ABSTRACT
Nitrogen use efficiency and forage production in intraspecific hybrids of Paspalum notatum Flüggé

Larissa A. Graminho1*, Miguel Dall’Agnol1, Luciana Pötter2, Carlos Nabinger1, Eder A.M. da Motta1, Cleber H.L. de Souza1, Karine C. Krycki1, Roberto L. Weiler1, Augusto F. Correa1, and Douglas Neto1
 
The rational use of N fertilization is essential to increase the recovery efficiency and crop productivity and decrease the cost of production. The objective of this study was to assess forage yield (TDM), tillers population density (TPD) and N use efficiency (NUE) in six Paspalum notatum Flüggé genotypes in response to N fertilization. The experimental design involved randomized blocks on a subdivided plot design. In 2014-2015 the TDM was higher for the C22 and B26 hybrids (P < 0.0001), which were similar to each other, with an average of 6173 kg DM ha-1 yr-1. In 2015-2016 the TDM of the genotypes ranging from 7053 to 13773 kg DM ha-1 yr-1, for pastures fertilized with 0 and 480 kg N ha-1 yr-1, respectively. An interaction was found between Genotype × N fertilization level (P = 0.0155) for TDM in 2016-2017. In the years 2015-2016 and 2016-2017 the C22 hybrid standed out as the genotype with the highest tiller production in response to N fertilization. In the year 2014-2015 NUE was higher (P = 0.0015) in the N fertilization levels N60, being of 15.5 kg DM kg-1 N. In the years 2015-2016 and 2016-2017 the NUE was higher at fertilization level N120 (P < 0.05), being of 21.1 and 31.5 kg DM kg-1 N, respectively. The C22 hybrid was distinct as the genotype with the highest DM yield and superior tillering characteristics. The N fertilization level of 120 kg N ha-1 yr-1 promoted greater NUE in all P. notatum genotypes.
Keywords: Apomixis, genetic improvement, hybridization, tillering.
1Universidade Federal do Rio Grande do Sul, Faculdade de Agrônomia, Avenida Bento Gonçalves, 7712, CEP 91540-000, Porto Alegre, Rio Grande do Sul, Brasil. *Corresponding author (laraarnhold@hotmail.com).
2Universidade Federal de Santa Maria, Avenida Roraima, 1000, CEP 97105-900, Santa Maria, Rio Grande do Sul, Brasil.