Influence of Cytokinin on In Vitro Screening of Peaches for Resistance to Nematodes. R. N. Huettel, Microbiologist, ARS, U.S. Department of Agriculture, Beltsville Agricultural Research Center, Beltsville, MD 20705. F. A. Hammerschlag, Research Plant Physiologist, ARS, U.S. Department of Agriculture, Beltsville Agricultural Research Center, Beltsville, MD 20705. Plant Dis. 70:1141-1144. Accepted for publication 15 April 1986. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1986. DOI: 10.1094/PD-70-1141.

Growth on two levels of the cytokinin 6-benzylamino purine (BA) influenced the initial in vitro response of peach rootstock Nemaguard plantlets to Meloidogyne incognita but did not influence the response of the scion cultivar Jerseyqueen. The high level (2 mg/ L) of BA resulted in an initial loss of resistance to M. incognita as evident with initial galling; however, the nematodes failed to develop to maturity and the plantlets recovered. This initial susceptible response was not observed in vitro after growth on the lower level (0.2 mg/ L) of BA. Plantlets derived from Nemaguard and Jerseyqueen propagated and rooted in vitro were susceptible to Pratylenchus penetrans and differed significantly from controls in root weight, stem height, and numbers of leaves. This research suggests that in vitro screening of self-rooted peach lines may facilitate early detection of resistance to M. incognita regardless of the cytokinin influence.