بررسی تنوع لاین های اصلاحی خیار از طریق تجزیه به عامل ها و تجزیه خوشه ای

Introduction Cucumber (Cucumis sativus L.) is an annual plant in the Cucurbitaceae family, which has ۹۰ genera and ۷۵۰ species. Iran, with an under-cultivation area of ۸۹,۶۳۲ hectares and a production rate of ۱,۸۰۴,۱۸۴ tons of cucumbers, yield of ۲۰۱,۲۸۹ tons per hectare, and it is the third largest cucumber producing country in the world in terms of production. Use of fruits of these vegetable is different depending on the country and the consumer's taste and demand, and it is cultivated for fresh consumption as well as processing (pickled vegetables or cucumbers). The utilization of local genotypes or unmodified native reserves for production has led to very low yield of cucumbers in some countries of the world. The general objectives of cucumber breeding are resistance to diseases and pests, fruit quality and yield increase. Considering the history of cultivation of this product in Iran and due to the large under-cultivation areas of cucumber in the country, little breeding research has been done on this product and the country's required seeds are supplied annually through imports. Therefore, practical and applied research on the breeding of cucumber plant seems necessary. The present study was conducted to evaluate ۲۷ cucumber plant lines using factor analysis and cluster analysis as a tool to identify superior genotypes and more effective traits.   Materials and Methods This study was carried out in the research greenhouse of Department of Horticultural Sciences, Faculty of Agricultural Sciences, University of Guilan, with a longitude of ۴۹ degrees and ۳۶ minutes east and latitude ۳۷ degrees and ۱۶ minutes north with a height of ۷ meters from the level of the open sea in February ۲۰۲۱. Overall, ۳۵ cucumber inbred lines, available in the Germplasm Bank, University of Guilan, were selected and on completely randomized design, in three separate rows, and with three replications. A code was assigned to each of the lines in order to facilitate the naming of lines and easier evaluation. In the winter of ۲۰۱۹, the desired genotypes were first planted in the seedling tray and kept there until the second true leaves were observed. Then they were transferred to the greenhouse in the form of a completely randomized design with ۲۷ lines of inbred cucumbers, in three separate rows with ۳ replications and ۳ observations. The length of the plant breeding period continued until the economic fruiting of the plant. During the growing season, various traits were checked and recorded according to the national guidelines for tests of differentiation, uniformity and stability in cucumber prepared by the Research Institute of Registration and Certification of Seeds and Seedlings. These traits are the Fruit diameter (mm), Fruit length (mm), Fruit number, Weight of single fruit (g), Total fruit weight (g), Number of female flowers in ۱۵ nodes, Number of female flowers per node, Width of the end of the terminal leaf(cm), Length of the end of the terminal leaf(cm), Number of lateral branches in ۱۵ nodes, Length of ۱۵ internodes (cm).   Results and Discussion Genetic diversity in plant genotypes is essential for a successful breeding program. Understanding the degree of variability in plant species is of importance because it provides the basis for selection. The results of variance analysis show that there is a highly significant variation between the studied lines at the level of ۱%. The significant difference observed between genotypes for all traits indicates the existence of inherent genetic variation among genotypes. The evaluation results show that the average fruit weight trait varied from ۱۳۷۱.۷ grams (L۵۷) to ۱۵۷.۷۱ grams (L۳۵) among the examined lines. Furthermore, genotype L۵۷ (۱۱۷.۵۶ grams) had the highest statistical position in terms of single fruit weight. The results of the mean comparison table showed that L۳۴ line had the highest fruit length values (۱۶۱.۸۴ mm) and L۴۹ line had the highest fruit diameter values (۳۹.۸۳ mm). Moreover, L۵۵ and L۳۴ lines had the lowest values of fruit length (۹۲.۴۶ mm) and diameter (۲۴.۶۱ mm), respectively. The leaf area variable varied from ۴۲۶.۵۲ cm۲ (L۵۷) to ۲۰۴.۲۴ cm۲ (L۳۱) among the studied lines. The results of chlorophyll index traits investigation and total soluble solids showed that L۵۱ line had the highest values in both traits. The results of statistical analyses pertaining to genotypic and phenotypic variance, as well as general heritability, revealed that the trait with the highest heritability, at ۹۹.۴۴%, was fruit weight. With the exception of five traits-length of ۱۵ primary internodes, leaf surface, length and width of the terminal leaf, and single fruit weight-whose heritability values were ۸۷.۳۵%, ۷۳.۸۳%, ۶۳.۵۹%, ۶۱.۲۷%, and ۲۶.۲۳%, respectively, the heritability exceeded ۹۰% for the remaining traits. These findings indicate that most of the traits examined exhibited high heritability, suggesting they were less influenced by environmental factors. Factor analysis, an essential multivariate technique, was employed to explore trait relationships and assess the genetic diversity among genotypes. The results of factor analysis for ۲۷ evaluated cucumber genotypes show that eight factors were identified. They were ۲۳.۵۲, ۱۲.۶۳, ۱۱.۸۱, ۹.۹۵, ۸.۶, ۷.۳۴, ۶.۲۷, ۴.۲۱ percent. in total explained ۸۸% of the total diversity of traits in the studied population. In total, they justified ۸۸% diversity of total traits in the studied population. The results of the cluster analysis placed the studied genotypes in four different groups based on the mean of traits. To ensure the cut-point in the dendrogram and to determine the actual number of groups, the discrimination function analysis method was used. The results of discrimination function analysis showed that the success of cluster analysis in grouping genotypes was ۱۰۰%. Since the genotypes in each of the clusters have a greater genetic affinity with the genotypes in the same cluster and, conversely, a greater genetic distance with the genotypes in different clusters, hybridization can be done among the genotypes in different clusters according to the value of traits average for each cluster for more productivity of phenomena such as heterosis and transgressive segregation. On this basis, it seems that it is possible to produce hybrids that are superior to their parents in terms of various traits by hybridization between the genotypes in the first and second clusters with the genotypes in the third and fourth clusters.   Conclusion According to the results obtained from this study, L۵۷ and L۵۴ genotypes had higher values than the rest of the genotypes in terms of fruit number and total fruit weight. Also, according to the results of cluster analysis, L۵۷ line had higher total mean values in traits of total fruit weight, single fruit weight, diameter of the tail of the fruit, fruit, kernel diameter, fresh and dry weight of leaves and leaf area. In this study, the genotypes of the second and third groups in the fruit number trait, and the genotypes of the first and third groups in the fruit weight trait, due to having the maximum difference, were found suitable for use in crosses in order to create more diversity. In general, the results of this research showed that there was a suitable diversity among the studied lines in terms of all measured traits. In addition to the fact that the results obtained from this research can be used in future breeding programs, the results of multivariate statistical methods also show solutions for the scientific crossing of genotypes in future research. So that the genotypes placed in different groups in cluster analysis (Group ۱: L۵۷, Group ۲: L۵۴, L۵۲, L۴۷, L۳۲, L۴۹, and L۲۷, Group ۳: L۴۳ and L۳۵, Group ۴: L۵۹, L۵۳, L۵۱, L۳۴, L۲۶, L۵۵, L۲۵, L۳۹, L۳۱, L۳۰, L۳۳, L۲۸, L۲۹, L۳۶, L۲۴, L۴۴, L۲۲, and L۲۰) and had superior characteristics in terms of different components, can be crossed together to create recombinant genotypes.

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