A. Stoilova, I. Saldzhiev, Zh. Terziev

Abstract: Breeding of coloured cotton varieties will help to solve certain existing ecological problems concerning dyeing of yarn and tissues. In 2007-2009 competitive variety trials were conducted with brown cotton lines. The results obtained showed that, some of them in earliness and productivity were equal to the early and high yielding variety of white cotton Chipan-539. These lines are of great importance for developing of new cotton varieties with high economical and ecological effects in spite of their shorter fiber and lower lint percentage than those of standard cultivars. Some others (created later) had fiber length equal to that of check variety which reveals a possibility for enhancing the fiber quality of brown cotton trough breeding. Lines No 196 and 197 have commercial potential. Very valuable were lines No 105 and 106 with naked seeds, No 201 with naked seeds and natural early fall of the leaf. The variety Izabell is a new achievement in the breeding of a new generation varieties with an exclusive characteristic – naturally coloured brown lint. This variety had high productivity, earliness, suitableness for machine picking, medium fine and short fiber with high uniformity, good elongation and strength. In fiber length and some fiber length characteristics it was inferior to the standard cultivars – Chirpan-539 and Avangard-264. By the other technological fiber properties it was equal to the standards.