Evaluation of the activity of dhurrin and sorghum towards Meloidogyne incognita

The epidermal cells of leaf and roots of sorghum (Sorghum bicolor), sudangrass (S. sudanensis) and sorghum-sudangrass hybrids (S. bicolor x S. sudanensis) contain the cyanogenic glucoside dhurrin, which can degrade into hydrogen cyanide (HCN), well known for its toxicity to many organisms, including nematodes. In vitro bioassays were carried out with the aim of evaluating the nematicidal and the nematistatic effects of dhurrin concentrations on second-stage juveniles (J2) of Meloidogyne incognita, and the effectiveness of dhurrin in decreasing or preventing hatching of M. incognita. Furthermore, Sorghum hybrid cv. Super Dolce 10, selected for its dhurrin content, and Eruca sativa sel. Nemat were used in two glasshouse experiments to study the host-nematode relationship and the development of M. incognita life cycle in the roots. In the in vitro bioassays, Sorghum hybrid cv. Super Dolce 10 showed an inhibitory effect on hatching, a slow nematicidal effect on J2 and no nematistatic activity. In the glasshouse experiments, both Sorghum hybrid cv. Super Dolce 10 and E. sativa sel. Nemat proved to be a poor to non-host of M. incognita, with reproduction factor (R) always <1, compared with Solanum lycopersicum cv. UC82, an excellent host (R = 43). In both bioactive accessions two generations were completed in 15 weeks (four cycles in S. lycopersicum), but with the production of very few egg masses, while root infestation was also always very low, with gall index (G.I.) < 1, compared with S. lycopersicum (G.I. = 4). In this study, the effectiveness of E. sativa sel. Nemat in controlling M. incognita confirmed data from previous work.