Investigation of resistance to Alternaria blight in Brassica spp. in Gonbad region

Alternaria blight causes severedamage to oil producing Brassica spp. in many parts of the world, so the quality and quantity of its oil is reduced. This research was performed in fall of 2010 to investigate the resistance of Brassica species to alternaria blight, including two genotypes of mustard (j-98-102/51 and Bard-1), two genotypes of oil turnip (Candle and Rainbow), three genotypes of canola (Hayola 401, Shiralee and RGS003) and an F4 generation (fourth generation of rapeseed-mustard cross). The experiment was performed as a randomized complete block design with three replications at the agricultural research station of Gonbad, Iran. For this purpose, the incidence (I) and severity (S) of disease were measured at definite time intervals from the appearance of the symptoms to harvesting time and based on these data, disease progress curves (DPCs) of epidemics were drawn. Using DPCs, AUDPC and rAUDPC were calculated. Analysis of variance showed that there were significant differences (P<0.01) between genotypes for these variables. Data mean comparison showed that genotype Candle was the most susceptible, Bard-1 and Select4 were susceptible and J-98, RGS003, Rainbow, Shiralee and Hayola 401 showed less susceptibility to Alternaria blight, respectively.