COMBINING ABILITY OF EIGHT WHITE MAIZE (Zea mays L.) INBRED LINES FOR GRAIN YIELD AND OTHER TRAITS IN DIALLEL CROSSES

Abstract

All possible combinations were made in 2005 season between eight diverse white inbred lines of maize in a half diallel at Gemmeiza Agric. Res. Station to obtain 28 single crosses. The 28 F1,s and one check were planted at three locations i.e. Sakha, Gemmeiza and Sids Agricultural Research. Stations in a randomized complete block design, with four replications, in 2006 summer season. Combined analysis of variance for the three locations was performed for number of days from planting date to 50% silking emergence, plant height, ear height, ear position %, stand %, ear length, ear diameter, no. of rows/ear, weight of 100-kernel and grain yield. Estimates of combining ability effects according to Griffing (1956) Method-4 Model-1 were determined. The results could be summarized as follows: Significant differences were found between the three locations for all studied traits except for Stand % and no of rows/ear. Both additive and non additive gene actions were found to be important in controlling for all studied traits except for additive gene action for weight of 100 kernels. However, the additive gene action seemed to be more important than the non additive gene action in the expression of silking date, plant height, ear position%, ear length, ear diameter, no. of rows/ear and grain yield. While, the non additive gene action was more important in the inheritance of ear height, stand% and weight of 100 kernels. The interaction between locations with both types of combining ability was detected significant for most of the studied traits. However, the additive gene action was more affected by the environment than the non additive gene action for all studied traits, except for ear height, ear position%, stand% and ear length traits. The best combiners for GCA effects were the parental inbred line; P1 for grain yield, ear position%, ear diameter and no. of rows/ear; P3 for grain yield, weight of 100 kernels, silking date (toward earliness), ear height and ear position% (toward low ear placement); P5 for plant height and ear height (toward shorter plants low ear placement) and stand%; P6 for grain yield, stand% and ear length; P7 for grain yield and no. of rows/ear. The four crosses i.e., (P1 x P4), (P1 x P5), (P3 x P7) and (P6 x P8) had desirable SCA effects for grain yield and exhibited significant superiority over the commercial SC-129 hybrid for grain yield, ear diameter and no. of rows/ear. These crosses could be used as good hybrids in maize breeding program.