Response to nematicide by cotton genotypes varying in reniform nematode resistance

Abstract

AbstractReniform nematode (RN, Rotylenchulus reniformis Linford & Oliveria) is a parasite that reduces and limits cotton (Gossypium hirsutum L.) yields. At present, nematicides and crop rotations are the most effective management tool for producers. Our study investigated the use of six composite breeding lines that have quantitative trait loci (QTLs) for RN resistance and the interaction effect of a nematicide under high RN pressure. The study compared these genotypes in both a non‐RN field and a RN‐infected field under a Velum Total (active ingredients fluopyram and imidacloprid) treatment at Tennessee Valley Research and Extension Center near Belle Mina, AL. In both years, the breeding lines outyielded commercial controls and the parental lines in RN infested field with and without Velum Total. Five out of the six breeding lines contained both chromosome 21 (Renbarb1 and Renbarb2) resistant QTLs, which reduced RN egg numbers (P < .05) and produced higher yields than the commercial checks. These lines can be considered moderately resistant to RN. The remaining line contained one QTL Renbarb1, produced good yield, and is considered tolerant, despite the fact that it had high RN egg numbers. However, adding a nematicide treatment did increase yields in all material tested. Therefore, further work at increasing resistance from other genetic sources is needed to completely eliminate nematicide use.