Abstract:

【Objective】To identify the characteristics of rust pathogens in Hemerocallis citrina and the rust resistance of different Hemerocallis citrina varieties.【Methods】32 Hemerocallis citrina rust samples were collected from Hunan Province，Gansu Province，Shaanxi Province and Jiangsu Province. The uredinium and urediniospores of Hemerocallis citrina were observed and measured under microscope. One of the Hemerocallis citrina rust sample（yx-30）was then selected and the telia and teliospores were observed and measured. The rust resistance of 50 samples of Hemerocallis citrina germplasm resources to strain yx-26 was identified by artificial inoculation.【Results】The uredinium of Hemerocallis citrina rust samples were mostly on the abaxial side of leaves，forming orange or yellow-brown spots with diameters of 0.28-1.96 mm. The urediniospores were almost spherical or oval，yellow and unicellular and 16.0 to 21.5 μm by 17.2 to 32.4 μm in size. The wall thickness was 1 to 3 μm. The telia of Hemerocallis citrina rust sample was dark brown and flocculent. The teliospores were oval，rod-shaped，yellow，bicellular，with constriction in the middle，and shaped like gourd. The size was 68.0 to 81.0 μm by 19.4 to 22.2 μm. The length of sporocyst stalk was 11 to 16 μm. The rust resistance to yx-26 strain of the 50 Hemerocallis citrina germplasm resources were 11 cultivars with high resistance，21 cultivars with moderate resistance，8 cultivars susceptible，and 10 cultivars highly susceptible.【Conclusion】The morphological characteristics of uredinium of Hemerocallis citrina were similar，while the morphological sizes of urediniospores were slightly different. The telia of Hemerocallis citrina rust sample was dark brown and flocculent. The teliospores were yellow，bicellular and shaped like gourd. The rust-resistant varieties accounted for 3/5 of the 50 samples of Hemerocallis citrina germplasm resources，which could provide reference for the planting of rust resistant varieties of Hemerocallis citrina in different regions.

Key words: Hemerocallis citrina, Rust, Rust pathogen, Rust resistance