Relationship between Rps 1k gene and resistance to Pythium ultimum and P. irregulare in soybean

ABSTRACT In soybean Pythium spp. produces seed and root rot and “damping off”. The aim of this study was to verify the relationship between resistant gene Rps 1k to Phytophthora sojae with Pythium ultimum and P. irregulare. Four genotypes of soybean were sown on inoculated soil, two of them with gene Rps 1k and the other two without it. Genotypes without the gene did not differ among themselves, no matter whether they were inoculated or not. On the other hand, Rps1k genotypes differed from each other, whether or not they were inoculated. SE+2 presented 95% of emergence whereas SE+1 presented 78.35% of emergence, but in both cases the emergence decreased when genotypes were inoculated with 63.35% and 34.15% respectively. Under the assayed conditions the gene Rps1k resistant to Ph. sojae did not show a greater number of emerged seedlings against the tested strains of P. ultimum or P. irregulare.