HETEROSIS AND PRODUCTION OF HYBRID SEEDS OF COTTON ON THE BASIS OF CYTOPLASMIC MALE-STERILITY IN CROSSES OF GOSSYPIUM-HIRSUTUM L X GOSSYPIUM-BARBADENSE L

An androsterile cotton strain of American origin with a cytoplasm from C. harknessi has been studied for the first time under conditions in Middle Asia. Sterile analogs of six early-maturing strains of the upla nd cotton G. hirsutum have been produced and their combination ability has been studied. Four strains have been isolated from the Egyptian c otton G. barbadense, which partially recovered fertility. Thus, all co mponents have been obtained, which are essential for mass production o f cotton seeds on the basis of cytoplasmic male sterility. The obtaine d androsterile analogs of the upland cotton strains with a high combin ation ability can be used as maternal forms for production of heterosi s-interspecific hybrids on the sterile basis. The developed method for evaluating the degree of cotton plant sterility, based on the ratios between flowers with sterile, semi-sterile, and fertile pollen as assa yed for 100 plants in randomized samples, is recommended for studying the cytoplasmic male sterility in this culture.