Punjab Agricultural University, Hissar, Haryana
**Present address:-Department of Genetics, Haryana Agricultural University, Hissar and Institute of Advanced Studies, Meerut University, Meerut (U.P.).
*Part of the thesis submitted to the Punjab Agricultural University in the partial fulfilment of the requirements for the degree of Doctor of Philosophy (Genetics) by R. S. Pathak.
Estimates of genetic variances and gene effects were made for yield and its component characters utilizing the six populations, i.e., P1, P2, F1, F2, B1 and B2 derived from crossing six diverse parents in upland cotton, Gossypium hirsutum L. PRS-72 a recent introduction from the U.S.S.R., which is a short fruiting branch, cluster boll bearing type strain, was used as common parent in crosses with the five normal fruiting branch type strains namely H 14 (Local standard), Res H141 (Reselection of H141), 419/49 (Abohar, Punjab), 5143C (Ceylon) and Banda I (Africa).
Dominance variance and dominance gene effects were much higher than additive variance and additive gene effects for seed cotton yield and boll number in the five crosses studied. The other component characters of yield usually exhibited proportionately larger estimates of additive gene effects. Epistatic gene effects were found for almost all the characters in all the crosses. Among the three types of epistatic gene effects, additive X additive and dominance X dominance effects appeared to contribute more to the different characters than the additive X dominance effects or even some of the estimates of main effects. In many cases the dd estimates were negative and thus had depressing effect on the characters. The more complex characters, as yield, showed larger dominance variance while the simpler characters, as the components, showed higher proportion of additive and a type of interaction.
