نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه علوم زراعی و اصلاح نباتات، دانشکدگان ابوریحان، دانشگاه تهران، پاکدشت، ایران.
2 گروه علوم باغبانی، دانشکدگان ابوریحان، دانشگاه تهران، پاکدشت، ایران
3 گروه علوم زراعی و اصلاح نباتات - دانشکدگان ابوریحان- دانشگاه تهران، پاکدشت، ایران.
چکیده
کلیدواژه‌ها
عنوان مقاله [English]
نویسندگان [English]
This study aimed to evaluate the yield and its components as well as fruit quality traits of 650 tomato inbred lines resulting from self-fertilization of commercial cultivars. The lines were evaluated along with four commercial hybrid control cultivars in 2022 as augmented in a randomized complete block design. The coefficients of phenotypic variation and the maximum and minimum values of the studied traits showed that there was a high variation for the traits of Sunscald (%), persistent calyx in fruits (%), shelf life, titratable acidity (TA), the number of fruits per plant, single-plant yield and the number of fruit locules among the lines, so it is possible to select the best lines with high efficiency for breeding purposes. Among the lines, “242”, “495”, “17” and “85” were superior to other lines and control cultivars with a yield of over 6 kg per plant. Sunscald (%), persistent calyx in fruits (%) and the number of locules were least influenced by the environment and had the highest genetic variance. Also, principal component analysis based on morphological traits showed that the first six main components explained 69.32% of the total phenotypic variation. Stepwise regression analysis showed that number of fruit per plant and single fruit weight explained 96% of the single-plant yield variation. Overall, among the morphological characteristics, the traits of the number of fruits per plant, single fruit weight, number of inflorescences per plant, and number of fruits per inflorescence are more important indicators for selecting high-yielding tomato lines.
کلیدواژه‌ها [English]
Extended Abstract
Introduction
Tomato (Solanum lycopersicum L.) is one of the most widely grown vegetables in the world, with special importance due to its large consumption and high health and nutritional values, both for fresh and processing markets. Approximately 182.2 million tons of tomato is produced worldwide on more than 5.7 million hectares. Currently, this vegetable accounts for 25% of total vegetable production in the world. Traditional breeding methods have yielded varieties with notable performance traits. Given the increasing population demands in the world, especially Asia, high productivity remains the primary goal of tomato improvement programs. Fundamental fruit performance traits include fruit weight, fruit number per plant and fruit set efficiency (the ratio of flowers which are setting fruits). Moreover, fruit quality significantly affects consumer preference and determines the final product price. This study focuses on exploring the relationship among yield, its components and fruit quality traits in tomato lines, given the need for genetic diversity enhancement and utilization in tomato breeding programs.
Materials and methods
In this study 650 tomato lines of tomato were compared in terms of yield, fruit quality and morphological traits. In addition, the heritability of various traits was assessed. The experiment was conducted at College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran, in spring and summer of 2022. Plant materials included 650 lines from the sixth generation resulting from self-pollination of commercial hybrid varieties, along with four control cultivar; Bedero, Brivio, 8320, and Matin. Morphological measurements aimed to assess diversity for various agricultural traits, including fruit and plant appearance. Seeds were germinated in trays in a greenhouse with controlled conditions and then transplanted to the field. Evaluation was performed in augmented with randomized complete block design. Among 650 tomato lines, 164 were selected based on resistance to viruses, fungi, and pests, plant uniformity, fruit shape, firmness, taste, and other fruit quality traits. Various traits related to plant architecture, fruit yield and quality were measured throughout the growing season, including number of inflorescences per plant, number of flowers per inflorescence, number of fruits per inflorescence, Sunscald (%), persistent calyx in fruits (%), fruit length, fruit width, pricarp thickness, number of locules, pH, titratable acidity, Brix degree, shelf life, fruit number per plant, single plant yield, single fruit weight and days to harvest. Statistical analyses included variance analysis and calculation of descriptive statistics and heritability for all traits. Principal component analysis, cluster analysis, and biplot were carried out for data reduction and visualization.
Results and Discussion
The results of variance analysis showed that there were significant difference among control cultivars for all traits except shelf life, days to harvest, TA, Brix, and pH. The range of single-plant yield variation was very high among 164 lines, ranging from 1.21 to 6.43 kilograms per plant. Estimation of variance components indicated that among the studied traits, single-plant yield and days to harvest were more influenced by the environment, as they showed low genetic variance values. Conversely, sunscald (%), persistent calyx in fruits (%), and number of locules were less influenced by the environment as showed the highest genetic variance. The highest coefficients of genotypic and phenotypic diversity were attributed to sunscald (%), persistent calyx in fruits (%), TA, and number of locules, respectively. The existing correlation coefficients between traits showed that the number of fruit per plant (0.730), pricarp thickness (0.409), number of inflorescences per plant (0.382), single fruit weight (0.248), and number of locules (0.223) had significant positive correlations at the 1% level with single-plant yield. Stepwise regression analysis showed that number of fruit per plant and single fruit weight explained 96% of the single-plant yield variation. Based on cluster analysis, the studied tomato lines were divided into three groups. The first group was the largest cluster, comprising 64 lines (41.5%). This cluster, with above-average value for single-plant yield, consisted of highly productive lines. Principal component analysis results showed that only the first two components in PCA had eigen values higher than 1, indicating a cumulative variance of 67.36%.
Based on the results of the present study, single-plant yield, number of inflorescences per plant, number of flowers per inflorescence, number of fruits per inflorescence, number of fruits per plant, and single fruit weight are important for improving the morphological and qualitative traits of tomato fruit. Therefore, these traits can be utilized for parent selection in hybridization programs aimed at broadening the genetic base in the population and also for the development of F1 hybrids.
Conclusion
In this study, 164 tomato lines were examined based on morphological traits. The results of variance analysis indicated the high genetic diversity among the evaluated lines, and these results can be beneficial for improving the measured agronomic traits. On the other hand, the measured traits in this study also showed good potential for investigating genetic diversity within the studied population.
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