Combining Ability and Heterosis in Diallel Analysis of Maize (Zea mays L.) Lines

Abstract

Combining ability and heterosis were studied in a 4 x 4 full diallel cross in maize for growth and yield contributing characters. Randomized Complete Block Design (RCBD) with four replicates was used to study the following research objectives: the general combining ability of parents, highly performed hybrids and heterosis of hybrids over commercial check variety for yield and its components. Genotype was highly significant for all the traits studied. The combining abilities (GCA and SCA) and reciprocal mean squares were highly significant for most studied characters. The ratio of GCA/SCA was not less than unity for studied traits excepted for days to anthesis and ear height. The results indicated that the additive genetic effects was more important and played major role in studied traits. Thus, results revealed GCA effects for four parental lines (PL), ‘PL2’ was excellent general combiner for number of tassels and cob circumference while ‘PL3’ was good combiner for days to silking and grain yield (t.h^-1). And ‘PL4’ for short height. A single cross hybrid from the GCA effects showed high SCA effects. However, most reciprocal effects were not desirable. Heterosis estimation was carried out using a commercial check variety, Oba super II. When commercial check was used, the percent heterosis for grain yield varied from -8.89 to 22.62%. Among the twelve F1 hybrid crosses, nine of the crosses exhibited significant positive heterosis for grain yield (t.h^-1). Those crosses that showed significant positive or negative desirable traits for SCA effects and significant positive heterosis could be used for varietal development.