A half diallel cross was made among eight white inbred lines of corn. The resulted crosses and check hybrid (S.C. G.10) were tested in both locations (Sakha Farm, Kafr EL-Sheikh Governorate and Somosta Farm, Beni Suif Governorate).
The aim of this study was to estimate the heterotic effects, general and specific combining abilities (GCA and SCA) and their interactions with locations. The studied traits were silking and tasseling dates, plant and ear heights, leaf area of ear, no. of rows/ ear, no. of kernels/ row, 100-kernel weight, shilling percentage and grain yield/ plant. The obtained results could be summarized as follows:
Location mean squares were significant for all traits, except for ear height and number of rows/ ear. Genotypes mean squares were significant for all traits. Significant genotypes × location mean squares were obtained for all traits, except shelling percentage. Significant parents mean squares were obtained for all traits. Significant interaction mean squares between parental inbred lines and locations were detected for all traits, except plant height and shelling percentage. For grain yield/plant, the parental inbred lines P5, P2 and P7 had the highest grain yield/plant. With the exception of inbred lines P1 and P6, all inbred lines gave the same grain yield/plant. These inbred lines exhibited high mean values for two or more of the traits contributing to grain yield. However, the parental inbred lines P1 and P6 gave the lowest ones for this trait. For grain yield/plant, fifteen parental combinations had significant superiority over check hybrid S.C. G.10. Fifteen hybrids surpassed the check variety by 16.39 to 75.35 % over the two locations. Also, the best heterotic effects were obtained for the crosses P5×P7(75.35), P1×P3(42.21), P1×P5(38.05), P1×P8(28.76), P3×P4(32.23), P3×P6(35.75), P3×P7(31.05), P4×P7(30.44) and P7×P8(33.42). The mean squares associated with general combining ability (GCA) and specific combining ability (SCA) were significant for all the studied traits. GCA/SCA ratio was estimated, it was found that all traits, except ear height, number of rows/ear, shelling percentage and 100-kernel weight, exhibited low GCA/SCA ratios of less than unity. On the other hand, high GCA/SCA ratio, which exceeded the unity, was obtained for the exceptional traits. The mean squares of interaction between location and both types of combining ability were significant for all traits, except shelling percentage. The parental inbred line P1 exhibited significant negative effects for tasseling. The inbred line P2 showed significant negative effects for plant height. The parental inbred line P3 showed significant negative effects for silking date and plant height and ranked the third best-inbred line for both traits.
The parental inbred line P5 seemed to be the best combiner for plant height and 100-kernel weight. Also, it showed significant desirable effects for ear height and grain yield/plant and ranked the second best inbred line for both traits. The parental inbred line P6 expressed significant desirable effects for, silking date, 100-kernel weight and tasseling date. The parental inbred line P7 behaved as the best combiner for, plant height, ear height, number of kernels/row, grain yield/plant and harvest index. The parental inbred line P8 exhibited significant desirable effects for tasseling date, silking date, leaf area, no. of kernels/row, 100-kernel weight, grain yield/plant and shelling percentage. The most desirable inter and intra allelic interactions were presented by P1x P4 and P5 x P7 for silking and tasseling date and P5xP7, P1xP3, P1xP5 and P3xP6 for grain yield/ plant.