Submitted to: American Peanut Research and Education Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: April 15, 2005
Publication Date: December 15, 2005
Citation: Dong, W., Holbrook Jr, C.C., Timper, P., Brenneman, T., Noe, J.P. 2005. Development and utilization of a more rapid assessment method to identify resistance to Meloidogyne arenaria in peanut [abstract]. In: Proceedings of the American Peanut Research and Education Society, July 11-15, 2005, Portsmouth, Virginia. 37:35. Interpretive Summary: not required
Technical Abstract: During 2002-2004, pot trails were conducted in Tifton, Georgia to develop and evaluate a more rapid method for assessing resistance to M. arenaria (Ma) in peanut under greenhouse conditions. Four peanut genotypes with different levels of resistance to Ma were inoculated with either eggs or second-stage juvenile (J2) at two different concentrations (2000 J2, 4000 J2, 8000 eggs, and 16000 eggs per pot). Plants were rated for resistance using gall indices and gall counts at 2 and 4 weeks after inoculation (WAI). These ratings were than compared to resistance ratings (gall index, gall counts, and eggs/g root) made at 6 and 10 WAI. Logistical considerations favor the use of the 8000-egg inoculum method. Gall number or an index based on percentage of roots that are galled can be used to separate the different levels of resistance in peanut two weeks (150 degree days) after inoculation. Consistent reductions in nematode reproduction can be identified 6 WAI (about 520 degree days) and 10 WAI, based on egg mass index or eggs/g root. The results of the rapid screening method (2 WAI) were similar to the conventional method (7 WAI) when 40 peanut plants were assessed for resistance to Ma. Pearson’s correlation coefficients were calculated to compare the galling indices and gall number. Significantly positive correlations (P<0.01) were observed among galling index systems and gall number. We propose a two-stage greenhouse screening protocol to identify peanut genotypes with resistance to the root-knot nematode. A preliminary screen would first be used to eliminate susceptible genotypes based on gall number or percent root galled 14 days (150 degree days) after inoculation with 8000 eggs. The selected genotypes should then be assessed for egg mass index or egg number per gram fresh root at 6 weeks (520 degree days) after inoculation to verify the resistance.