Diallel Analysis of Fiber Quality Traits with an Emphasis on Elongation in Upland Cotton

Abstract

The upland cotton (Gossypium hirsutum L.) industry in the United States has shifted from a domestic market to an export‐based market that mandates simultaneous improvements of yield and various fiber traits to maintain competitiveness. Fiber elongation (ability to stretch before breaking) is one of the key fiber parameters in determining yarn quality. It is a trait that is largely understudied due to an absence of monetary incentives for growers to produce high‐elongation cotton fibers. Five upland genotypes were selected as representatives of major upland cotton germplasm pools in the United States. These genotypes and their 10 F1 progenies were grown in College Station, TX, in 2010 and 2011, and fiber properties were tested in a diallel analysis. Overall, general combining ability was greater than specific combining ability for fiber elongation, suggesting the predominance of additive gene action. Two parental lines, cultivar PSC 355 and germplasm line Dever Line 8, were identified as good combiners for fiber elongation when fibers were measured with the High Volume Instrument (HVI) and the Stelometer. A highly significant negative correlation was observed between fiber upper‐half mean length and elongation, whereas a slight negative correlation was observed for elongation and strength. Stelometer and HVI readings for elongation were correlated with r value of 0.69.

Divergent Selection for Fiber Length and Bundle Strength and Correlated Responses in Cotton

“…Within populations, this correlation did not hold for F 2:5 strains derived from ESU624 ´ ELSU33 and TAM22 ´ SID84. Ng et al (2014) reported similar observations regarding the negative correlation between UHML and Elon in experimental populations grown at College Station. Fiber micronaire responded negatively to selection for UHML across all populations.…”

“…Considering that realized heritability provides an estimate of how much of the selection differential imposed was observed as a response in the progeny, these results suggest that early generation selection for UHML and Str is highly effective at College Station, with the exception of progeny derived from ESU624 ´ ELSU33. The results further suggest that the negative correlation between UHML and Elon is more than an artifact attributable to the positive correlation between UHML and Str, and combined with the results reported by Ng et al (2014), suggest that further investigation into the negative relationship between UHML and Elon is warranted. Several F 2:5 strains with improved UHML and/or Str and no associated reduction in LP were identified within each population, providing further evidence that the negative relationship between fiber quality and lint yield is, at least in part, attributable to repulsion phase linkage.…”

“…The results reported herein suggest that variation for fiber quality exists within the Texas A&M AgriLife Research upland cotton germplasm to improve UHML and Str without a concomitant reduction in LP. The results further suggest that the negative correlation between UHML and Elon is more than an artifact attributable to the positive correlation between UHML and Str, and combined with the results reported by Ng et al (2014), suggest that further investigation into the negative relationship between UHML and Elon is warranted. Table 6.…”

Generation Means Analysis for Fiber Elongation in Upland Cotton

“…From that preliminary study and results from previous diallel analysis, four parents, DEV, MD9, TAM, and ARK, were chosen for the GMA study (Ng et al, 2013). From that preliminary study and results from previous diallel analysis, four parents, DEV, MD9, TAM, and ARK, were chosen for the GMA study (Ng et al, 2013).…”

“…Three of the four parents, that is, ARK, MD9, and DEV, were previously studied in a diallel analysis for fiber elongation by Ng et al (2013), and the results from that study suggested further dissection into gene actions governing fiber elongation. The small sample sizes of these parental plants prohibited the use of HVI to measure elongation, and the Stelometer was chosen as an alternative, as previous study has shown good correlations between the two systems (Ng et al, 2013). Six distinctive families were created, with each family consisting of six generations: P 1 , P 2 , F 1 , F 2 , BCP 1 , and BCP 2 .…”