Registration of 13AFX6 and 13AFX13 cotton germplasm lines with improved fiber strength and length

Abstract

13AFX6 (Reg. no. GP-1151, PI 705849) and 13AFX13 (Reg. no. GP-1150, PI 705848) are noncommercial breeding lines of cotton (Gossypium hirsutum L.) released by the USDA-Agricultural Research Service in 2023. 13AFX6 and 13AFX13 display superb fiber strength and length notably better than high fiber quality cultivars used as checks and perform well across the US Cotton Belt. Both 13AFX6 and 13AFX13 are breeding lines developed from two unique sets of single crosses between upland cotton lines. These initial crosses were followed by individual plant selections in the F₂ and F₃ generations, and progeny row selection in the F₄ generation. The F₄ selections were grown in replicated tests at College Station, TX, and Florence, SC, in 2017 and 2018. The two best unrelated lines from these evaluations were grown in the Regional Breeders Testing Network in 2019. In this trial, 13AFX6 had significantly higher fiber strength and fiber length than other entries in the test. 13AFX13 also had excellent fiber strength and length, significantly higher than the checks used in the trial. Both lines had lint yields equivalent to the DP493 and FM958 checks. The outstanding fiber quality traits and good yields make 13AFX6 and 13AFX13 excellent choices to use as parents to incorporate fiber quality into cotton breeding programs.