STUDY ON COMBINING ABILITY AND HETEROSIS IN MAIZE (Zea mays)

Abstract

Combining ability and heterosis were studied in (6x5)/2 half diallel cross with 6 parents in maize. The mean performances of different characters were separated by DMRT, where the highest yield/plant (186.6kg) was recorded from the cross P1×P2. Department of Genetics and Plant Breeding Farm, HSTU, Dinajpur during the period from November, 2014 to May, 2015. The experiment was set up in a Randomized Complete Block Design (RCBD) with three replication. The external expression of heterosisis the hybrid vigor. Heterosis was estimated over the better parent (heterobeitiosis) and average heterosis (heterosis over the mid parent) against of all the selected characters. Heterobeltiosis invariably is better than average heterosis but two parental contributions are equally beneficial than average heterosis may be considered. Among the 15 hybrids, two combinations like P1×P2 and P1×P3 showed positive and strongly significant heterobeltiosis for yield/plant, followed by other three combinations viz. P1×P2, P1×P3 and P1×P4. Therefore, three parental lines such P1, P2, P3 and P4 should be maintained generation after generation to ensure constant supply of parental lines in hybridization programs and in addition, the outstanding high yield potential above mentioned two hybrids may be advanced for commercial cultivation by the farmer’s of our country. The analysis of variance and analysis for combining ability indicated significant variation among the parents and hybrids for most the selected characters. Positive and significant GCA effects were shown by the parents like P1, P3 and P4 for yield/plant. The parents showing positive and significant GCA effects indicated high cross ability with all parents and genetic controlling of the characters predominantly would be additive. Out of 15 experimental hybrids, four crosses viz, P1 × P2, P1 × P3, P2 × P4, P3 × P5 exhibited positive and significant SCA effects for yield/plant due to exploitation of non-additive (dominance and/or epistasis) interaction of genes. Hybrid vigor is interaction output of non-allelic interactions, hence the four cross combinations invariably may be considered for improvement of yield in maize though hybrid breeding.