Response to nematicide by cotton genotypes varying in reniform nematode resistance

Reniform 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 (Ren(barb1) and Ren(barb2)) 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 Ren(barb1), 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.

Automated summary

The study compared the performance of breeding lines with QTLs for RN resistance in RN-infected and non-RN fields, revealing the significant role of resistant QTLs in reducing RN egg numbers and increasing yields. While adding a nematicide treatment increased yields in all materials tested, further research on increasing resistance from other genetic sources is still needed to completely eliminate the use of nematicides.