Yield of Peanut Genotypes Resistant to Root-Knot Nematodes1

Yields of six runner-, two spanish-, and one virginia-type breeding lines of peanut with resistance to the root-knot nematode, Meloidogyne arenaria, were compared to yields of susceptible cultivars in nematode-infested and noninfested field plots in 1996. Pod yields of resistant runner-, virginia-, and one of the spanish-type breeding lines were 1.5 to 4 times greater (P = 0.05) than pod yields of the susceptible cultivars Florunner, NC-7, and Tamspan 90 in two nematode-infested fields. Final nematode population densities on most resistant breeding lines were lower (P = 0.05) than those on the susceptible cultivars. In the noninfested field, all but one runner- and the two spanish-type resistant breeding lines had pod yields that were not different from that of the susceptible cultivars. Yields of the resistant breeding lines ranged from 3890 to 5152 kg/ha in the noninfested field. In 1997, yields of three of the runner-type breeding lines were compared to the yields of Florunner and Tamrun 96 in three fields not infested with M. arenaria. In one field, no differences were observed in pod yield among the breeding lines and cultivars; in the second field the yield of two of the breeding lines were not different from the susceptible cultivars; and in the third field, only TP259-3-5 had pod yield equivalent to that of the susceptible cultivars. These data indicate that resistant runner-type genotypes with high yield potential have been developed, but additional breeding efforts are needed to develop nematode resistance in high yielding spanish- and virginia-type peanuts.