Growing vegetables
Gh. Kiani; S. 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.
Jamal-Ali Olfati; Gh. Peyvast; habibolah samizadeh; B. Rabie; S.A. Khodaparast
Abstract
Partial diallel design can be used to investigate the general and specific combining ability, and heterosis. Combining ability and heterosis were studied in a 6×6 partial diallel cross to see the nature of gene action for fruit quality indices in cucumber (Cucumis sativus L.) during 2007 to 2009. Analysis ...
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Partial diallel design can be used to investigate the general and specific combining ability, and heterosis. Combining ability and heterosis were studied in a 6×6 partial diallel cross to see the nature of gene action for fruit quality indices in cucumber (Cucumis sativus L.) during 2007 to 2009. Analysis of variance revealed highly significant differences among all the F1 hybrid means and their respective six parental values for all the traits examined. The mean squares of general combining ability (GCA) and specific combining ability (SCA) were also highly significant. SCA genetic variances were greater than GCA and more important for the seedcell size, showing the additive and non-additive gene action. Fruit color was controlled by additive type of gene action due to high GCA variances. Fruit shape and overall performance were controlled additively and non-additively due to high general combining ability. Line 605 and 118 were found to be the best general combiner and its utilization produced valuable hybrids with desirable SCA F1 hybrids.
