ObjectiveCyclamen is a major potted flower with significant market demand globally. It thrives in cool climates, but recent climate change has led to increased production cost and a decline in product quality. Selecting heat-tolerant C.persicum varieties is of great significance for overcoming developmental constraints in the industry. Methods Six C.persicum lines,including 'Halios 2015', 'Halios 2090', 'Fleur in Vogue', 'Yoshino (Purple-White)', 'Sierra', and 'Halios Blush', were used as test materials. Thirteen leaf structural traits, including leaf area, upper epidermis thickness, and spongy tissue thickness, were measured after the summer period. Main indexes for heat-tolerance evaluation were identified using cluster and correlation analysis. The average membership function method was then applied to comprehensively assess and rank the heat-tolerance of the C.persicum lines. Results The mean leaf area, leaf length, and leaf width of the six C.persicum lines were 39.43 cm², 6.50 cm, and 7.08 cm, respectively, with leaf area showing the highest coefficient of variation (10.97%). Anatomical analysis revealed that 'Sierra' exhibited the largest values for sieve tube diameter, tissue compactness, and palisade-spongy ratio, while 'Yoshino (Purple-White)' had the highest values for leaf thickness and upper/lower epidermis thickness. In contrast, 'Halios 2090' showed the smallest values for palisade tissue thickness and sieve tube diameter. Cluster and correlation analysis categorized the 13 leaf structural characteristic indexes into five groups, from which five key traits were identified as representative of heat tolerance: leaf thickness, palisade-spongy ratio, palisade tissue thickness, leaf area, and tissue looseness. Based on the membership function evaluation, the heat tolerance of the six C.persicum lines was ranked in descending order as follows: Sierra>'Yoshino (Purple-White)'>'Halios 2015'>'Fleur in Vogue'>'Halios Blush'>'Halios 2090'. Conclusion This study demonstrated the feasibility of using leaf structural characteristics to comprehensively evaluate heat tolerance in C.persicum. The approach provides a scientific and efficient methodology for assessing heat-tolerance, and offers valuable insights for the selection of heat-tolerant C.persicum germplasms and the breeding of new resilient varieties.
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