|CALHOUN, STEVE - DELTA RESEARCH & EXT CTR
|WALLACE, T - MISS. STATE UNIV.
|BARFIELD, M - STONEVILLE PEDIGREED SEED
Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 6/3/1996
Publication Date: N/A
Interpretive Summary: In small-plot cotton research, sub-samples of seed cotton are collected and ginned on small laboratory gins to determine lint fraction and fiber properties. How results from these sub-samples relate to large samples processed through a commercial ginning sequence is not known. The objectives of this study were to: 1) determine if, and by how much, lint fraction and fiber quality results from hand- and machine-harvested sub-samples differ from results obtained from large samples processed through a commercial gin sequence, 2) determine if there is a significant interaction for lint fraction and important fiber traits, and 3) compare the precision of different sample methods. Results indicated substantial differences for some traits; for example, lint fraction was 5 percentage points lower from whole plots samples than from selected sub-samples from harvest of the entire plot. Thus, if relative differences among varieties rather than actual values are of primary interest, choice of sample method should be governed more by logistical considerations rather than concerns about the quality of the data. If actual values are of primary interest, sub-samples from the entire harvested plot are preferred. Findings in this study should make research results more applicable for commercial use and improve their reliability.
Technical Abstract: This study was conducted to clearly define the fiber quality and yield relationships between small plot research and field trials. The specific objectives were to: 1) determine how much lint fraction and fiber quality results differed between hand-harvested sub-samples, machine-harvested sub- samples and entire samples processed through a commercial gin sequence, 2) determine if there is a significant genotype x sample method interaction, and 3) compare the precision of the sample methods. Three types of samples were collected. Sample methods were: 1) 100 random bolls hand-harvested prior to mechanical harvest (boll samples, BS), 2) 400-600 sub-samples from machine harvested samples (grab samples, GS), and 3) remainder of seed cotton (25 to 60 lb. per plot) (whole plot samples, WP). BS and GS were ginned on a 10-saw laboratory gin; WP was ginned through a commercial ginning sequence on the USDA-ARS 20-saw microgin at Stoneville, MS. Lint fraction was 5 percentage points lower from WP than from BS or GS. Fiber length from WP was 0.03 in shorter than GS, and 0.05 units lower than from BS, but only 0.04 units lower than from GS. As long as relative differences among test entries, rather than actual values, are of primary interest, choice of sample method should be governed more by logistical considerations (e.g. labor, cost, and time) rather than concerns about the quality of the data. If actual values are of primary interest, GS would be preferred.