Postinfection development of Rotylenchulus reniformis on resistant Glycine max genotypes.

Soybean (Glycine max) lines JTN-5203, PI 404166, and 02011-126 support less root infection by reniform nematode (Rotylenchulus reniformis), but post-infection effects of these lines on the parasite have not been investigated. In this study, post-infection development and fecundity in these lines were compared with that of the susceptible control cultivar Braxton. The infection cycle was divided into early (up to 10 days after inoculation (DAI)) and late (15-30 DAI) phases, during which root-associated nematodes were classified as vermiform, swelling, reniform, or gravid. Repeated experiments were conducted in a growth chamber in containers filled with steam pasteurized soil mix. Seedlings were inoculated with 500 nematodes (mixed vermiform life stages). Containers were arranged in a completely randomized design. As early as 10 DAI, slightly delayed development was observed on resistant lines with half as many gravid nematodes as Braxton. Line 02011-126 had a higher proportion of swelling nematodes than the other resistant lines in late phases, suggesting different resistance mechanisms. All resistant lines inhibited fecundity, with an up to 98% reduction at 30 DAI. In summary, fewer infections, slower development, and reduced reproduction all contribute to resistance in these lines.