A Diallel Analysis of Several Fiber Property Traits in Upland Cotton (Gossypium birsutum L.) II1

Diallel analyses of upper 2.5% span length, micronaire, 1/8‐inch gauge stelometer, and 0‐inch gauge stelometer were conducted on 10 selected varieties of upland cotton, Gossyplum hirsutum L., the 45 possible F1 crosses among them, and their 45 F2 progenies using the procedure of Jinks and Hayman. A partial failure of the basic assumptions of the analysis was noted for each trait though the stelo meter measurements more nearly fulfilled the assumptions than did length or micronaire. Fiber length and strength appeared to be governed by a weighted overall degree of dominance that was partial in nature. The degree of dominance for micronaire appeared to be in the overdominance range. Based on the relative size of their heritability estimates, mass selection should be an effective breeding method for improving fiber length and strength in this material though it should be slightly more effective for strength than for length. Pedigrees, sib tests, and/or progeny tests may be necessary to improve micronaire. The reliability of diallel estimates made on F1 populations from one year to the next at the same location was studied. Comparisons between F1 and F3 estimates were also made. Specific similarities and differences are discussed in the body of this paper.