Zziwa Simon^{1, 2,}, Lwanga Charles Kasozi², Rubaihayo Patrick¹, Muwonge Abubaker²

Combining ability of inbred lines is crucial information in maize hybrid breeding programs incorporating materials from various germplasm sources. This study was conducted to assess the gene action for grain yield and other agronomic traits for germplasm having varying resistance to Striga hermonthica and genetic. In a half diallel cross of ten parents, general and specific combining abilities for grain yield, plant and ear height, plant and ear aspect, ears and plants harvested, ear rot, husk cover, moisture and resistance to Striga hermonthica were determined. The grain yields of the single crosses were significantly higher for 1368STR x TZISTR1198, TZISTR1132 x CML442, TZISTR1174 x TZISTR1198 and TZISTR1199 x TZISTR1174. The importance of both GCA (50%) and SCA (50%) for grain yield, ear rot, ear texture and ears harvested were observed, but a preponderance of GCA was existed for AUSNPC, whereas plant and ear height, plant and ear aspect, and moisture content exhibited preponderant SCA. TZISTR1174, TZISTR1162, TZISTR1192, and CML442 were good general combiners for grain yield showing highly significant positive GCA effects of 0.40, 0.2, 0.17, and 0.22, respectively while lines TZISTR1199, TZISTR1192, TZISTR1174 and TZISTR1162 were good general combiners for resistance to Striga showing highly significant negative GCA effects of-646.99,-428.21,-338.00, and-76.51. These inbred lines could be exploited in hybrid breeding to develop high yielding Striga resistant maize varieties. Hybrids such as TZISTR1174 x CML312, TZISTR1192 x CML442and TZISTR1174 x 1368STR had significant positive SCA effects for grain yield whereas crosses like TZISTR1162×TZISTR1198, TZISTR1199×TZISTR1181, TZISTR1192×1368STR had highest negative significant SCA effects of-1453.19,-1058.28, and-808.252 for AUSNPC which can be used for direct production as single cross hybrids or developed further as three way cross hybrids.

gene action, combining ability