|Boykin jr, James|
Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 6/12/2004
Publication Date: 6/12/2004
Citation: Boykin Jr, J.C., Creech, J. 2004. Comparison of conventional and breeder sample methods for fiber quality parameters. In: Proceedings of the National Cotton Council Beltwide Cotton Conference, January 4-6, 2004, San Antonio, Texas, CD ROM p. 2951-2964. Interpretive Summary: U.S. cotton production typically exceeds 15 million bales per year, much of which is exported. It is important that the quality of this cotton keeps up with the changing demands of industry. New varieties are developed each year with improved fiber properties and increased yield. As these varieties are developed and marketed, it is important to accurately characterize fiber yield and other fiber quality parameters in tests designed for variety selection. Most cotton variety tests are limited to small plots, and sampling methods are limited by the size of these plots. Small samples are usually gathered by hand or machine to test in laboratory gins. It is important that the results of these tests agree with actual crop results. This paper presents results of a test which compared small hand-picked samples taken randomly from plots to whole-plot machine harvested samples. Hand-picked samples were ginned on a small laboratory gin, while the machine harvested samples were ginned through a conventional ginning sequence. Lint yield and other fiber quality parameters were determined for each sample method. The differences observed between the two sample methods reflect both differences in picking and ginning. There was a good relationship between methods for gin turnout (lint percent), fiber length, micronaire, strength, reflectance, and seed index, but care should be used in predicting conventional results from hand-picked bolls using this sampling method. There did not seem to be much comparison between the microgin and hand-picked boll samples for uniformity, yellowness, leaf, or lint value. Thus, care must be exercised in translating data from lab results to commercial applications.
Technical Abstract: Two methods for sampling cotton variety trial plots were compared in this test on 38 varieties grown in an early maturing variety test and 27 varieties grown in a medium maturing variety test. Hand picked samples, consisting of 25 randomly chosen bolls from each plot, were taken before picking the entire plot by machine. The samples picked by hand were ginned on a laboratory saw gin and the whole-plot samples were processed through the microgin. All properties were more precise for the microgin samples than for the hand-picked boll samples. Gin turnout, micronaire, uniformity, fiber length, strength, and seed index were overestimated by hand-picked boll samples, while reflectance, yellowness, leaf, and price were underestimated by hand-picked boll samples. There were good correlations between the microgin and hand-picked boll sample data for gin turnout (lint percent), fiber length, micronaire, strength, reflectance, and seed index, but care should be used in predicting conventional results from hand-picked bolls using this sampling method. Only large differences seen in hand-picked boll samples should be expected in machine-picked, conventionally ginned samples. Conventional results may be better predicted by using an improved protocol for hand-sampling. There did not seem to be much comparison between the microgin and hand-picked boll samples for uniformity, yellowness, leaf, or lint value.