The estimation of genetic parameters such as heterosis (Mh), heterobeltiosis (Hh), general combining ability (GCA) and specific combining ability (SCA) allows inferences about the predominant action of the genes, indicates the appropriate selection strategy, and facilitates identification of the best parents. The present study was carried out using a diallel cross system among five genotypes of ... [Show full abstract] Triticale (x Triticosecale Wittmak). Genotypes CIMMYT 829 (G1), CIMMYT 830 (G2), CIMMYT 834 (G3), CIMMYT 820 (G4) and Antonio UNLPam (G5) were crossed in a complete diallel combination without reciprocal crosses, in La Pampa, Argentina. The additive genetic effects were of greater importance than the nonadditive ones for the following traits: spike length (SL), days to anthesis (AD), spikelets per spike (SS); grains per spike (GS), 1000-kernel weight (1000-KW), grain yield (GY), test weight (TW) and harvest index (HI). The G1 and G4 parents showed better GCA for GY, HI, 1000-KW and SL indicating a greater contribution of additive gene action and a promising feature to obtain prominent recombination lines. The G1xG4 cross showed Hh and a significant SCA value for GY, indicating a greater contribution of the non-additive gene action, useful to develop hybrids.