Registration of Arkot 9811 and Arkot 9815 Germplasm Lines of Cotton

Arkot 9811 (Reg. No. GP-919, PI 658215 and Arkot 9815 (Reg. No. GP-920, PI 658216) are noncommercial breeding lines of cotton (Gossypium hirsutum L.) that were released by the Arkansas Agricultural Experiment Station in October 2009. Arkot 9811 was derived from a 1998 cross of ‘FiberMax 989’and Arkot 9108. Arkot 9815 was derived from a 1998 cross of ‘GC-251’ and Ark 8717–17–13, an advanced breeding line that was derived from crossing two F₁ populations, one derived from crossing ‘DES 119’ and Miscot 7803–52 and the other one derived from crossing Miscot T8–27 and Miscot 8006. Lint yields of Arkot 9811 and Arkot 9815 were equal to two check cultivars in 15 Arkansas tests. Among the 32 entries evaluated in all 10 locations of a regional test in 2007, Arkot 9811 and Arkot 9815 produced the second and third highest lint yields, respectively. Basic yield and related yield components (number of seed per area, lint index, seed index, and fibers per seed) of Arkot 9811 were equal to those of ‘DP 393’. Arkot 9815 produced fewer seed per area, higher lint percentage, and fewer fibers per seed than DP 393. Height and maturity of both lines were similar to those of DP 393. Fiber properties of Arkot 9811 and Arkot 9815 were inferior to those of DP 393, producing higher micronaire and shorter length. Both lines produced moderate leaf pubescence ratings but were less glabrous than DP 393; however, the bract trichome density of both lines was less dense than that of DP 393. Both lines expressed resistance to bacterial blight. Arkot 9811 expressed resistance to tarnished plant bug equal to that of ‘SG 105’, while Arkot 9815 expressed higher resistance than either check cultivar. The relative yield, maturity, and line-specific host-plant resistance traits make these lines valuable to cotton breeding programs.