Screening of Brassica rapa L. var. yellow sarson genotypes against downy mildew Alternaria blight

Abstract

The use of resistant varieties is considered to be the best method of disease control. Therefore, the study was carried out to find out the sources of resistance against downy mildew (caused by Peronospora brassicae (Pers. ex. Fr.)) and Alternaria blight (Alternaria brassicae (Berk.) Sacc. and Alternaria brassicicola (Schw.) Wiltshire) in Brassica rapa. The pathogen is greatly influenced by weather with the highest disease incidence in wet seasons and in areas with relatively high rainfall. A. brassicae can affect host species at all stages of growth, including seed. Symptoms of the disease are characterized by formation of spots on leaves, stem and siliquae. This investigation was conducted under three different environments in randomized block design with three replications. A total of 20 genotypes of yellow sarson were screened for varietal reactions against the diseases under field conditions during rabi 2010 and 2011. None of the genotypes was found free from both the disease, in case of downy mildew disease; only one genotype named Jagrati was found moderately resistant. For Alternaria blight, seven genotypes named, Benoy, Pusa Gold, YSK 09–1, PYS 2008–2, NRCYS-05–02, YSWB-2012 and NDYS-427 were found moderately resistant.