Resistance in Cucumis sativus Germplasm to Causal Agents of Powdery Mildew and Downy Mildew

In order to establish cucumber genotypes resistant to powdery mildew and downy mildew it was tested 94 accessions supplied from Center for Genetic Resources, The Netherlands (CGN). The trials were carried out during 2004-2007 under glasshouse and plastichouse conditions. Resistant reaction to powdery mildew (Sphaerotheca fuliginea Poll.) was observed in 28 accessions and to downy mildew (Pseudoperonospora cubensis (Berk & Curt.) Rostow) in 16 accessions that possess different fruit type. Three pickling (W 1922, LV 41, Sumter) and eight salad genotypes (Santo, Long Green, Stono, Polaris S, Sc50, Sagami Hanjioro, Poinset DPM, Taichong Mou Gua) responded with combine resistance to both pathogens. Cucumber germplasm was characterized by type of flowering and fruit morphology. The three groups of accessions can be used in breeding program to develop resistant cultivars. Cluster analysis shows that accessions contain in the first cluster (resistant to powdery mildew and downy mildew) are the most adequate to be parent components for producing new hybrids and inbred lines. Hybrid combinations have to involve parent components that both inbred lines should be resistant to both pathogens.