Introgression of day-neutral genes in primitive cotton accessions: I. Genetic variances and correlations

Abstract

Many of the primitive accessions of cotton, Gossypium hirsutum L., are photoperiodic and not readily useable by plant breeders. Five generations of day-neutral progenies (F5, BC1F5, BC2F5, BC3F5, and BC4F5) derived from 16 accessions crossed to 'Deltapine 16' were evaluated for agronomic and fiber traits for 3 yr. Genetic variance components for each trait and correlation among these traits were studied. Variation of accession generation was highly significant for all traits studied. Main effects for accessions and generations were significant; however, the magnitude was relatively small compared with the interaction variation. The breeding merit of day-neutral progenies should be evaluated according to specific accessions. Lint yield had significant but small positive phenotypic correlation with lint percentage, boll size, and 2.5% span length, but not with the other traits studied. Highly significant positive correlations were found for effects of accession, generation, and accession x generation between lint yield and lint percentage. With the use of multiple backcrosses to introgress day-neutral genes in primitive cotton accessions large interaction can be expected between accession and backcross generation; therefore, specific generations should be evaluated for the trait of interest.