GENERAL AND SPECIFIC COMBINING ABILITY ON SEED QUALITY OF S3 MAIZE INBRED LINES

Abstract

Analysis of diallel crosses is an important tool to determine the genetic effect in studies of seed quality of maize (Zea mays L.). The objective of this research was to determine the genetic component of general combining ability (GCA), specific combining ability (SCA) and reciprocal effects (ER) involved in the expression of seed quality and seedling vigor of S₃ lines, as well as of their direct and reciprocal crosses. The F₁ crosses and their parents were submitted to analytical tests of physical quality as seed biomass and seed physiological quality by standard germination, germination speed and vigor by accelerated aging. Additionally, an assay was developed in sand as a substrate for recording in seedling emergence, seedling height, shot dry biomass, vigor index I and II. A complete randomized blocks design with three replications was used in laboratory and with two replications in the evaluation in the sand bed. Statistically significant differences between genotypes were found in seed quality and seedling vigor. A similar situation occurred for GCA, SCA and RE in both groups of the evaluated traits, where ACG was predominant over SCA. Significant reciprocal effects showed the importance of properly selecting the female parent to promote the seed quality and seedling vigor. The crosses with high heterosis for these characters had at least one high GCA inbred line, and SCA effects were high and positive. Maize lines TNM-5 and TNM-4 showed high GCA and high SCA in specific superior combinations; thus they might be used in breeding programs: first for selection to increase the additive genetic frequency on seed quality and seedling vigor, and later they might be used in hybridization programs.