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Segregating populations were developed to evaluate the inheritance of the fiberless seed phenotype of upland cotton (Gossypium hirsutum L.) line SL1-7-1. We report the inheritance of fuzzy, fuzzless and fiberless seed from crosses of SL1-7-1 with wildtype DP5690, Mexican fuzzless seed UA 3-3 (accession 143), Ballard fuzzless seed (accession 243), and MD17. Results from the F1, F2 and F2:3 progeny derived from the SL1-7-1 X DP5690 indicated that the expression of the fiberless phenotype fit a three loci model with one locus being the dominant fuzzless seed allele N 1 . The other two loci were tested to verify whether they were allelic to either recessive fuzzless seed alleles n 2 or n 3 . Using the segregation ratios of the F2 progeny derived from the 143 X SL1-7-1 cross and F2-derived F3 families from SL1-7-1 X DP5690 with fuzzy seed (lacked N 1 ), it is proposed that SL1-7-1 lacks the recessive n 2 allele, but contains the n 3 allele in the genotype of SL1-7-1. The third locus was previously not characterized and has been designated as fl 1 (fiberless), therefore, the genotype for the fiberless phenotype of SL1-7-1 is N 1 N 1 fl 1 fl 1 n 3 n 3 . Fiberless lines MD17 X SL1-7-1 were crossed to verify similarities in genotypes between line and the genotype model predictability. Various combinations of the homozygous and heterozygous expression of N 1 , n 2 , n 3 and fl 1 allele produced plants with lower lint percentages.

Fifteen fuzzless seed lines in “obsolete” backgrounds of Upland cotton (Gossypium hirsutum L.) were obtained from the National Cotton Germplasm Collection and evaluated for fuzzless seed genotype, lint percent, and lint quality. Fourteen of these fifteen lines were found to be homozygous for the dominant fuzzless seed allele N 1. Only one line was homozygous for the recessive fuzzless seed allele n 2. The measured lint percent of each line was very stable through time, however, large variability existed between many of the N 1 lines ranging from 0.7 to 23.6% lint. The lint percent for the n 2 line was 24.4%. Scanning electron microscopy was used to differentiate patterns of lint initiation on 1 day post anthesis ovules. General patterns included: first, lint initiation restricted to the chalazal end of the seed crest; second, lint initiation along the seed crest and laterally around the chalazal end of the ovule; and third, lint initiation covered all but the micropylar end of the ovule. Lint quality was evaluated for each line using the Advanced Fiber Information System (AFIS) which included measurements of length, maturity, and fineness. The means of each measurement varied among the fuzzless seed lines with significant differences between fiber length, short fiber content, immature fiber content, fineness, and maturity ratio. No correlation was found between lint percent and any of the lint quality measurements. These lines will provide a valuable resource for the study of fiber initiation and lint quality.