A digital image analysis system (DIAS) for assessment of bioassays on Rhododendron simsii against Cylindrocladium scoparium .

摘要

Cylindrocladium scoparium is one of the most important fungal pathogens of Rhododendron simsii. Successful breeding for resistance to this disease needs sensitive, practicable and reproducible screening methods. Preliminary results of a research project aimed at developing effective screening methods for evaluation of plant resources for Cylindrocladium resistance in R. simsii are presented. Bioassays with detached leaves and shoots were established. Development of disease symptoms could be quantified with a digital image analysis system. Therefore all samples were photographed by a digital camera under defined illumination conditions before inoculation and at different measurement time points after inoculation. Eighty-six Rhododendron genotypes (64 R. simsii varieties and 22 Rhododendron species) were screened in the bioassays for C. scoparium. The responses of the genotypes to C. scoparium were estimated by symptom scoring with the digital image analysis system. The analyses of the disease symptoms showed significant differences regarding the susceptibility to the fungal pathogen and disease progress. Tolerant genotypes could be distinguished from highly susceptible genotypes. However, true resistance was not observed within the screened gene pool.