Resistance of Corn to Southern Root-Knot Nematode
- W. Paul Williams and
- Gary L. Windham
Root-knot nematodes, Meloidogyne spp., are frequently associated with corn, Zea mays L., in the southern USA. Limited information is available on resistance of corn to these nematodes; however, recent investigations indicated that their reproduction varied among green-house-grown inbred lines of corn. This investigation was undertaken to evaluate the performance in crosses of inbred lines showing different levels of resistance to M. incognita and to obtain information on the relative importance of general and specific combining ability. Eight inbred lines exhibiting varying levels of resistance were selected as parents of a diallel cross. Seedlings of the 28 F1 hybrids and the parental inbred lines were evaluated for reaction to inoculation with 3000 M. incognita (Race 4) eggs per plant. After 60 d, the roots were washed and weighed, eggs extracted and counted, and nematode reproduction determined. An analysis indicated that both general and specific combining ability were significant sources of variation in the inheritance of resistance to nematode reproduction. Inbred line Mp307 showed the lowest nematode reproduction (510 eggs/g fresh root) and T216, the highest (4134 eggs/g fresh root). The Mp307 also showed superior general combining ability for resistance whereas hybrids with T216 as one parent were among the most susceptible. Resistance to reproduction of M. incognita is available for developing resistant corn hybrids.
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