنوان متحمل‌ترین لاین‌ها معرفی شدند.

evaluation of the sugar beet (beta vulgaris l.) half-sib lines response to drought stress

introduction: plants face a variety of environmental stresses during their growth and development phase, including biotic and abiotic stress factors. sugar beet growth and productivity are severely affected by the lack of water resources and drought, which are among the most serious environmental stressors. however, the water productivity of sugar beet can be improved by using tolerant genotypes against water scarcity. a multi-year breeding program evaluated sugar beet pollinator lines to create drought-tolerant parents. the study aimed to improve and select drought-tolerant sugar beet pollinator lines.material and methods: in this regard, an experiment was conducted to evaluate the drought tolerance of sugar beet pollinator lines. the experiment was performed in two normal irrigation and drought stress conditions, in 2014. the experiment was conducted in a randomized complete block design in three replications with 20 pollinator lines and three control lines. the root yield was estimated under normal and drought stress conditions, and different stress tolerance and sensitivity indices were calculated based on the results.results and discussion: the obtained results showed that normal and drought stress conditions caused different responses in terms of the root yield of the lines at the 1% probability level. a considerable variation was observed among the lines in terms of the trait at the 1% probability level. genotype-environment interaction also caused a difference in terms of root yield at the 1% probability level. this indicates that the response of lines varies according to different environmental conditions. in other words, the environment causes a change in the yield of the lines from one environment to another. based on the ranking of the lines under normal condition and drought stress, it can be concluded that drought stress caused a decrease in the root yield of the investigated lines by a certain amount. additionally, the ranking of the lines changed significantly under drought stress compared to normal condition. this change in the rank of the lines can indicate the presence or absence of genes that are involved in stress tolerance. therefore, it can be acknowledged that the lines that showed a decrease in root yield under drought stress condition probably carry genes that were inherited from the drought-tolerant parent. the mp, gmp, sti, hm, yi and di had a significant positive correlation with root yield under both conditions. principal component analysis (pca) of root yield in both conditions and estimated indices showed that the first two components together explain more than 99% of the variance. based on the coefficients obtained from pca, the first component was named as the root yield potential component and drought tolerance and the second component was named as the drought susceptibility component. based on the mgidi index, by applying a selection pressure of 15%, s1-950116 ranked first and control 110, and s1-950077 ranked next as the most ideal genotypes in terms of root yield, both normal and stress conditions and 11 stress tolerance and sensitivity indices.conclission: based on the results of correlation analysis, principal component analysis, and the mgidi index, the mp, gmp, sti, hm, yi, and di indices were found to be the most suitable indices for selecting lines with high root yield potential and tolerance in drought stress environments. among the 20 studied pollinator lines, s1-950077, s1-950123, s1-950116, s1-950074, and s1-950119 had the highest tolerance compared to other lines. these lines had the highest root yield potential under both normal and stress conditions, which could be due to the presence of drought tolerance genes inherited from the tolerant maternal parent (fodder beet 7221). therefore, these lines can be suggested as the pollinator parents for the production of drought-tolerant hybrids.