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Determination of Yield, Yield Components, and Fiber Properties as Influenced by Selective and Nonselective Samplings¹

We compared two methods of sampling cotton (Gossypium hirsutum L.) at Stoneville and Scott, Miss. We used 14 of the cultlvars from the 1971 regional high quality test. Each entry was replicated four times at each location, with two-row plots, 16-m long and l-m wide. In the selective-sampling method, individual samplers picked 75 bolls from throughout the plot. For nonselective samples, all bolls were counted and harvested from two random areas (about 0.8 m of row) in the plots. The samples from the first two replications and the last two replications were bulked to form two composite samples at each location.

Selective sampling resulted in the computation of higher yields (4.4%), lint percentage (4.4%), boll size (15.2%), seed index (2.5%), lint index (10.0%), and seeds/boll (9.5%), and a lower number of bolls/ha (12.8%). Interactions of sampling methods and locations were significant for yield, bolis/ha, lint percentage, boll size, lint index, and seeds/boll. Cultivar by sampling method interactions were significant for yield, bolls/ha, and boll size, and three factor interactions were detected for seed index, lint index, and seeds/boll. Although these interactions were small compared to that for cultivar, they do imply that selective sampling causes cultivar misevaluation.

As a result of selective sampling, yarn strength, 50% span length, 2.5% span length, length uniformity, reflectance, yellowness, and micronaire were 1.6, 2.8, 0.0, 3.3, 2.8, 0.1, and 8.0% higher, respectively, than that of the nonselective samples. Sampling by location interactions were detected for 2.5% span length, reflectance, and yellowness.

There are implications for genetic evaluations.

Key Words: Variety evaluation • Genetic analysis

² Research geneticist, USDA, ARS, delta branch of the Miss. Agric. and For. Exp. Stn., Stoneville; laboratory director, USDA, ARS, cotton quality labs., U. of Tenn., Knoxville,; and plant breeder, delta branch of the Miss. Agric. and For. Exp. Stn., Stoneville, MS 38776, respectively.

Received for publication December 12, 1974.