Characterization of brazilian wheat cultivars in terms of nitrogen use efficiency

Nitrogen (N) management in wheat crop is one of the most studied agricultural practices in Brazil; however, there are few reports on its use efficiency. The objective of this study was to characterize 18 Brazilian wheat cultivars, which are representative and have been recently released to cultivation, for nitrogen use efficiency (NUE). The experiments were carried out in Pato Branco, Parana, and Coxilha, Rio Grande do Sul, during the 2011 crop season. It was used a randomized block design with three replications, in factorial scheme (2 environments x 18 cultivars). Genetic variability was observed for nitrogen utilization efficiency by grains (NUtEg=47.6 to 81.1 kg kg(-1)) and nitrogen harvest index (NHI=71.3 to 84.6%) with significant effects relating to the environment of cultivation and performance of these traits. The evaluation of the protein concentration of grain by near infrared spectrometry (GPC(N)) produced equivalent results to the direct analytical method of Kjeldahl (GPC(kappa)), in Pato Branco (r=0.56) and Coxilha (RS) (r=0.80). However the CPG(N) overestimated the protein values by 16.85%. The GPC and protein yield were positively correlated with NUtEg and NHI. The best performance for the traits associated with NUE was observed for the following cultivars: Mirante, Quartzo, Fundacep Cristalino, Fundacep Rafzes and CD 150. This is the first report of differences between Brazilian wheat cultivars for nitrogen use efficiency.