Genetic traits that reduce seedcotton trash and/or improve cleanability at the gin could improve lint grades and reduce the need for one or more lint cleaners. Fewer lint cleaners would reduce lint quality problems (neps, short fiber content, and reductions in lint turnout) associated with multiple stages of saw lint-cleaners. The objectives of this study were to determine the effects of open-canopy [sub-okra (L(u)), sea-island (L(e)), okra (L_o), and super-okra (L(s))], frego bract (fg), and semi-smoothness (t(3)) traits, alone and in selected combinations, on (a) the amount of trash before and after seedcotton cleaning, (b) the amount of lint trash and grade after processing through zero, one, and two saw lint-cleaners, and (c) seedcotton and lint cleanability.

The genetic materials consisted of eight near-isolines of LA 213-613 (LA 213-613-normal, LA 213-613-L(e), LA 213-613-L_o, LA 213-613-L(s), LA 213-6l3-t(3)ne, LA 213-613-fgne, LA 213-613-t(3)fgne, LA 213-613-L_ofgne) and four nearisolines of MD 65-11 (MD 65-11-normal, MD 65-11-L(u), MD 65-11-L_o, MD 65-11-L(s)). LA 213-613, an inbred line of 'Stoneville 213', has hairy, normal-shaped leaves and bracts, and nectaries. Isolines of this family have a coefficient of relationship of 96.1 to 96.9%. MD 65-11 is a nectariless (ne), semi-smooth strain of Deltapine 161. Isolines of MD 65-11 have a coefficient of relationship of 99.2%. The 12 isolines were grown under conventional cultural and pest management practices during 1986 and 1987 at three locations in Louisiana (Alexandria, Bossier City, and St. Joseph) in a randomized complete block design with four replications. Plots were harvested with a 2-row, spindle-picker after defoliation. To insure an adequate sample for ginning, the seedcotton at first pick from two replications in each environment was combined.

Seedcotton samples were transported to the USDA Cotton Gin Laboratory where they were allowed to condition for ca. 24 hrs at 24 C and 55% relative humidity prior to ginning. The samples were ginned on a cut-down (20 saws) version of a commercial gin (Continental Commander 20 saw-gin stand with 40.6-cm saws) under a controlled environment, constant feeding rate (0.34 kg seedcotton/minute/saw), and with zero, one, and two lint cleaners. The ginning sequence consisted of tower drier (56 C), cylinder cleaner (LuTamus), stick remover (Continental), tower drier (no heat), cylinder cleaner (Lummus), extractor-feeder (Continental), gin stand, and finally zero, one, or two saw lint-cleaners (Continental). Samples collected before (wagon) and after (feeder apron) seedcotton cleaning were use to determine the amount and type of seedcotton trash by the use of a pneumatic fractionator. Lint samples (duplicate 100g) collected after zero, one, and two lint cleaners were measured for amount and type of lint trash by the use of a Shirley Analyzer. An incline sieve (6-mm mesh) inside the trash chamber of the Shirley Analyzer allowed for the separation of motes and leaf/bract trash. Lint samples were graded by a licensed USDA cotton classer at the Rayville Classing Office and converted to grade index.

The semi-smooth trait was associated with reduced motes at the wagon, feeder apron, and zero lint cleaning; it was also associated with improved seedcotton small-leaf cleanability, and with reduced leaf/bract trash in lint at all stages of lint cleaning. Super-okra on the LA 213-613 background reduced motes at the wagon, feeder apron, and zero lint cleaning, and decreased the small leaf trash percentage at the feeder apron compared with normal leaf shape. Semi-smoothness and super-okra in the LA 213-613 background and sub-okra and super-okra in the MD 65-11 background ended with the same grade index after one lint cleaner as did their respective normal checks after two lint cleaners. The okra leaf and frego bract isolines had more small-leaf trash going to the gin (wagon) than the normal checks, but the differences disappeared after seedcotton cleaning. Frego bract isolines had less leaf/bract lint trash and higher grade indices than the normal-bract check after one and two stages of lint cleaning.