بررسی تنوع فنوتیپی در برخی از جمعیت‌های یونجه (medicago sativa l.) با منشاهای مختلف در شرایط آب‌وهوایی ارومیه

یونجه یکی از پرمحصول‌ترین و مغذی‌ترین گیاهان علوفه‌ای است که در سرتاسر جهان برای علوفه، سیلو یا مرتع کشت می‌شود. به‌منظور بررسی تنوع فنوتیپی، آزمایشی با 40 جمعیت یونجه در قالب طرح بلوک‌های کامل تصادفی با سه تکرار طی سال 1398 در مزرعه تحقیقاتی دانشگاه ارومیه اجرا شد. صفات مختلف شامل ارتفاع بوته، سرعت رشد مجدد، تعداد گره، فاصله میان‌گره، تعداد ساقه، تعداد گل در گل‌آذین، طول گل‌آذین، تعداد غلاف در گل‌آذین، وزن تر و خشک برگ، وزن تر و خشک ساقه، وزن تر و خشک کل، نسبت وزن خشک کل به وزن تر کل و نسبت برگ به ساقه اندازه‌گیری شدند. بر طبق نتایج، بین جمعیت‌های یونجه ازنظر اکثر صفات اختلاف معنی‌داری وجود داشت. تجزیه گرافیکی بای‌پلات ژنوتیپ × صفت با توجیه 43/53 درصد از کل تنوع داده‌ها تا حدود زیادی توانست مطالعه تنوع فنوتیپی و روابط میان صفات را تسهیل بخشد. همبستگی مثبت میان دو صفت مهم عملکرد علوفه خشک و نسبت برگ به ساقه منجر به رتبه‌بندی تقریباً یکسان جمعیت‌ها براساس این صفات شد که ازنظر اصلاح همزمان این دو صفت حائز اهمیت است. همچنین جمعیت‌های مطالعه‌شده براساس تجزیه خوشه‌ای به دو گروه اصلی تقسیم شدند و هرکدام در دو زیرگروه قرار گرفتند که زیرگروه اول حاوی توده‌هایی با منشا قره یونجه و خارجی بودند و به لحاظ عملکرد علوفه و نسبت برگ به ساقه در وضعیت مطلوبی قرار داشتند؛ بنابراین، جمعیت‌های موجود در خوشه اول می‌توانند در برنامه‌های توسعه کشت یونجه و برنامه به‌نژادی آتی این گیاه استفاده شوند.

evaluation of phenotypic diversity in some populations of alfalfa (medicago sativa l.) with different origins under urmia climate

alfalfa (medicago sativa l.), one of the most productive and nutritious forage crops, is grown worldwide for hay, silage and pasture. in order to study the phenotypic variation, an experiment was conducted on 40 alfalfa population in a randomized complete block design with three replications during 2018 in a research farm of urmia university. traits including plant height, re-growth rate, no. of node, node length, no. of stem, no. of floret per racemes, racemes length, no. of pod per racemes, leaf fresh weight, leaf dry weight, stem fresh weight, stem dry weight, total fresh weight, total dry weight, leaf dry weight/stem dry weight, and total dry weight/total fresh weight were measured. the results showed a significant variation in alfalfa populations, so that for most of the traits, significant difference was observed. the results showed that graphical analysis of the genotype × trait biplot, explaining 53.43% of the total standardized data variation, could greatly facilitate the study of genetic variation and relationships between traits. the positive correlation between two important traits of total dry weight and leaf to stem ratio led to a nearly identical ranking of the populations based on these traits, which is important for simultaneous breeding of these two traits. further, the studied populations were clustered in two main groups, each of them in two subgroups based on cluster analysis, the first subgroup containing foreign and ghareh-yonjeh populations, and in terms of forage yield and leaf to stem ratio the situation was favorable. therefore, the populations in the first cluster can be used in alfalfa cultivation development programs and the future breeding program of this plant.key words: genotype-by-trait biplot, genetic diversity, forage, classification of alfalfa populations.  introductionalfalfa (medicago sativa l.) is known as the most valuable fodder plant in the world due to its high yield, good fodder quality, tolerance to environmental stress and positive role in soil fertility and structure (biazzi et al., 2017). the local populations of alfalfa in iran have higher genetic diversity and are a valuable source for alfalfa germplasm conservation and breeding programs in the future (rameshknia et al., 2024). knowledge of diversity is the main condition of plant breeding. so far, a wide range of researches have reported phenotypic variation among different domestic and foreign alfalfa populations (abdollahi mandoulakani, 2013; hazegh jafari et al., 2014; benabderrahim et al., 2015; sayed et al., 2022). the purpose of this research was to evaluate alfalfa populations with different origins in terms of phenotypic traits, compare populations in terms of important traits, and analyze the correlation between traits using the genotype × trait (gt) and genotype group × trait (ggt) biplots. materials and methodsan experiment with 40 alfalfa populations of different origin in the form of randomized complete block design (rcbd) with three replications was conducted in a research farm of urmia university in 2018. each population was cultivated in a two-meter line with a distance of 20 cm between two plants. traits including plant height, re-growth rate, no. of node, node length, no. of stem, no. of floret per racemes, racemes length, no. of pod per racemes, leaf fresh weight, leaf dry weight, stem fresh weight, stem dry weight, total fresh weight, total dry weight, leaf dry weight/stem dry weight, and total dry weight/total fresh weight were measured. analysis of variance (anova) was done in sas 9.4 software. the cluster dendrogram was drawn by calculating euclidean square distances and ward’s method in minitab 18. finally, the standardized data of two-way table of genotype×trait and genotype group×trait were analyzed using gt and ggt biplots in ggebiplotsgui r-package. research findingsthe results of anova showed that there was a statistically significant difference between the alfalfa populations studied in terms of all the measured traits except the racemes length. this difference indicates the existence of diversity among alfalfa populations in terms of fodder yield and some morphological and physiological characteristics, the basis of which can be well deciphered with gt biplots. the results showed that graphical analysis of the genotype × trait biplot, explaining 53.43% of the total standardized data variation, could greatly facilitate the study of genetic variation and relationships between traits. population no. 32 had the highest amount in terms of leaf dry weight, stem dry weight, and number of nodes. population no. 2 had the highest amount of fresh and dry weight of leaves, fresh and dry weight of stem, and total fresh and dry weight. also, population no. 16 had the highest number of floret per racemes and the plant height. in the end, population no. 6 was suitable in terms of total dry weight/total wet weight, number of pods per racemes, racemes length, inter-node distance, number of stems, and re-growth rate. the number of nodes, leaf dry weight/stem dry weight, fresh and dry weight of leaf, fresh and dry weight of stem, and total fresh and dry weight were positively correlated with each other. one of the strongest negative correlations is the correlation between leaf dry weight/stem dry weight with the number of stems and re-growth rate. the results of the cluster analysis showed that the studied populations were divided into two main groups, each with two subgroups, based on the studied traits. the first subgroup had 9 populations, half of which were of gareh-yonjeh origin. the second subgroup had 8 populations, which had the highest fodder yield after the first subgroup. the third subgroup included 15 populations and in the fourth subgroup, like the other three subgroups, populations with different origins were placed in one cluster and had 8 populations.discussion of results and conclusionaccording to our findings, considerable diversity in terms of phenotypic traits has been observed in different alfalfa populations (bagavathiannan et al., 2010; moawed, 2016; abdollahi mandoulakani, 2013; khodarahmpour motamedi, 2016; dos santos et al., 2020). iran is one of the centers of origin and diversity of alfalfa. such diversity is very important to face the increasing climatic changes that significantly affect the yield of alfalfa (pourshirazi et al., 2022). the gt biplot technique is a suitable statistical method that can correctly show the relationship between traits (akcura et al., 2016). based on the results, the first component was identified as fodder production component and the second component as reproductive component. populations with high fodder yield and leaf-to-stem ratio were related to gareh-yonjeh and foreign populations. while, except for one case, populations with hamadani origin had average and low performance, and tropical populations were the most unfavorable. the positive correlation between two important traits of total dry weight and leaf to stem ratio led to a nearly identical ranking of the populations based on these traits, which is important for simultaneous breeding of these two traits. further, the studied populations were clustered in two main groups, each of them in two subgroups based on cluster analysis. paying attention to the higher value of the first subgroup in terms of important traits will be of particular importance in breeding programs, and if the goal is to increase yield and improve leaf-to-stem ratio, the populations in this subgroup, especially the gareh-yonjeh populations, are preferred over others and are suitable for the azerbaijan region. finally, considering the positive features of gt biplot, it is recommended to use it in the evaluation of phenotypic diversity.