Crop Science and Agriculture

The abundance and identity of plant-parasitic and terrestrial non-parasitic nematodes in rhizosphere soil and root samples of commercial Glyphosate-Tolerant (GM) and conventional (CS; non-glyphosate tolerant), soybean cultivars from cultivated fields were obtained for two consecutive growing seasons in South Africa. In addition, the same were done for adjacent natural veld areas. 13 plant-parasitic nematode genera and 31 species associated with both GM and conventional soybean cultivars and with natural veld areas were established. In general, root-knot (Meloidogyne spp.) and root-lesion (Pratylenchusspp.) nematodes dominated in the roots of both types of soybean cultivars. In rhizosphere soil, either Helicotylenchus or Scutellonema were the predominant genera. Conventional soybean cultivars hosted the highest nematode diversity (11 genera and 22 species), followed by natural veld (nine genera and 22 species) with those in GM cultivars being the least diverse (10 genera and 17 species). Six species, viz. Pratylenchus fl akkensis, Pratylenchus scribneri, Pratylenchus vulnus, Rotylenchus brevicaudatus, Telotylenchus avaricus and Quinisulcius capitatus, are fi rst reports for soybean in South Africa. 32 non-parasitic nematode genera occurred in rhizosphere soils of the two soybean ecosystems 23 in CS and 21 in GM soybean) with 28 genera occurring in natural veld areas. Bacterivorous were most diverse in soils of the two soybean ecosystems during both seasons, while fungivores tended to be more abundant in GM soybean fi elds especially during the second season. Novel information has been generated with this study, representing the fi rst for GM soybean crops in South Africa.