Performance Evaluation of Lonren-1 Genotypes In Response to Nematicides

Abstract The reniform nematode (Rotylenchulus reniformis) is one of the most damaging pests to cotton crops grown in the Southeastern region of the United States. Germplasm lines LONREN-1 and LONREN-2 have recently been released for cotton breeders to use in introgression with desirable cultivars to establish resistance. Previous screenings for reniform resistance in development lines have demonstrated that some lines are indeed highly resistant. However, when high numbers of reniform nematodes are present, severe stunting in the seedling stage is very common within these resistant development lines. The overall hypothesis of this study is that applying nematicides as seed treatments will reduce nematode pressure in the seedling stage and allow resistant lines to reach a point where they can withstand the damage caused by the nematodes. The LONREN-1 genotype, three resistant lines from the LONREN-1xFM966 cross, one susceptible line from the LONREN-1xFM966 cross, and the susceptible cultivar DP393 were treated with nematicides and their performances evaluated in a field trial and micro-plot experiment. Plant heights and vigor ratings were recorded at approximately 30, 45, 60, and 90 days after planting (DAP). Reniform populations were recorded at 30, 60, 90, and 160 DAP. Overall means of yield data will be analyzed after the harvest of test plots. In both field trial and micro-plot experiments, an increase in plant heights and vigor ratings could be found at 30 and 45 DAP in both resistant and susceptible entries that had been treated with nematicides. However, when comparing the resistant lines to the susceptible lines, the susceptible lines displayed higher plant heights and vigor ratings. In all the resistant line entries a reduction in reniform populations was observed at 30 DAP in the field trial experiment.