Abstract:
The objective of this work was to evaluate additive and nonadditive genetic effects on responsiveness and the P use efficiency by maize lines. Nine contrasting inbred lines - efficient or not regarding their P use efficiency - were evaluated in diallel crosses, in a randomized complete block design, for two years, under two availability levels of the nutrient in an Oxisol. The lines L3 and L228-3 showed the highest average effects for general combining ability (GCA, 
), indicating use efficiency in the absence of P, and responsiveness, in the presence. The crosses L51502020 x L22 and L36 x L56.800.84 had the highest average effects for specific combining ability (SCA, 
) in the presence and in the absence of P, respectively. The quadratic components for GCA were higher than those of SCA, in the absence of P, and lower in the presence, showing that the additive effects predominated in P use efficiency, and the nonadditive ones predominated in the plant responsiveness to the nutrient. The genotype combining ability interacted with the environments; therefore, the selection of the best parent and of the best hybrid combination should be done in specific environments. The inbred lines show genic complementary action regarding P use efficiency.
Index terms:
Zea mays; specific combining ability; general combining ability; genic complementary action; nutritional efficiency
