Avaliação e divergência genética de linhagens parcialmente endogâmica para eficiência no uso de nitrogênio em milho

Abstract

Maize is one of the most demanding fertilizers culture, especially nitrogen. The genetic breeding can contribute to reduce the use of nitrogen fertilizer obtaining cultivars that are efficient in the nitrogen use.The objective of this work was select partially inbred maize lines with efficient of nitrogen use. It have been used 42 maize lines S3 previously selected based on efficiency studies for the nitrogen use and seven commercial hybrids as control. Three simultaneous experiments were carry out in Dourados, Glória de Dourados and Laguna Carapã; all in Mato Grosso do Sul state. The experimental design was incomplete blocks in simple lattice 7x7. The experimental plot consisted of a line of 5 m, spaced 0.90 m between rows and 0.20 m between plants. It was applied 30 kg ha-1 and 120 kg ha-1 N to characterize the environment with and without nitrogen stress, respectively. The inbred maize lines presented genetic variability for seed yield in low nitrogen availability,therefore, there is the possibility of selecting partially inbred lines to produce hybrids efficient in nitrogen use. The lines L3, L6, L7, L9, L10, L12, L13, L14, L16, L23, L26, L28, L31, L32, L34, L35, L37, L38 and L39 presented potential to be exploited as a source of germplasm to obtain cultivars tolerant in low nitrogen availability aiming cultivation by small producers. The use of the three clustering techniques allowed the individualization of the lines L5, L36, L9, L6 and L41, that even changing the grouping method these genotypes had the highest dissimilarity.