Punjab Agricultural University, Hissar
*Present Address: Institute of Advanced Studies, Meerut University, Meerut, INDIA.
Online published on 25 January, 2012.
Six populations, namely P1, P2, F1, F2, B1 and B2 of eight different crosses involving parents; 320 F and AC 138 (local strains) used as females and SA 267 (U.S.A.), 108 F (U.S.S.R.), AC 134 (Pakistan) and 5143 C (Ceylon) used as males, were studied for estimating the nature and magnitude of genetic variances, heritability and genetic advance for 6 yield characters in upland cotton (Gossypium hirsutum L.) under two dates of sowing at the University farm Hissar during the year 1968–69.
The character means for the 38 different progenies varied under two dates of sowing. Generally the F1 recorded higher values than parents. The progenies derived from the cross AC 138 × 5143 C and AC 138 × AC 134 in the different generations, i.e., F1; F2, B, and B2 had the highest average yielding ability. The estimates of genetic variances and gene effects showed that all the three types of gene action and the variances arising due to them, i.e., additive, dominance and epistasis were present in varying proportions for the six characters of all the eight crosses studied. The variance estimates indicated relatively-higher magnitude of additive variances for yield. However, the dominance variance was also important in several crosses. The component characters of yield similarly showed varying proportion of additive and dominance variances. Among the epistasis effects, the additive × additive and dominance × dominance interactions were more common for most of the characters. In many cases the dominance × dominance interactions were negative and thus had depressing effect on the character. Moderate to very high heritability estimates were obtained for all the six yield characters. The estimates of expected genetic advance followed the trend of heritability estimates.
Considering the nature and magnitude of genetic variances it was proposed that segregating generations may be created by multiple crossing involving generally diverse parents and further intermating the superior segregates in early generations; practising recurrent selection in such populations would allow most efficient utilization of the prevalent gene action.
