New 22 white inbred lines of maize were top crossed to two testers, inbred line Sd-63 and inbred line Sk-5 at Sakha Agricultural Research Station. The resulting top crosses and the commercial hybrid, SC10 as a check, were evaluated in a randomized complete block design trial with four replications at Sakha and Mallawi Agric. Res. Stations for number of days to mid silking, ear position, ear length, ear diameter and grain yield. The results of the present study at both locations could be summarized as fallows:
Mean squares due to lines, testers and their interaction were significant to highly significant for all studied characters, except testers, for grain yield at both locations and lines x testers for ear position at Mallawi and ear diameter for both locations.
The estimates of genetic variance indicated that the K2 GCA (additive genetic variance) was the most important component controlling the inheritance of days to mid silking, ear postion and ear diameter at both locations while the K2 SCA (or non-additive genetic variance) played the major contribution in the inheritance of grain yield and ear length at both locations.
The parental inbred lines, that revealed desirable GCA effects at both locations were Sk-5019/27 and Sk-5028/37 for earliness, Sk-5020/28, Sk-5037/43, Sk-5040/47 and Sk-5040/50 for ear position, Sk-5019/27, Sk-5025/33, Sk-5029/39 and Sk-5039/46 for grain yield, Sk-5019/27, Sk-5025/32, Sk-5029/38, Sk-5029/39 and Sk-5039/46 for ear length. The inbred line Sk-5 as a tester was the best general combiner for days to mid silking, ear position and ear diameter at both locations. While Sd-63 as a tester had the best GCA effects for ear length at both locations.
The best top crosses compared with check SC10 at both locations were, Sk-5019/27 x Sk-5, Sk-5035/40 x Sk-5 and Sk-5037/43 x Sk-5 for earliness, Sk-5037/43 x Sk-5 and Sk-5040/47 x Sk-5 for ear position, Sk-5019/27 x Sk-5, Sk-5025/33 x Sd-63 and Sk-5039/46 x Sd-63 for grain yield, Sk-5029/39 x Sd-63 and Sk-5039/46 x Sd-63 for ear length and Sk-5027/36 x Sk-5, Sk-5035/40 x Sk-5 and Sk-5040/48 x Sk-5 for ear diameter.