ABSTRACT

For the past century, being the main cotton fiber supplier for the entire Former Soviet Union has caused many ecological problems in Uzbekistan due to extensive use of chemicals in cotton growing season, in particular chemical defoliants. Hence, to develop natural leaf defoliating varieties was one of the important targets of the cotton breeding programs in the Republic. Such a natural leaf defoliating line collection was developed using conventional breeding efforts, crossing wild diploid cottons with tetraploid varieties with consequent doubling chromosome numbers and selecting rare unique naturally early leaf defoliating tetraploids from the hexaploid cotton population. One of such examples is “Listopad Beliy” (white leaf defoliant) with very early leaf defoliating trait, which was developed from the cross between G. trilobum x G. harknesii and G. hirsutum. L.