Combining ability and heterosis studies in cotton (Gossypium hirsutum L.) for yield and fibre quality traits

Cotton is India's most important cash crop and it is used for agricultural and industrial purposes for all over the world. The greatest way for identifying superior hybrids and best combiners of parents is by L*T design. For analyzing the combining ability and heterosis for various yield attributing variables as well as quality traits, the parents viz., four lines and four testers were crossed to produce sixteen hybrids. MCU5 * KC3 cross contributed to positive, highly significant heterosis for the traits viz., the number of sympodial branches, lint index and the number of bolls per plant, along with highly significant values of sca for the traits viz., the number of sympodial branches, seed cotton yield per plant and micronaire. CO14 * NDLH1938 had a highly significant sca effect for the trait of upper half mean length along with significant heterosis for the traits, viz., boll weight and seed cotton yield per plant. Therefore, MCU5 had the best gca value for the upper half mean length among the four lines. The KC3 tester had a high gca value, indicating that it contributes to additive genes among the four testers. For some traits, not all good combiners have good sca effects. In the majority of the qualities investigated, non-additive or dominant gene action was seen. Heterosis breeding can be used to exploit the amount of available vigour.