Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/23/2016
Publication Date: 10/12/2016
Citation: Hugie, K.L., Smith, W., Joy, K.S., Jones, D.C. 2016. Divergent selection for fiber length and bundle strength and correlated responses in cotton. Crop Science. 57:99-107.

Interpretive Summary: Cotton breeders must develop cultivars to meet the demand for longer, stronger, and more uniform fibers. One challenge regarding the improvement of cotton fiber quality is identifying parental combinations with sufficient genetic variation. The negative relationship between fiber quality and lint yield must also be considered as a limitation to the improvement of fiber quality. The objectives of the current study were to measure the effectiveness of selection for fiber length and strength in five genetically diverse populations and to measure the correlated responses to selection for fiber length and strength. Our results indicate that there is ample genetic variation among the five populations and that early generation selection for fiber length and strength is an effective strategy for the improvement of fiber quality. Our findings also suggest that further investigation into the negative relationship between fiber length and elongation is warranted.

Technical Abstract: Cotton breeders must develop cultivars to meet the demand for longer, stronger, and more uniform fibers. In the current study, two cycles of divergent selection for fiber upper-half mean length (UHML) and bundle strength (Str) were conducted within five diverse parental combinations selected based on their potential for the genetic improvement of fiber quality. Realized heritability estimates for UHML and Str were calculated for each cycle, and correlated responses among fiber properties and lint percent (LP) were measured as they responded to selection for UHML and Str. The results suggest that early generation selection for UHML and Str is an effective strategy for the genetic improvement of fiber quality at College Station, Texas. Although UHML and Str were consistently negatively correlated with LP, the results demonstrate that sufficient 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. A negative phenotypic correlation between UHML and fiber elongation (Elon) was also observed and was independent of the association between Str and Elon in multiple populations. These findings suggest that further investigation into the relationship between UHML and Elon within the Texas A&M AgriLife Research germplasm is warranted.