Characterizing Resistance to Reniform Nematode in Accessions of Gossypium barbadense Based on Classical Growth Analysis.

Development of resistant cotton cultivars is in progress to reduce cotton losses attributed to reniform nematode, which causes up to 8% reduction in cotton production every year in the US. A two-year field experiment was conducted to evaluate responses of two newly developed reniform nematode resistant cotton lines (accessions of Gossypium barbadense; 08SS110-NE06.OP and 08SS100) along with two commercial cotton cultivars (Deltapine 16 and PHY 490 W3FE) to reniform nematode infection using classical growth and development. All four genotypes were grown in field-plots that had reniform nematode population exceeding economic thresholds for Mississippi. Various growth and development traits of all four genotypes were measured through destructive harvesting of two meter row lengths at every two-week intervals following fourth leaf-stage. In addition, soil samples were taken from top 15 cm soil depth in the plots during planting and harvesting for reniform nematode population counts. The results showed that reniform nematode resistant cotton line had significantly greater plant height, dry weights, and leaf area index than commercial cotton cultivars. The resistant line 08SS110-NE06.OP showed higher lint yields than commercial cultivars in both the years. While reniform nematode population significantly reduced at the end of the season in the plots where resistant lines were grown, compared to commercial cultivars. Greater vigor and lower nematode infestation might have contributed to increased yields in the resistant lines than commercial cultivars. The study provided useful information to breeding programs about the agronomic characteristics of the novel resistant cotton lines under reniform nematode infested field conditions.