evaluation of different sugar beet populations for resistance to beet cyst nematode (heterodera schachtii schmidt(

in this research, 30 sugar beet breeding populations developed by crossing of sugar beet monogerm and multigerm male strile lines with nematode resistant wild sources (w-1009 contaning resistance gene from beta procumbens and w-1010 contaning resistance genes from beta maritima) were compared with resistant and susceptible checks with respect to nematode resistance and yield. the experiments were conducted as randomized complete block design with four replications in 2005- 2006, under beet cyst nematode (bcn) infested fields in mashhad and khoy areas. the reproductive factor (rf) of bcn was also estimated. the number of eggs and larvae of the nematode in the first and second year of the trials in the two areas was 424 and 476 cysts or larvae per 100g soil, respectively. the results of field trials and cluster analysis based upon sugar yield showed that the genotypes 231×(msc2×w-1009)-p, 231×(msr×w-1009) ×fc709-2, 231×(msr×w-1010) and 231×(ms261×w-1010) had high yield potential and were grouped with the foreign resistant check in the same cluster. however, the genotypes 231×(msr×w-1010), 231×(20447×w-1009), 261×(ms20314×w-1009) and 231×(mc2×w-1009) had the lowest reproduction factor (rf) in the field trials. therefore, the above-mentioned genotypes could be used for developing nematode resistant varieties. among those, the genotype 231×(msr×w-1010)  was superior to the resistant checks with respect to both traits and thus it was identified as a resistant genotype with a high yield potential.