Many recent additions to the US Cotton Germplasm collection are uncharacterized for common germplasm descriptors.
Our objective was to evaluate a subset of this germplasm for their potential to contribute to future plant improvement efforts. One hundred fifty four cotton germplasm lines from the former USDA cotton breeding program at Shafter, California were evaluated in the field (LSU AgCenter Northeast Research Station, Saint Joseph, LA) in 2003 along with three modern commercial varieties (Delta and Pine Land �Deltapearl�, �Fibermax 958�, and �Phytogen 355�). Due to limited seed availability, an unreplicated modified augmented statistical design-2 was used, with single row plots 6.14 m long sown at a rate of 7-10 plants m-1. The following descriptors were considered: leaf and calyx pubescence; flower maturity; leaf, pollen and petal color; petal spot; glanding; presence of extra floral nectarines; bract shape. High volume instrumentation (HVI) fiber properties: length, strength, micronaire uniformity, and elongation; and cotton fiber yield. Eleven germplasm lines had yields within 10% the check average, with the top three highest yielding germplasm lines being SA 1961, 1962 and 1960 yielding 1635, 1477, and 1439 lbs acre-1, respectively. SA 2085 could be used to reduce insect damage since it was nectariless. There were 26 germplasm lines graded as having smooth leaves which could be used to reduce the ovipositing of bollworm eggs and get cleaner lint at harvest. In this germplasm, 66 % evaluated had long fiber and the top three were SA 2093, 1983, and 2091, with fiber lengths of 1.27, 1.26, and 1.25 inches, respectively. Much of this germplasm evaluated (82%) had very strong fiber and the top three were SA 2036, 2085, and 2044, with 40.5, 40.0, and 39.7 G/tex, respectively. Six germplasm lines had very high elongation and the top three were SA 2092, 1968, and 2069, with 8.4, 8.1, and 8.1 %, respectively. Over half of the germplasm evaluated (55%) had fine micronaire of between 3.8 and 4.6. In summary, these recent additions to the US Cotton Germplasm Collection present a valuable resource for improving cotton varieties with resistance to insects, yield and fiber quality.