Combining ability of maize lines derived from CIMMYT germplasm in crossing with temperate lines

Twenty eight crosses of four temperate maize testers (MO17, K18, K166B and A679) with seven lines originated from CIMMYT germplasm were evaluated using a randomized complete block design with three replications, at seven locations (Karaj, Shiraz, Dezful, Jiroft, Moghan, Gorgan and Kermanshah), Iran, in 2012. In 2013, number of lines were increased to 13, and 52 crosses were obtained with the same testers as in 2012. Hybrids No. 28 (XT02 ×K166B), 10 and No. 23 had 10.160, 9.867 and 9.822 t.ha-1 grain yield, respectively, that revealed to be of high yield potential hybrids. Combined analysis of Line ×Tester showed no significant differences between lines and testers, but significant line × tester interaction effect was observed. Significant general combining ability (GCA) effects were obtained for the four testers, but none of the lines showed significant GCA. Results showed the possibility of germplasm enhancement in temperate maize program, using CIMMYT germplasm (tropical and subtropical), especially those sources produced under similar conditions as Iran (such as CIMMYT program in China). This experiment revealed that crossing these germplasm with temperate maize germplasm prior to selfing, has no significant effect on derived lines. Using more sources, as well as testers, from each group is necessary to facilitate the success in development of adapted maize germplasm.