نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه علوم و مهندسی باغبانی و فضای سبز، دانشکده کشاورزی، د انشگاه تهران، کرج، ایران
2 گروه علوم باغبانی، دانشکده کشاورزی دانشگاه تهران، کرج، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
This study was conducted to evaluate the phenotypic diversity among 39 tomato genotypes (Solanum lycopersicum L.). The plant materials included a range of both local and commercial cultivars that were examined to identify valuable traits for breeding and crop improvement. The experiment was carried out under field conditions using a randomized complete block design (RCBD) with three replications. The evaluated traits encompassed morphological characteristics (such as fruit shape and size), physical attributes (firmness and density), chemical properties (pH, titratable acidity, TSS, and TSS/TA ratio), as well as descriptive traits such as fruit color, pericarp thickness, and number of locules. The results of analysis of variance and Duncan’s multiple range test revealed significant differences among genotypes at the 1% probability level. Traits such as total fruit weight per plant, number of fruits, fruit firmness, and TSS/TA ratio showed the greatest variation among the genotypes. To identify phenotypic clustering patterns, hierarchical cluster analysis using Ward’s method was also performed, resulting in distinct genotype groupings. The findings of this study can serve as a valuable basis for selecting superior parental lines of tomato in breeding programs aimed at enhancing yield, fruit quality, and developing cultivars adapted to various production goals and market demands.
کلیدواژهها [English]
Extended Abstract
Introduction
Tomato is one of the most important horticultural crops worldwide due to its high nutritional value and wide applicability in the food industry. As a self-pollinated, day-neutral plant cultivated extensively in tropical and temperate regions, tomato holds significant potential in breeding programs thanks to its broad genetic diversity. Morphological, physical, and chemical traits such as fruit weight, firmness, color, flavor, and nutritional composition directly influence market value and product quality. In the context of growing population, limited agricultural land, and increasing demand for higher-quality produce, the development of improved tomato cultivars requires a focus beyond yield alone. In this regard, precise characterization and evaluation of phenotypic diversity among genotypes are essential steps toward selecting superior parental lines and advancing cultivar development. Genetic diversity is commonly analyzed through morphological, biochemical, or molecular markers, which provide insight into genotype performance under diverse production and market conditions. Morphological characterization, in particular, remains a foundational and widely used method for identifying genetic differences, often involving field trials and detailed trait evaluation. Systematic phenotypic assessments not only contribute to understanding population structure but also guide targeted breeding decisions. Continued research in this field is critical for optimizing selection strategies, enhancing fruit quality, and meeting the evolving needs of both producers and consumers.
Materials and Method
This study was conducted as a field experiment under open-field conditions from 2018 to 2021. A total of 62 tomato seed samples were collected from various sources, including local, commercial cultivars, and gene bank accessions originating from Sarab, Razliq, Mamaghan, and Tabas regions (Iran). In 2021, 39 genotypes were selected for final evaluation. The genotypes were cultivated based on a randomized complete block design (RCBD) with three replications. Each plot contained 20 plants arranged in two rows, with 50 cm spacing between plants on the row. Evaluations included morphological traits (fruit color, length and width, pericarp and locule thickness, longitudinal and cross-sectional shape, tip shape, and blossom-end depth and bulging), physical traits (fruit volume, density, firmness, mean and total weight of 10 fruits, average fruit weight and fruit number per plant), and chemical traits (pH, total soluble solids [TSS], titratable acidity [TA], and TSS/TA ratio). TSS was measured using a refractometer. TA was determined by titration with 0.1N NaOH in the presence of phenolphthalein as an indicator. Fruit firmness was assessed using a handheld penetrometer, pH was measured with a digital pH meter, and fruit density was calculated by dividing the fruit's weight by its volume, which was determined through water displacement. All data were recorded at the physiological maturity stage on a per-plant basis.
Results and Discussion
The results of this study revealed significant genetic diversity among the tomato genotypes in terms of physical, chemical, and mechanical traits. This diversity can play an important role in breeding programs and in selecting suitable cultivars for specific purposes. The Mamaqan genotype showed high values in all three color components (*L, *a, *b), indicating a bright red to yellowish hue. Additionally, genotype TN-957 exhibited superior redness compared to others. Among mechanical characteristics, genotypes like King Stone, due to their desirable firmness, are recommended for transportation. Genotypes such as Cuor Di Bue, TN-941, and Super Urbana, because of their higher fruit weight and volume, are more suitable for fresh consumption, while TN-906, with its higher fruit yield per plant, is ideal for improving field productivity. Chemical traits such as acidity, total soluble solids (TSS), and the TSS/TA ratio have a significant impact on taste, shelf life, and market acceptance. Genotypes like TN-944 and Aghmiyon have a well-balanced flavor and are ideal for fresh consumption, while genotypes such as Super Urbana and Super Major, due to their higher acidity and lower TSS, are more appropriate for processing products like tomato paste. In terms of morphology, genotypes with larger size and appropriate skin thickness, like Cour di Boe and TN-1089, are considered more marketable. In contrast, smaller genotypes such as Torsh Riz-e-Tabas or TN-941 are better suited for specific cultivation purposes. Furthermore, the number of locules in a tomato fruit can significantly affect the internal tissue quality and its suitability for processing. Overall, the high phenotypic diversity observed in this germplasm highlights its valuable potential for breeding, production, and commercial applications.
Conclusions
The results of this study indicate a remarkable genetic diversity among the evaluated tomato genotypes in terms of morphological, physical, and chemical characteristics. The wide variations observed in these traits suggest a high potential for targeted selection in breeding programs. Some genotypes, with features such as firmness, desirable color, good yield, or marketable appearance, are suitable for various production pathways. Moreover, traits like acidity, soluble solids, and the TSS/TA ratio play significant roles in the quality and shelf life of the product. The combination of these traits can facilitate the selection of optimal genotypes for specific applications. The observed diversity highlights that identifying and utilizing these genotypes can lead to improved quality, increased yield, and the development of products tailored to market demands.
Author Contributions
Data Availability Statement
Data available on request from the authors.
Acknowledgements
The authors would like to thank the research council of the University of Tehran, Iran for the financial support of this research.
Ethical considerations
The authors avoided data fabrication, falsification, plagiarism, and misconduct.
Conflict of interest
The author declares no conflict of interest.
)