Document Type : Research Paper
Authors
1
Seed and Plant Certification and Registration Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
2
Cotton Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Gorgan, Iran
10.22092/ijcr.2026.372145.1254
Abstract
Background and objectives: Verticillium wilt is one of the most destructive diseases of cotton, causing significant reductions in yield and fiber quality. Due to the long-term survival of the pathogen in soil, its control is challenging, and the use of tolerant cultivars is considered the most effective management strategy. This study aimed to evaluate the susceptibility of different cotton cultivars to Verticillium wilt and to identify relatively resistant cultivars using agronomic and biochemical indicators.
Materials and methods: This research was conducted both field and greenhouse conditions. In the field, eight cotton cultivars, including six introduced cultivars (May558, Sumer, Milet84, Yildirim63, Ramses, and BA911) and two local cultivars including Golestan (relatively tolerant) and Varamin (susceptible) were grown at the Karkandeh research station under natural infection by soil-borne fungi. The experiment was arranged in a randomized complete block design with three replications, and agronomic traits and yield components were evaluated. Soil populations of the pathogen were measured, and at the end of the vegetative growth stage, fungal isolates were obtained from the stems of different cultivars. The isolates were first identified based on morphological characteristics and molecular analyses, and their pathogenicity was evaluated. The isolate exhibiting the highest disease severity was selected for greenhouse experiments. In the greenhouse, seedlings of different cultivars were artificially inoculated with the selected fungal isolate, and after 40 days, disease incidence and index, growth traits, defense enzyme activities including polyphenol oxidase and phenylalanine ammonia-lyase, lignin deposition, and total phenolic content were measured.
Results: The causal fungus was identified as Verticillium dahliae based on a combination of morphological characteristics and molecular analyses using species-specific primers, confirming it as the primary pathogen in isolates obtained from soil and stems of different cotton cultivars. Pathogenicity tests showed that all isolates were capable of inducing disease symptoms of varying severity in Varamin seedlings. Significant differences were observed among the cultivars in disease incidence and severity, agronomic traits, and biochemical responses. Varamin exhibited the highest susceptibility, whereas BA911 showed the lowest disease incidence and severity under both greenhouse and field conditions. Fungal inoculation significantly reduced growth traits in all cultivars, although the reduction was less pronounced in BA911, Yildirim63, and MY558. Activities of polyphenol oxidase and phenylalanine ammonia-lyase, lignin content, and phenolic accumulation increased more rapidly and to higher levels in BA911, Milet84, Yildirim63, Sumer, and May558 compared to the relatively tolerant Golestan and susceptible Varamin and Ramses cultivars.
Conclusion: Based on the results of this study, BA911 was identified as a relatively resistant cultivar to Verticillium wilt. The combined use of biochemical indicators and agronomic traits provides an effective tool for assessing the susceptibility of cotton cultivars and can be applied in breeding programs and sustainable disease management strategies.
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