Screening of Rapeseed Genotypes against Alternaria Leaf Blight Resistance at Nawalpur, Sarlahi

Abstract

: Rapeseed is major oilseed crop of Nepal but its yield is limited due to various factors and one of the major limiting factors is leaf blight disease caused by Alternaria brassicae (Berk.). An experiment was conducted at Oilseed research Program, Nawalpur, Sarlahi, Nepal during two consecutive years viz. 2019 and 2020 to screen the rapeseed genotypes against alternaria leaf blight disease. The research was conducted in augments design with each genotype sown in two rows of 3 m length 30 cm apart and disease was allowed to develop naturally in the field. Four times scoring of disease was done starting from 49 days after sowing at seven days interval. Out of one hundred and ninety genotypes used in evaluation, there were no genotypes that were immune or completely resistant to the disease but thirty one genotypes during 2019 and eight genotypes during 2020 were found to be moderately resistant to the disease. One genotype ICT 2010-7 was found to be moderately susceptible in both the years’ observations. Area under disease progress curve (AUDPC) value for three genotypes (ICT 2001-6, ICT 2001-7, and ICT 2010-9) during 2019 and six genotypes (ICT 2010-7, S R O 2, ICT 2004-1, NGRC 2798, ICT 2004-42, and ICT 2006-3) during 2020 was lower (<400) representing lower disease progress. Hence the genotypes that were moderately resistant as well as have lower AUDPC value can be utilized in future by plant breeders and plant pathologist for development of tolerant varieties as durable resource for disease management.