This investigation was undertaken during three successive summer seasons to study the combining ability of some traits of maize and their interactions with growing years A half diallel set of crosses Involving seven inbred lines were evaluated in this study. Significant year mean squares were detected for all of the studied -characters except for number of rows/ear, plant height, and silking date. Significant mean squares of crosses for all traits were obtained in both seasons as well as the combined analysis. Also, appreciable crosses by year interactions were detected for all characters. Significant g.c.a. and sca. variances were obtained (or most of the studied trait in both seasons and the combined data. The additive genetic variance was predominant in the inheritance of ear diameter and plant height, whereas non-additive gene effects were prevaiLing for grain yield) plant and number of grains/row in the three studied cases, Significant interaction effects between both general and specific combining ability and planting dates were detected for grain yieldlplant. Number of rows/car, number of grains/row and plant height. The parental line MR4 seemed to be the best combiner for grain yield/plan;. ear length, and siLking date. Inbred line MRS was the best combiner for car diameter and it was among the best combiners for grain yield/plant and ear length. The highest desirable s.c.a. effects were recorded in the crosses. (K 64 x G 224 0) for grain yield/plant and ear diameter, (G 224 D x MPS) for ear length, (G 507 A x MR5) for number of rows/ear,(0251 B xMR5) for plant heiglit. (G 507 Ax K64)for ear heighl, and (G 307 A x G 251 B) for silking date. The increases in grain yield/plant relative to D.C. 204 (35.2r/0 and 30.08%) were detected for the cross (G 507 A x MPS) in the first season and the combined analysis. respectively. |
