REACTION OF SUNFLOWER GENOTYPES TO PRATYLENCHUS BRACHYURUS AND MELOIDOGYNE JAVANICA

Sunflower is commonly grown as a rotation crop with soybean. However, it may be susceptible to some plant-parasitic nematode species. This study aimed to assess the reaction of sunflower genotypes to Pratylenchus brachyurus and Meloidogyne javanica. Twelve sunflower genotypes (BRS 323, BRS G73, BRS G74, BRS G75, BRS G76, BRS G77, BRS G78, BRS G79, BRS G80, BRS G81, Altis 99, and Helio 250) were evaluated using soybean as a susceptibility reference. Greenhouse experiments were conducted for each nematode species in a completely randomized design with eight replicates; the experiments were conducted twice. Plants were inoculated with 500 P. brachyurus or 2,000 M. javanica and evaluated at 75 and 60 days after inoculation, respectively. The number of nematodes per gram of root and reproduction factor (RF=final population/initial population) values were determined. Sunflower genotypes were moderately resistant or resistant to P. brachyurus, with RF values ranging from 0.3 to 1.8 in Trial 1 and from 1.0 to 2.5 in Trial 2. For soybean, RF values were 7.0 and 25.3 in Trials 1 and 2, respectively. By contrast, sunflower genotypes were susceptible to M. javanica, with RF values ranging from 40.8 to 178.2 in Trial 1 and from 5.0 to 20.6 in Trial 2. These values were similar or higher to those recorded for soybean (114.0 and 3.3 in Trials 1 and 2, respectively). The findings indicate that sunflower can be grown in areas infested with P. brachyurus but is not recommended for areas infested with M. javanica.