Identification of gray mold resistance in different rose varieties and phenotype correlation analysis

【Objective】To identify the gray mold resistance of different rose resources, and to analyze the correlation between gray mold resistance and phenotypic traits of rose, so as to provide support for evaluating the gray mold resistance of rose resources and breeding new gray-mold-resistant varieties.【Method】Taking 349 main cultivated rose varieties as the research materials, the resistance of different rose varieties to gray mold was identified by petal inoculation and resistance evaluation of 349 rose varieties was conduct according to the natural incidence of gray mold in the field in 2019 and 2020. Five phenotypic traits including flower color, flower diameter, number of prickle thorns, floral fragrance and number of petals were investigated in 349 rose materials to carry out correlation analysis on rose gray mold resistance and phenotypic traits, and cluster analysis of the gray-mold-resistant varieties were conducted.【Result】Based on the results of two-year field investigation and petal inoculation, it was found that the disease resistance of different rose varieties was quite different, and no variety was completely immune to gray mold in the tested materials, and most of the varieties were susceptible. The resistance of the inoculated ones was different that field investigation:among the 349 varieties, the results of 187 varieties from both the artificial inoculation and field investigation was consistent, accounting for 53.58%, and they were 8 varieties such as Love, Madame Figaro, Perdita were with high resistance, and the average area of the disease lesion was 22.9 mm², and the disease index(DI) was below 15.6. There was no significant correlation between the gray mold disease index of rose resources and flower color, flower diameter, number of petals, and floral fragrance (P>0.05), but a significant negative correlation with the number of prickle thorns(P<0.05);cluster analysis showed that 107 high-resistant varieties were divided into 4 major groups, and the varieties in group Ⅰ and group Ⅱ were potential for application because of their high resistance, large and full flowers.【Conclusion】The resistance of rose to gray mold is negatively correlated with the amount of stem bark. Most of the tested rose resources are susceptible to gray mold. Through a combination of field investigation and pathogen inoculation, 8 varieties with high resistance to gray mold, Scarlet queen Elizabeth, Black Bark, Golden starlight, Jumei, Madame Figaro, Perdita, Love and glory, were selected, which will be an important support for breeding new varieties with high resistance.