Abstract
The degrees of susceptibility of oat cultivars Tachiibuki and Haeibuki to infection by 3 Meloidogyne species (M. incognita, M. arenaria, and M. hapla) were examined. Reproduction rates of 3 M. incognita populations on Tachiibuki in greenhouse experiments were low, and this confirmed our previous field experiments. The reproduction rates of 3 M. arenaria populations were low on Tachiibuki and on Haeibuki, whereas the latter is a suitable host for M. incognita. With regard to invasion of second-stage juveniles (J2), similar rates were observed for M. incognita and M. arenaria on Tachiibuki and Haeibuki roots 5 days after inoculation at 25°C. After 30 days, however, Tachiibuki roots inoculated with M. incognita or M. arenaria contained only a small number of mature females compared to the suitable nematode hosts. Most J2 nematodes on Tachiibuki roots were undeveloped and a relatively high percentage of males was observed. We conclude that the low rates of reproduction of these 2 root-knot nematode species on Tachiibuki can be attributed to the inhibition of development from the J2 stage to mature females. For the 3 M. hapla populations, reproduction was close to zero and root invasion was minimal on both oat cultivars.
