Growing vegetables
A. Mirhosseyni; M. Hassanpour Asil; J. A. Olfati; M. B. Farhangi
Abstract
Introduction
Cucumber (Cucumis sativus L.) is an annual plant in the Cucurbitaceae family, which has 90 genera and 750 species. Iran, with an under-cultivation area of 89,632 hectares and a production rate of 1,804,184 tons of cucumbers, yield of 201,289 tons per hectare, and it is the third largest ...
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Introduction
Cucumber (Cucumis sativus L.) is an annual plant in the Cucurbitaceae family, which has 90 genera and 750 species. Iran, with an under-cultivation area of 89,632 hectares and a production rate of 1,804,184 tons of cucumbers, yield of 201,289 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 27 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 49 degrees and 36 minutes east and latitude 37 degrees and 16 minutes north with a height of 7 meters from the level of the open sea in February 2021. Overall, 35 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 2019, 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 27 lines of inbred cucumbers, in three separate rows with 3 replications and 3 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 15 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 15 nodes, Length of 15 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 1%. 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 1371.7 grams (L57) to 157.71 grams (L35) among the examined lines. Furthermore, genotype L57 (117.56 grams) had the highest statistical position in terms of single fruit weight. The results of the mean comparison table showed that L34 line had the highest fruit length values (161.84 mm) and L49 line had the highest fruit diameter values (39.83 mm). Moreover, L55 and L34 lines had the lowest values of fruit length (92.46 mm) and diameter (24.61 mm), respectively. The leaf area variable varied from 426.52 cm2 (L57) to 204.24 cm2 (L31) among the studied lines. The results of chlorophyll index traits investigation and total soluble solids showed that L51 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 99.44%, was fruit weight. With the exception of five traits-length of 15 primary internodes, leaf surface, length and width of the terminal leaf, and single fruit weight-whose heritability values were 87.35%, 73.83%, 63.59%, 61.27%, and 26.23%, respectively, the heritability exceeded 90% 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 27 evaluated cucumber genotypes show that eight factors were identified. They were 23.52, 12.63, 11.81, 9.95, 8.6, 7.34, 6.27, 4.21 percent. in total explained 88% of the total diversity of traits in the studied population. In total, they justified 88% 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 100%. 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, L57 and L54 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, L57 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 1: L57, Group 2: L54, L52, L47, L32, L49, and L27, Group 3: L43 and L35, Group 4: L59, L53, L51, L34, L26, L55, L25, L39, L31, L30, L33, L28, L29, L36, L24, L44, L22, and L20) and had superior characteristics in terms of different components, can be crossed together to create recombinant genotypes.
Fatemeh Moradipour; Jamal-Ali Olfati; Yousef Hamidoghli; Atefeh Saburi; Bahman Zahedi
Abstract
Introduction: Cucumber (Cucumis sativus L.) is one of the most widely cultivated vegetables. Plant length is a quantitative trait is controlled by many genes. These traits are difficult to study due to the complex nature of their inheritance. The combining ability estimation is useful in determining ...
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Introduction: Cucumber (Cucumis sativus L.) is one of the most widely cultivated vegetables. Plant length is a quantitative trait is controlled by many genes. These traits are difficult to study due to the complex nature of their inheritance. The combining ability estimation is useful in determining the breeding value of cucumber lines by suggesting the appropriate use in a breeding program. In studying combining ability, the most commonly utilized experimental approach is the diallel design. General combining ability is a measure of additive genetic action; and specific combining ability (SCA) is deviation from additivity. General combining ability is a main effect and SCA is an interaction. The aim is to determine the breeding value of the cross. Heterosis has been utilized to exploit dominance variance through production of hybrids. There are reports on positive and negative heterosis in cucumber however, there are differences between reports. This research was conducted to estimate general and specific combining ability and heterosis in cucumber inbred lines and hybrids to produce hybrids with high yield and quality.
Material and Methods: In the spring of 2014, the seven parental lines and their 21 F1 hybrid were planted at the University of Guilan, in loamy sand field. Three replications were arranged in a randomized complete block design. The sandy loam soil was prepared by plowing and disking and formed into raised beds by plowed and harrow prior to plant establishment. Rows were on 1 m centers and plants were about 25 cm apart in the row. Prior to planting 150 kg·ha-1 of nitrogen from urea and 100 kg·ha-1 of phosphorous from triple superphosphate and 80 kg·ha-1 of potassium sulfate was applied. Side dressing with the same amount of nitrogen and phosphorus occurred at 50% flowering stage. Irrigation with 250 m3·ha-1, three times weekly, was begun at plant first flowering. In each replication, 12 individuals of each line or hybrid were spaced 25 cm within a row (plot) on 1 m centers. Data were collected from 12 plants per plot of each accession. Analyses of variance (ANOVA) of data were performed and where appropriate, ANOVA was followed by LSD mean comparison of trait values. For the combining ability analysis (GCA), measurements of plants within each plot were averaged, and means were used as experimental units for analysis by the computer program Diallel.
Results and Discussion: Genotypes has significant effect on all measured characteristics. The highest plant length was related to B6 line and the lowest plant length was related to A0×B6 and B12×B6 hybrids. The highest number of lateral branch was related to B10×A11, B12×A0 and Guilan while the lowest number was related to A0, B12×B6, A15×A11. The highest plant length to first fruit was related to A4×A11 hybrids and the lowest plant length to first fruit was related to B10, B12, B10×A15 and B12×A4. The mean square of general combining ability (GCA) were significant only for plant height up to the first fruit but the mean square of specific combining ability revealed significant differences for all traits that indicated the important effects of dominance genes in inheritance of traits. Plant height up to first fruit has further general combining which reflects the non-additive genes action. The highest parent and standard negative heterosis for plant length was related to B12×B6 hybrid. This hybrid also showed the highest negative heterosis for number of lateral branch. The highest high parent negative heterosis for plant length to first fruit was related to A11×A4 hybrid while the highest standard negative heterosis was related to A0×A4 hybrid and the highest positive heterosis for this trait was obtained from B10×B12 and B12×A4 hybrids.
Conclusion: Although heterosis is affected a plant length is the primary target for increasing yield in high density cultivation, the biological complexity of this trait makes it difficult to draw meaningful conclusions in order to track individual causal elements involved in heterosis. Cucumber breeders might develop determinate or indeterminate cultivars based on high GCA for certain traits. Cucumber breeders might develop cucumber cultivars with optimal vegetative growth based on high general combining ability for their traits. The results revealed B10 and A4 lines are proposed for hybrid production with optimum vegetative growth. The hybrid obtained by crossing of B12 and B6 are proposed for cultivation with high plant density.
