Heterosis and production of hybrid seeds of cotton on the basis of cytoplasmic male sterility in crosses of Gossypium hirsutum L x G-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 upland cotton G. hirsutum have been produced and their combination ability has been studied. Four strains have been isolated from the Egyptian cotton G. barbadense, which partially recovered fertility. Thus, all components have been obtained, which are essential for mass production of cotton seeds on the basis of cytoplasmic male sterility. The obtained androsterile analogs of the upland cotton strains with a high combination ability can be used as maternal forms for production of heterosis-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 assayed for 100 plants in randomized samples, is recommended for studying the cytoplasmic male sterility in this culture.