Nitrogen use efficiency and phenotypic correlations of tropical maize populations in Tocantins

The objective of this study was to evaluate the nitrogen efficiency use and phenotypic correlation of 24 maize populations in Tocantins. Two experiments were conducted, each corresponding to a level of fertilization (high and low N) planted on 21/11/2009, treatments consisted of 24 populations obtained from the Maize Breeding Program of Federal University of Tocantins and a commercial variety, BR 106, used as control. The experimental design in both experiments was randomized blocks with two replicates, and evaluated 100 seeds weight, hectoliter weight, yield and nitrogen use efficiency according to the methodology by Fischer et al. (1983) and Moll et al. (1982). The genotypes 12-6; 25-5; 35-5; 12-2; 12-3 and 1-5 formed the group of genotypes of higher yields, independent of soil N, with averages ranging from 6,348 to 5,774 kg ha-1. By the methodology of Moll was possible to differentiate populations for nitrogen use efficiency in environment of low availability of soil N. The characteristics evaluated were influenced by different levels of nitrogen, except for 100 seeds weight. The populations studied differ itself in all characteristics, indicating variability. Moll index was significantly associated with all characteristics studied except for the Fischer index, indicating possible to obtain genotypes efficient in nitrogen use by selection of these characteristics.