Evaluation of Tobacco Germ Plasm for Resistance to the Tobacco Cyst Nematode,Globodera tabacum solanacearum

Abstract

Twenty-four tobacco genotypes were evaluated in the greenhouse for resistance to a North Carolina isolate of the tobacco cyst nematode Globodera tabacum subsp. solanacearum. The experimental design was a split-plot with eight replications. The experiment was repeated three times. Genotypes were assigned to whole plots, and nematode infestation levels (0 or 10,000 eggs per 1,300 cm 3 of soil) were assigned to subplots. Fresh stalk and root weights of all plants were recorded. Two new variables were created based on these measurements: percent stalk weight [%SW = (SW of infected plant + SW of uninfected plant) x 100] and percent root weight [%RW = (RW of infected plant + RW of uninfected plant) x 100]. Nematode reproduction, measured as number of cysts and eggs per pot, and reproduction factor (final number of eggs + initial number of eggs), was determined for each genotype. Significant differences (P ≤ 0.05) were observed among tobacco genotypes for nematode reproduction. Low levels were detected in the cultivars Burley 21, PD 4, VA 81, NC 567, Speight G-80, Kutsaga Mammoth 10, Kutsaga 110, and in the flue-cured breeding lines Cyst 913 and 9025-1. Differences in vegetative growth among genotypes grown in nematode-infested soil were detected only between those with the highest and lowest %SW and %RW. Genotype shoot and root weight were not correlated with nematode reproduction. Nevertheless, results from these experiments indicate that nematode reproductive parameters may be used to evaluate tobacco germ plasm for resistance to G. t. subsp. solanacearum in the greenhouse.