Pathogenicity of different populations of the sugar beet cyst nematode (Heterodera schachtii) on sugar beet genotypes

The aim of this research was to compare the pathogenicity andsome biological and morphological characters of four populations of the sugar beet cyst nematode Heterodera schachtii, collected from infested farms of Isfahan, Shiraz, West Azerbaijan and Khorasan provinces. The responses of 12 sugar beet genotypes were evaluated in greenhouse based on the female number on the roots. Moreover, the sizes of females of the nematode populations on each genotype were determined, and egg hatching and emergence of the second stage juveniles (J2s) from the cysts were compared. The cluster analysis of genotypes based on the number and size of the females on the plants showed that the genotypes Toucan, Cactus, Fernando, Sanetta cultivars were clustered with the resistant cultivar Pauletta in one group, and the genotypes035,7112*SB36*SB30, 031, 034 and 7112*SB36*SB28 were clustered with the susceptible control (7112*SB36*SB29) in another group. Fewer and smaller females were produced on the resistant genotypes. Nematode population of West Azerbaijan showed a noticeable difference in pathogenicity with Isfahan population and produced fewer and smaller females. Mashhad population had the highest rate of egg hatching and juvenile emergence from cysts compared to the other populations.