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The Assessment and Selection of Fiber Related Traits to Improve Fiber Strength and Length
Abstract
The first project, “Propensity to Break” in Chapter 1, examined a fiber’s ability to endure mechanical stress which often leads to the accumulation of short fibers. Reducing fiber breakage will reduce short fiber content (SFC) and enhance the relative value of cotton. Fiber length distributions of 56 diverse cotton lines, including modern and obsolete cultivars, were determined using the Advanced Fiber Information System (AFIS) before and after subjecting them to a MDTA3 cleaning process to replicate tensile strain. Due to environmental weathering of cotton fibers in the field prior to harvest, results were mixed year-to-year, but observable differences were found among genotypes and new individuals were classified as high- or low-propensity to break, indicating a greater or reduced accumulation of short fiber, respectively. Additionally, we propose a new equation for assigning statistical significance to the accumulation of short fibers which may serve to better identify high- or low-propensity to break individuals and suggest the utilization of this technique to explore potential resistance to fiber weathering.
The second project, “Within-Boll Yield Component Analysis” (Chapter 2) examined relationships between fiber quality measurements produced via AFIS and High Volume Instrumentation (HVI) and elucidates the synergistic/antagonist interactions of within-boll measurements for a diverse panel of more than 200 sib lines in a multi-year study. Many of these sib lines were developed by the Cotton Improvement Lab, having exceptional length and strength potentials. Key concerns were: 1) lint percentages are often unintentionally reduced in the pursuit of greater length and strength potentials, 2) simultaneous improvement of both yield and fiber quality is, at best, challenging, and 3) improvements of fiber length and strength often comes at the expense of other fiber traits. Our findings reinforce the hypothesis that the pursuit of improved lint percentages leads to smaller seeds, less seeds per boll, and shorter fiber lengths. Additionally, data suggests that antagonistic relationships between fiber bundle strength (FBS) and within-boll traits do not readily exist in this population of unique individuals. While simultaneously improvement of both yield and fiber quality is challenging, we observe extensive diversity within the experimental population for many fiber traits which may lend itself to eroding more of these antagonistic relationships that often impede breeding efforts.
In Chapter 3, HVI FBS and its inheritance are explored in detail in testcross generations that combine novel germplasm of TAMU extra-long staple upland (ELSU) cotton genotypes with a commercial cultivar (ALL-TEX 7A21) with high lint percentage but standard fiber length and strength qualities. The development of extra-long staple varieties has been plagued by low lint percentages, limiting their adoption in a commercial setting. Twelve ELSU lines were crossed with ALL-TEX 7A21 to produce F1 progeny which were self-pollinated to the F2 generation and used to create reciprocal backcrosses. Gene effects, genetic variances, and both broad- and narrow-sense heritability were calculated for FBS. The results indicated a propensity for genetic effects to be predominantly additive but also suggested the role of epistatic interactions that were often duplicate and dominant in nature, and thus, complicate making selections for FBS in early generations. Despite immense environmental variation, models of heritability for FBS were relatively high but heterosis for FBS was limited in the progeny suggesting other parental material may be better suited to cross with these ELSU lines.
Citation
Gendron, Jake Michael (2023). The Assessment and Selection of Fiber Related Traits to Improve Fiber Strength and Length. Doctoral dissertation, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /199063.