GENERAL AND SPECIFIC COMBINING ABILITY FOR AGRONOMIC TRAITS IN PARTIALLY INBRED LINES OF MAIZE (Zea mays L.)

Abstract

Knowing the type of gene action that controls agronomic traits is essential for the planning and development of a maize genetic improvement program. The objective of this study was to determine the genetic components of general combining ability (GCA), specific combining ability (SCA) and reciprocal effects (ER) involved in the expression of agronomic traits in a set of S3 maize lines. F1 crosses and their progenitors were evaluated at two planting dates: March 18 and May 28, 2014. The following agronomic traits were recorded: plant height, days to male and female flowering, days to physiological maturity, general appearance of the plant, crop yield and some of its components.  Statistical differences were found between genotypes for all the traits in the two planting dates. Regarding the effects of GCA and SCA, significant differences were found for all the traits, with a predominance of GCA on SCA for days to male and female flowering, days to physiological maturity, plant height and yield. However, the most important component regarding general appearance of the plant and crop yield was SCA. The ER were significant in plant height, days to female flowering and general appearance of the plant. TNM-5 and TNM-4 lines showed high GCA in yield and its components, and greater precocity. In crosses with high and positive estimators in all the traits evaluated, lines with high ACG estimators and with low and negative effects intervene.