Investigation of maize hybrids based on direct and reciprocal crosses

Introduction In maize selection, it is of great importance to know the performance and combining ability of crossing partners. It is also relevant in seed production and basic research to study differences between single and reciprocal crosses. A few Hungarian literature references draw attention to this field (Berzy et al., 2005). Kovacs (1963) investigated direct and reciprocal single crosses derived from Martonvasar lines and found no difference between the productivity of the two hybrids. Transposition of parents can be accounted by the fact that the cytoplasm of certain lines does not take part equally in the development of agronomical features. With the transposition of parents, more economical seed production can be obtained (Nagy, 1982). Nagy (1985) examined leaf number, ear height, ear length, cob weight, kernel line number, ear weight, kernel weight, 500 kernel weight, shelling % and oil content in 14 early SC hybrids and their reciprocal variety. In one quarter of compared data pairs, significant difference was found at P≥5%. Hegyi (2001) studied protein and oil contents of 12 direct and 12 reciprocal hybrids and found no heterosis coupled to parental average. In 10 cases there was significant difference in protein content, while no statistical difference was found in oil content between direct and reciprocal hybrids. Plant height and height of main ear were examined by several authors (Gyenesne Hegyi et al., 2002, 2005a, b; Zsubori et al., 2001) and they concluded that one of the most important phenomena was the close relation of trait pairs to other characteristics. Khehra and Bhalla (1976) crossed 10 genetically different maize lines among them reciprocals. They observed larger difference in point of reciprocal effect in early x late variety combinations rather than in early x early or late x late ones. According to Pollmer et al. (1978) it is hard to utilize the commercial value due to instability and low magnitude of reciprocal differences, however in their studies they showed difference in almost all traits. This information is important during the prediction of breeding basic material. We can obtain a few data from the literature about tassel characteristics in direct and reciprocal crosses.