NOTICE OF RELEASE OF THREE ARKOT S23 GERMPLASM LINES OF COTTON

摘要

The Arkansas Agricultural Experiment Station announces the release of three noncommercial breeding lines of cotton, Gossypium hirsutum L., designated as Arkot S23-1, Arkot S23-2, and Arkot S23-4. The primary breeding objective associated with these lines was to develop near-commercial lines from a non-traditional germplasm source. The three lines were derived from a mixed population of germplasm developed by J. M. Stewart. A synthetic allotetraploid was made by hybridization of G. arboreum A2-026 andG. armourianum followed by doubling of the chromosome number with colchicine. The synthetic allotetraploid was crossed with G. hirsutum ‘Hancock’ and the trispecies hybrid was self-pollinated. Various morphological selections and open-pollinated bulkpopulations were grown for eight generations in a genetic nursery at Fayetteville, AR (area with high outcrossing). During the 8-year period the nursery contained other cultivars of G. hirsutum, multiple selections from the trispecies hybrid, and other interspecific hybrid combinations, especially involving G. herbaceum. Genetic diversity within a line was maintained each year by bulk harvesting a boll from each plant without selection. Beginning in 1995 seeds from nine lines derived from the original trispecies hybrid were bulked, and one-cycle of mass selection was performed on an isolated population at the Main Experiment Station at Fayetteville, AR. A second-cycle was employed in a planting at Southeast Branch Station at Rohwer, AR (area with low outcrossing) in 1996. Bolls were only harvested from plants possessing plant stature, fruiting, and lint color characteristics consistent with commercially grown cotton. Forty individual plants (designated at S1 through S40) were selected from the segregating population at Rohwer in 1997, and evaluated as progeny rows at two Delta locations in 1998. Nineteen of the 40 were selected and evaluated as advanced progeny in 1999 and 2000. In 2000, 54 individual plant selections were made from four (S03, S08, S21 and S23) of the progeny. Arkot S23-1, Arkot S23-2, and Arkot S23-4 were three of the 15 plants selected from the S23 progeny.