Resistance of sugar beet to the cyst‐nematode Heterodera schachtii Schm.

Abstract

SUMMARYLines exhibiting heritable resistance and susceptibility to beet cyst nematode were selected from a heterogeneous cultivated variety of beet but no major gene resistance was detected although many hundreds of lines of wild and cultivated varieties were tested. Recurrent selection improved the resistance of one line, selected originally for yield and non‐bolting qualities, when progenies in each generation were compared with susceptible controls and with the original ancestral lines. Resistance was inherited by progenies from selections crossed with susceptible plants, but evidence of some reduction in resistance was detectable where fewer eelworms were available to invade from the soil. There was no evidence of heritable cytoplasmic influence on the resistance. Resistance is probably controlled by a polygene system in sugar beet, although immunity in Beta procumbens and B. webbiana and near‐immunity in B. patellaris suggest that in other species of Beta major gene resistance may occur.