Effect of Verticillium Wilt on Fiber Quality Among Different Cotton Varieties

Verticillium wilt, caused by the soilborne fungus Verticillium dahliae Kleb., is an economically important disease of cotton in the High Plains of Texas. While the effect of the disease on yield is well documented, the influence of Verticillium wilt on fiber quality is poorly understood. The objective of this research was to examine the effect of V. dahliae on fiber properties of different cotton varieties under two seeding rates. A field experiment was conducted in Donley County, Texas during the 2014 growing season. Treatments were arranged in a split plot design with three replications. Whole plots consisted of the susceptible variety Deltapine 0912B2RF and partially resistant varieties All-Tex Nitro-44B2RF, Fibermax 2484B2F, NexGen 4111B2RF, with seeding rates (70,000 and 35,000 seeds per acre) serving as sub-plots. Plant stand and disease incidence were measured throughout the growing season. Lint yields were estimated for each plot and samples were conventionally ginned to determine lint turn out. Subsamples of lint were subjected to the Texas Tech University Fiber and Biopolymer Research Institute for high volume instrument (HVI) and advanced fiber information system (AFIS). Plant stands were significantly different among varieties. Stands were highest for Fibermax 2484B2F (2.3 plants/foot) and lowest for NexGen 4111B2RF (1.9 plants/foot). Fibermax 2484B2F was superior in disease resistance (26.5%) to Deltapine 0912B2RF (47.3%). Disease incidence was greater for the lower seeding rate (45.2%) compared to the higher seeding rate (30.3%). Yields in these studies were negatively affected by the disease (P=0.0010). Yield increases over Deltapine 0912B2RF were 325, 316, 275 lb/A for All-Tex Nitro-44B2RF, Fibermax 2484B2F and NexGen 4111B2RF, respectively. Disease incidence was negatively correlated with staple length (P=0.0009), length by weight (P=0.0411), upper quartile length by weight (P=0.0087), 5%-length by number (P=0.0030), and reflectance (P=0.0289), whereas, nep size (P=0.0124) and seed coat nep count (P=0.0281) increased under Verticillium stress.