Growth, Development and Yield Characteristics of Rotylenchulus Reniformis Resistant Cotton Lines Grown in Nematode-Infested Fields.

Reniform nematode has been identified as one of the major biotic factors limiting yield, exceeding 8% on average, in the Mississippi Delta. With no commercially available cultivars resistant to this pest, producers have been limited to chemical control methods. Recently, experimental crossing with Gossypium barbadense resulted in advanced G. hirsutum breeding lines exhibiting resistance to reniform nematode infection. An experiment was conducted to evaluate these new resistant cotton lines (08SS110-NE06 and 08SS100) along with commercial susceptible cultivars (Deltapine 16 and PHY 490 W3FE) to reniform nematode infection based on plant growth, development, and yield responses. All four genotypes were grown in the soils naturally infested with reniform nematode exceeding or at economic thresholds for Mississippi. Classical growth analysis was conducted for a two-meter row length at every 1-2 week interval following emergence and was used to derive crop growth responses. Significant genotypic variability was observed for: (1) classical growth traits such as plant height, leaf area, and dry biomass, (2) derived crop growth indices such as crop growth rate and leaf area index, (3) physiological traits such as net photosynthesis, and (4) lint yields. Resistant line 08SS110-NE06 and susceptible cultivar PHY 490 W3FE showed significantly the highest and the lowest values for most of the measured and calculated traits throughout the growing season. Further, resistant lines had greater lint yields than susceptible cultivars. A significant decline in reniform nematode populations was observed at the end of the season in plots cultivated with resistant lines when compared with preplant populations. The results indicate that inherit resistance mechanism against reniform nematode in the resistant lines 08SS110-NE06 and 08SS100 reduces infestation and reproduction potential of reniform nematode, and thus alleviating nematode pressure on growth and development.