Effect of different production practices on the development of verticillium wilt and cotton fiber quality

Verticillium wilt, caused by the soilborne fungus Verticillium dahliae Kleb., is an economically damaging disease capable of reducing yield and fiber quality of cotton (Gossypium hirsutum L.). To date, aspects of integrated disease management of Verticillium wilt on cotton yield and fiber quality are not entirely understood. In addition, limited information is available regarding the effects of common production practices on the epidemiology of Verticillium wilt. Furthermore, the effect of Verticillium wilt on boll distribution and fiber quality of different fruiting sites is lacking. Therefore, the objectives of this study were to 1) evaluate the effectiveness of different planting dates, seeding rates, and cultivars on suppressing Verticillium wilt; 2) simulate the temporal dynamics of Verticillium wilt in cotton for different seeding rates and cultivars; 3) examine the relationship between wilt incidence, lint yield, and various fiber quality properties under different management strategies; and 4) explore the effect of Verticillium wilt on boll distribution and fiber quality of different cultivars through box mapping. To achieve these research objectives, field experiments were conducted from 2013 to 2016 in various locations on the Texas High Plains naturally infested with V. dahliae. Results indicated that later planted cotton led to a reduction in disease incidence; however, lint yields and net returns compared to the early-planted cotton were also reduced. Later planted cotton had lower micronaire and fiber length compared to the earlier planting of cotton. Wilt incidence decreased when planting partially resistant cultivars at higher seeding rates at all locations. Lint yields were negatively affected by Verticillium wilt in most trials across growing seasons. Net returns were reduced about 19% for susceptible cultivar under high levels of disease compared to the partially resistant cultivar. When characterizing temporal progress, Gompertz, logistic, and exponential models were better fit than the linear model. Among these nonlinear growth models, the Gompertz model was determined to be the best fitting model for simulating the Verticillium wilt epidemics. Disease incidence correlated with many basic and advanced fiber properties. In 2014, fiber length, reflectance, upper quartile length by weight, and 5%-length by number were negatively affected by the disease, whereas, nep size and seed coat nep amount increased with increasing disease levels. In 2016, fiber length, reflectance, and uniformity were negatively correlated with wilt incidence. In addition, the fiber length by number, 5%-length by number, and upper quartile length by weight were negatively correlated with wilt incidence; however, an overall positive relationship between short fiber content and length variation and wilt incidence was demonstrated. Results also indicated that the earliness increased with the aggravated wilt levels (<5% to ~100% defoliation). A decreasing trend for most fiber properties measured by HVI was associated with the increase of cohort numbers. The main yield contributing cohorts of 2 to 9 had longer fiber than the vegetative and upper canopy cohorts (10 and 11). The increase of nep size and count and decrease of total trash and visible foreign matter measured by AFIS were also identified with the increase of cohorts. While Verticillium wilt is capable of greatly affecting yield, these results indicate that greater losses will be attributed to reductions in basic fiber quality properties, as well as fiber properties that will limit use of lint in high throughput, ring spinning manufacturing systems.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Plant and Soil Science

Grantor

Texas Tech University

Year dc:date.issued

2017

Author dc:creator

• Liu, Xiaoxiao

Chair dc:contributor.committeechair

• Woodward, Jason

Committee members dc:contributor.committeemember

• Kelly, Brendan
• Lewis, Katie
• Byrd, Seth
• Morgan, Gaylon

• Verticillium dahliae Kleb
• Lint Yield
• Fiber Quality
• Seeding Rate
• Partially Resistant Cultivar
• Modeling Disease Dynamics

Language dc:language.iso

eng

Handle dc:identifier.uri

https://hdl.handle.net/2346/88945

OAI identifier oai:identifier

oai:ttu-ir.tdl.org:2346/88945