Relationship between heterosis, potence ratio and genetic distance for yield traits in maize (Zea mays)

An experiment was conducted during 2014-18 at Agricultural Research Station, Professor Jayashankar Telangana State Agricultural University, Karimnagar, Telangana to find out the relationship between heterosis, potence ratio and genetic distance for yield contributing characters in maize (Zea mays L.). Heterosis was trait dependent exhibiting high level for plant height, ear height, ear length, kernels/row, 100-kernel weight, grain yield and fodder yield. Two hybrids BML-51 x BML-14 (22.1%) and BML-51 x BML-6 (13.2%) recorded heterosis of greater than 10% over the check NK6240 and exhibited negative heterosis for flowering and maturity traits and positive heterosis for the remaining traits. Potence ratio indicated that majority of the traits in the hybrids had over dominance gene effect and expressed over dominance for ear length, ear diameter, kernels/row, fodder yield and grain yield suggesting heterosis breeding is an appropriate strategy for improvement of these traits. Standard heterosis of greater than 5% was observed in 7 crosses and out of these 6 belonged to mid parental divergence group. Five crosses, viz. BML-51 x BML-14, BML-51 x BML-7, BML-51 x BML-6, BML-32 x BML-13 and BML-32 x BML-6 with yield ranging from 7637 to 8733 kg/ha belonged to the medium parental divergence group comprising of high yielding inbreds, viz. BML-51 or BML-32 as parents. Grain yield heterosis was found significant and positively correlated with heterosis for ear length and 100-kernel weight. Therefore to maximize the full genetic potential of hybrids, inbreds with high per se performance and intermediate genetic divergence are to be involved in maize crop improvement programmes.