نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه زیست شناسی، دانشکده علوم پایه، موسسه آموزش عالی نقش جهان، اصفهان، ایران
2 گروه زیست شناسی، دانشکده علوم پایه، دانشگاه شهرکرد، شهرکرد، ایران
3 بخش تحقیقات گیاهپزشکی، مرکز تحقیقات کشاورزی و منابع طبیعی اصفهان، ایران
4 گروه آموزش زیست شناسی، دانشگاه فرهنگیان، تهران، ایران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
The onion plant (Allium cepa L.), as one of the most strategic crops in the global food industry and the second most consumed vegetable after tomato, holds a significant position in agricultural economics. Due to its bioactive compounds such as flavonoids and phenolic compounds, it possesses extensive medicinal properties, including anti-diabetic, antimicrobial, and cardiovascular protective effects, in addition to its nutritional value. However, onion production faces serious biotic challenges, among which soil-borne diseases particularly basal rot caused by the fungus Fusarium represent the most critical threat to onion fields due to its long-term persistence in the soil and severe yield reduction. Given the limitations of chemical control, identifying resistant genotypes is the most sustainable strategy to address this crisis. Therefore, this research was designed to evaluate genetic diversity and identify genotypes tolerant to biotic stresses (specifically Fusarium) among Iranian landraces and commercial onion populations. To this end, ten genotypes comprising eight Iranian landraces and two international cultivars were investigated under both field and greenhouse conditions using a Randomized Complete Block Design (RCBD). Assessments were conducted based on changes in morphological indices and seed yield components in response to pathogen inoculation. Morphological evaluations revealed significant differences among cultivars regarding growth indices and resistance levels. Based on the findings, Fusarium infection led to a significant reduction in leaf number, leaf length, and stalk number in susceptible cultivars. Furthermore, correlation analyses demonstrated that morphological traits, such as leaf number and stalk length, have a direct relationship with seed yield and can serve as selection indices in breeding programs to introduce resistant and high-quality cultivars to farmers. Overall, the results of this study demonstrated that the response of indigenous landraces (such as 'Ghermez-e-Azarshahr') to the pathogen was more favorable compared to commercial cultivars, exhibiting higher stability in morphological indices.
کلیدواژهها [English]
Extended Abstract
Introduction
The onion (Allium cepa L.) is one of the most widely cultivated and consumed vegetable crops globally, holding a pivotal position in both the agricultural sector and the human diet due to its extensive nutritional and medicinal properties. Historically, onions have been utilized not only as a food flavoring agent but also as a therapeutic remedy in traditional medicine systems. Modern scientific research has validated many of these traditional uses, confirming that onions are rich in bioactive compounds such as flavonoids (particularly quercetin), organosulfur compounds, and phenolic acids. These constituents confer significant antioxidant, anti-inflammatory, antimicrobial, anticoagulant, and anti-allergic properties to the plant. Consequently, regular consumption of onions is associated with a reduced risk of various chronic conditions, including cardiovascular diseases, diabetes, renal disorders, and arthritis. Despite its immense value, onion production is severely constrained by a myriad of biotic and abiotic stressors. Among the biotic factors, fungal diseases pose a critical threat to yield stability and quality. Specifically, Fusarium root and basal plate rot disease, caused primarily by Fusarium oxysporum f. sp. cepae, are devastating soil-borne pathogens that affect the bulb during the growing season and storage, leading to significant economic losses. These diseases are notoriously difficult to manage because chemical control methods are often ineffective and environmentally unsustainable. Therefore, the development of resistant varieties through the screening and selection of superior genotypes represents the most efficient and eco-friendly strategy to combat these pathogens. Identifying genotypes with desirable morphological traits and genetic resistance is essential for ensuring sustainable onion production and food security.
Methods
To address the challenges posed by Fusarium-related diseases and to identify superior genetic material for cultivation, a comprehensive study was conducted on 10 distinct genotypes of edible onion (Allium cepa L.). The research methodology focused on a detailed morphological characterization of these genotypes alongside an assessment of their resistance to Fusarium root and basal plate rot disease. The experiment was designed to evaluate the growth patterns, yield components, and disease incidence under controlled environmental conditions. The selected genotypes were cultivated in a randomized arrangement to minimize environmental bias. Throughout the growth cycle, key morphological parameters—such as plant height, leaf number, leaf length, bulb diameter, bulb weight, and neck thickness—were meticulously recorded and analyzed. Furthermore, to evaluate disease resistance, the plants were subjected to pathogen inoculation or were monitored in conditions conducive to disease development. The severity of Fusarium root and basal plate rot disease symptoms was scored using standardized disease rating scales. Data collected from both morphological assessments and disease screenings were subjected to statistical analysis to determine significant differences among the genotypes and to correlate morphological traits with disease resistance levels.
Results
The analysis of the data revealed significant morphological diversity among the 10 evaluated onion genotypes. The study demonstrated that genotypes varied considerably in their vegetative growth characteristics, bulb morphology, and overall yield potential. Certain genotypes exhibited robust vegetative growth, characterized by vigorous root systems and extensive leaf area, which are often correlated with higher photosynthetic capacity and bulb yield. In terms of disease resistance, the screening against Fusarium root and basal plate rot disease showed a spectrum of responses among the genotypes. While some genotypes displayed high susceptibility to Fusarium infection, manifesting severe rotting at the root and neck regions and subsequent yield reduction, others showed moderate to high levels of tolerance. The resistant genotypes maintained better bulb integrity and lower disease severity scores even under pathogen pressure. Importantly, the results indicated a potential correlation between specific morphological traits—such as neck thickness and root structure—and the degree of disease resistance. The yield analysis confirmed that genotypes combining favorable morphological features with disease resistance produced the highest marketable yields compared to susceptible ones.
Conclusion
This study underscores the critical importance of genetic diversity in onion breeding programs aimed at improving yield and disease resistance. The successful identification of morphological variations and differential responses to Fusarium root and basal plate rot disease among the 10 genotypes provides valuable genetic resources for future cultivation. The findings suggest that selecting genotypes with specific morphological traits can serve as a practical indicator for breeding disease-resistant varieties. For farmers and agricultural stakeholders, the adoption of the identified superior genotypes offers a sustainable solution to mitigate the impact of fungal diseases, thereby reducing reliance on chemical fungicides and lowering production costs. Ultimately, the cultivation of these high-yielding, disease-resistant onion genotypes will contribute significantly to enhancing the productivity and quality of onions in the country, ensuring better economic returns for growers and a more stable supply of this essential crop for consumers.
“Conceptualization, M.N-E., methodology, M.N-E., software, M.HK; validation, M.N-E, formal analysis, N.A.; investigation, N.A.; resources, S.A, writing—original draft preparation, S.A.
All authors have read and agreed to the published version of the manuscript.” Please turn to the CRediT taxonomy for the term explanation. Authorship must be limited to those who have contributed substantially to the work re-ported.
The data generated and analyzed during this study are included in this published article and its supplementary information files.
The authors would like to thank all participants of the present study.
The authors avoided data fabrication, falsification, plagiarism, and misconduct.
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