Growing vegetables
Ghaffar Kiani; Sasan Golcheshmeh
Abstract
Introduction
Tomato is a self-pollinated crop and has a high potential for heterosis production. Tomato has a wide range of diversity in terms of vegetative and fruit traits. Therefore, learning information about the genetics of the tomato plant and the inheritance of its various traits to the next ...
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Introduction
Tomato is a self-pollinated crop and has a high potential for heterosis production. Tomato has a wide range of diversity in terms of vegetative and fruit traits. Therefore, learning information about the genetics of the tomato plant and the inheritance of its various traits to the next generation will help plant breeders to use appropriate breeding methods to improve them. One of the methods that is used to know the genetic structure of plants, identify parental lines and determine their combining ability is line × tester analysis. Line × tester analysis provides information about general and specific combining of parents and can be useful in estimating different types of gene effects such as additive and non-additive effects. In most of the developed countries, many researches have been done in relation to hybrid production and combining ability among tomato lines, and sometimes the inferred results are different from each other. In Iran, few studies have been done about crossing cultivars and their hybrids, and most of the seeds used by farmers are imported from other countries. Therefore, this study intends to evaluate genetic variance components, general and specific combining ability of some quantitative traits in a number of tomato lines and testers and their hybrids by using line × tester analysis.
Materials and Methods
This research was conducted in Sari Agricultural Sciences and Natural Resources University, Mazandaran Province, Iran in 2022. Two modified cultivars SC and V as lines and three modified cultivars L, R and MZ as testers were crossed with each other to create F1 hybrids. Six F1 genotypes and their parents (11 treatments in total) were cultivated in the farm in a randomized complete block design with three replications. The evaluated traits included the number of days to the first flowering, earliness, number of fruits per plant, fruit weight per plant (g), fruit yield (g), fruit length and width (cm). In order to analyze the variance of the experimental design to search for diversity between treatments, to separate the effects of treatments into their components based on line × tester analysis, to mean comparison with Duncan's test, and also to calculate the general and specific combining ability, R statistical software was used. Also, in order to calculate additive and non-additive variances, Singh and Chaudhary's method was used.
Results and Discussion
The results of line × tester variance analysis showed that the mean squares of parents and testers were significant for all traits except fruit length and width, and the mean squares of crosses and lines were significant for all traits except fruit length. The effect of line × tester was significant for all traits except the number of fruits per plant and fruit length. The line of SC to improve the number of days to first flowering, earliness, plant height, fruit weight per plant, and fruit width, and the line of V to improve the number of fruit per plant were the best general combiners with testers. The tester of L for improve all traits except yield, and the tester of MZ for improve plant height were the best general combiners with the maternal lines. Among the crosses, the SC×L cross for improve earliness and fruit width, and the SC×R and V×MZ crosses for improve plant height and fruit weight per plant, respectively, were favorable specific combiners. The mean comparison of the genotypes for some important traits showed that among the parental cultivars, the line of SC and among the crosses, the SC×L genotype had the lowest means for the number of days to first flowering and earliness. Also, the line of SC for the number of fruits per plant and the SC×L genotype for fruit weight per plant, yield and fruit width had the highest means. Also, the estimation of additive and non-additive variances indicated that in plant height and fruit weight per plant traits, additive variance plays the main role. While for the traits of the number of days to first flowering, earliness and yield, the contribution of non-additive variance was more than the additive variance.
Conclusion
According to the results obtained from this study, in future projects it is recommended to use parents that have significant general combining ability (GCA) for traits. Because such parents easily transfer the trait to their next generation. In this way, the line of SC was a good general combiner for the number of days to first flowering, earliness, plant height, fruit weight per plant and fruit width, and the line of V was a good general combiner for the number of fruits per plant. Among the testers, the tester of L was a good general combiner for improve the number of days to first flowering, earliness, number of fruits per plant, fruit weight per plant, and fruit width, and the tester of MZ recorded a high GCA for the plant height. Also, for the improvement of earliness and fruit width, the SC×L cross and for plant height and fruit weight per plant, SC×R and V×MZ crosses were favorable specific combiner. Mean comparison of genotypes showed that the SC×L cross is superior to its parents for the number of days to first flowering, earliness, fruit weight per plant, fruit yield, and fruit length and width. The traits of plant height and fruit weight per plant are more affected by additive variance, so the best breeding method to improve plant height and fruit weight per plant is selection from among the segregating population. The traits of number of days to first flowering, earliness and yield were affected by non-additive variance, so hybrid production is recommended to improve the mentioned traits.
Growing vegetables
Sasan Golcheshmeh; Ghaffar Kiani; Seyyed Kamal Kazemitabar; Saeid Navabpour
Abstract
Introduction
Tomato is a product with a wide range of genotypes with different yields and selection based on this trait and its components can accelerate the breeding programs of this plant. The most important goals of tomato breeders have been to increase yield, disease resistance, early maturity, ...
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Introduction
Tomato is a product with a wide range of genotypes with different yields and selection based on this trait and its components can accelerate the breeding programs of this plant. The most important goals of tomato breeders have been to increase yield, disease resistance, early maturity, and improve the quality characteristics of the fruit. Therefore, awareness of genetic diversity in the population is an important step in plant breeding, and to achieve this goal, the studied genotypes must first be identified in terms of genetic potential and favorable agronomic traits. The usual approach for describing and evaluating populations requires cultivating sample populations and evaluating their morphological and agronomic characteristics. In this regard, multivariate statistical methods play an important role in studying genetic diversity and selecting appropriate parents. Unfortunately, the tomato cultivars used in Iran are often not at the favorable level in terms of important traits such as the number of days to fruit ripening, fruit weight, fruit yield, fruit length, and width, and few studies have been done on these traits. Therefore, this study was conducted to investigate the morphological diversity, evaluate the yield and its components among some imported tomato lines using analysis of variance, cluster analysis, and principal component analysis.
Materials and Methods
This study was performed in Sari University of Agricultural Sciences and Natural Resources, Mazandaran, Iran in 2020. The plant material included 24 tomato lines imported from the Canadian Plant Gene Bank and one check variety. The experimental design used for morphological analysis was a randomized complete block design with three replications. Evaluated characteristics were included of the number of days to first flowering, number of days from germination to first fruit coloring (early ripening), plant height (cm), number of fruits per plant, average fruit weight per plant (g), plant yield (g), length and width of the fruit (cm). After measuring the characteristics at the farm and recording the data, analysis of variance was performed to examine the diversity between lines in terms of the studied variables, and Duncan test was used to compare the means and SAS software was used to test the correlation coefficients of the variables. Cluster analysis for grouping of tomato lines was performed based on the mean of the main data of standardized traits, which was determined by Euclidean distance to determine the distance between the lines, and the UPGMA method was used to merge the clusters. Principal component analysis was performed based on the mean of the main data of morphological traits.
Results and Discussion
The results of the analysis of variance showed that there was a significant difference between all lines in terms of the studied characters. Also, principal component analysis based on morphological traits showed that the first two main components accounted for 75% of the total phenotypic variation in the data and the number of days from germination to first fruit coloring (-0.606), the number of days to first flowering (-0.516), fruit weight per plant (0.492), fruit width (0.480), fruit length (0.472), plant height (-0.445), fruit yield per plant (0.395) and the number of fruits per plant (-0.367) had the highest contribution in yield changes. Therefore, these variables might be taken into consideration for effective selection of parents for hybridization programs for broadening the genetic base in the population as well as to develop elite lines or F1 hybrids. UPGMA cluster analysis also divided the studied lines into nine groups. Group IX lines were in good condition in terms of yield traits and components, group VIII lines in terms of maturity and flowering, and group IV lines in terms of fruit number per plant. And the lines in groups I and V were in moderate condition for all traits. According to these results, the cross of the lines in the more distant groups can produce hybrids with high diversity and maximum heterosis.
Conclusion
According to the main purpose of this study, which was to evaluate the yield and its components and according to the analysis performed, lines 8, 11, and 17 due to showing the least number of days to flowering and early, lines 10 and 14 due to having the highest yield, the highest fruit weight, and highest fruit length and width and lines 2, 9, 15, 21, and 24 due to having the highest number of fruits per plant and the favorable height are also recommended for use in tomato breeding programs.
