Heterosis and combinatory aptitude in seven maize lines

This research was carried out to learn the performance of seven maize lines and their F, progenies. Germplasms were assessed in two trials during spring-summer 1997B to ear rot (ER), caused by Fusarium moniliforme and grain yield (GY). To estimate heterosis and its components, the Gardner & Eberhart (8) model II and Griffing (13) design 2 model I were applied. The estimated values of heterosis and its components, and those of GCA and SCA, show that in this work, Gardner & Eberhart (8) model was better in all estimations; with Griffing (13) design 2, the effects, principally SCA, were over estimated. The crosses 1x6 (AC8223-4-2-1-2 x 88-2-3-1-1) and 3x6 (AC7929-38-3-2-1 x 88-2-3-1-1), showed low ear rot percentage (18,01% and 14,09%). According to Jeffers's et al. (16) classification these crosses could be regarded resistant, and with acceptable grain yield (7,79 and 7,71 t ha(-1)), superior to the general mean of the experiment (5,18 t ha(-1)), but 0,62 t ha(-1) lower than the cross 5x6 (AC8149-5-1-2-1 x 88-2-3-1-1) that produced 8,33 t ha(-1). With the best crosses, it is possible to begin a breeding program for pedigree, to generate germplasm with resistance to ear rot and high grain yield.