Assessment of Combining Ability for some New White Maize Inbred Lines (Zea mays L.) Using Line X Tester Model

This research was conducted with the aim of assessment of the combining ability for yield and yield components in some new white maize. To achieve this goal, nine new white maize inbred lines were derived from different sources crossed to three testers; Sd.34, SC.10, and SC.131 at Ismailia Agricultural Research Station during the 2021 growing season. In the 2022 growing season, 27 topcrosses in addition to two commercial check hybrids; SC.10 and TWC.321 were evaluated at three locations; Ismailia, Sakha and Sids Agricultural Research Stations. The results cleared that highly significant differences were found between the three locations for all studied traits except no. of rows ear^-1 and no. of kernels row^-1.  Mean squares due to crosses, their partitions and their interaction with locations were significant or highly significant for most of the studied traits. Three inbred lines; Ism.7246, Ism.7316, and Ism.8094 were possessed the best general combiners for grain yield (GY), ear length (EL), no. of rows ear ^-1 (RE^-1) and no. of kernels row^-1 (KR^-1).  The results showed that significant positive GCA effects for grain yield (GY ard fed^-1) were highly correlated with those that had significant positive GCA effects, indicating that the line with high GCA effects for GY, generally had high GCA effects for YCTs with high GCA effects. Thus, selecting inbred lines with positive GCA effects in either all or most of the YCTs will have a greater chance to produce crosses with the ability to give higher grain yield. The histogram can show any inbred line with positive or negative GCA effects for GY and the YCTs GCA effects directly, then the inbred line Ism.7246, Ism.7316, and Ism.8094 had positive GR ratio values for all studied traits. On the other hand, the inbred line, Ism.7280 had negative GR ratio values for GY and YCTs GCA effects. The maize crosses (Ism 7246 x SC 10), (Ism 7316 x SC 10) and (Ism 7316 x SC131) increase significantly outyielded the check TWC 321. This indicates the importance of these white single- and three-way crosses as promising genetic material for high yield potential in future programs in maize breeding.