Diallel analysis of maize lines as to their phosphorus responsiveness and use efficiency

Abstract

The objective of this work was to evaluate additive and nonadditive genetic effects on P use efficiency and responsiveness to the nutrient in maize lines. Nine contrasting inbred lines – efficient or not regarding 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 L3 and L228‑3 lines showed the highest average effects for general combining ability (GCA, ĝi), indicating use efficiency in the absence of P, and responsiveness, in the presence. The L51502020 x L22 and L36 x L56.800.84 crosses had the highest average effects for specific combining ability (SCA, ŝij) in the presence and in the absence of P, respectively. The quadratic components for GCA were higher than those for 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