Project Summaries

11-898  Project Manager: D. C. Jones

TARGETING CONSISTENTLY MATURING HIGH-QUALITY COTTON VARIETIES FOR TEXAS

Mourad Krifa, University of Texas at Austin

Despite tremendous progress made in increasing fiber length of Texas cotton from breeding improvements, variability of maturity within and between seasons threatens to compromise these gains. Low maturity levels often equate with high propensity to damage which compromises fiber length and length distribution. This research aims at identifying solutions to overcome the impact of the intra- and inter-season variability in maturity on the use-value and marketability of near-long staple cotton varieties developed for the Texas Plains. It seeks to develop a multiparametric measure of the contrast between fiber traits across low and full maturity, and evaluate its variability among genotypes currently being bred to serve the Texas Plains growers. Based on the results obtained in this preliminary phase, it appears there is variability in micronaire within different genotypes. If confirmed, these results could help identify genotypes with robust fiber quality traits that minimize micronaire variability. Achieving this objective will enable geneticists, agronomists and growers to identify solutions in order to overcome the problem of inconsistent quality of Texas High Plains cotton.

The ultimate objective of this research is to identify solutions to the problem of inconsistent maturity and its impact on the use-value and marketability of near-long staple cotton varieties developed for Texas. In this initial phase, the specific objective is to evaluate the potential for between-genotype variability in the response to micronaire variation in order to develop an approach to using the contrast in fiber traits between low maturity and full maturity phases for genotype selection.  Lint from the same genotypes, but from differing maturity phases, was obtained in two ways: 1) Samples showing the desired maturity levels were selected from genotypes grown in different environments (locations/seasons), and 2) Samples were selected from soil-water deficit trials conducted at the Drought Tolerance Laboratory at the Texas AgriLife Research and Extension Center in Corpus Christi. The available population consists of varieties with similar length potential but with anticipated differential response in micronaire when exposed to favorable and unfavorable growing conditions.  Lint harvested in both tests was evaluated for individual fiber properties on commercially available instruments (Advanced Fiber Information System) to evaluate length, fineness, and maturity parameters.

The first task achieved in 2012 was to explore the potential for between-genotype variability in the response to micronaire variation. The primary question we tried to answer was whether different genotypes would present differential responses to variations in maturity, i.e., different contrasts in fiber traits between low maturity and full maturity phases. This was achieved using two approaches: 1) Lint samples were obtained from individual plants exhibiting a gradient in maturity within genotype. The plants were grown under strictly controlled conditions in the drought tolerance lab in Corpus Christi. Analysis of the properties of individual fibers using AFIS allowed correlating the variation in fiber traits to the variation of maturity within genotypes. We examined the data for the relationship between maturity and other fiber properties within genotypes and observed different patterns among genotypes. An example of a differential response to variation in maturity for short fiber content; a similar pattern was observed for other length distribution dispersion parameters and for fiber entanglements. 2) The second set of lint samples tested was obtained from large plot trials conducted in Lubbock and College Station, TX between 2007 and 2009. In this case, the range of maturity was obtained because of the various environments (3 environments x 3 plots). Here too we examined the data for the relationship between maturity and other fiber properties obtained on the individual plots within genotypes and observed different patterns among genotypes. Samples were selected from the genotypes discussed above (both individual plants and stripper-harvested plots) and were tested for intrinsic fineness (fiber perimeter) and cell wall thickness (maturity) using cross-section analysis. The direct measurement of both fineness and maturity will allow the identification of the differences between the groups outlined within the scatter plots above, and may offer explanatory elements that will help explain the different patterns.

Based on the two exploratory studies described above, the observed potential for between genotype variability in the response to maturity variation appears consistent with the hypotheses put forth when this project was proposed. The differential response we observe could indicate a difference in the sensitivity-to-maturity of the corresponding genotypes. However, the results obtained this year remain preliminary.

 

Project Year: 2012
 

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