Nitrogen Use Efficiency and Biomass Yield in Paspalum Interspecific Hybrids in Response to Nitrogen Fertilization.

The genetic improvement of Paspalum spp. through hybridization has made available novel genetic resources for livestock production; however, it is unknown the fertility requirements on the productive potential of these new hybrids. The goal of this study was to evaluate biomass yield and nitrogen use efficiency (NUE) in hybrids of Paspalum plicatulum x P. guenoarum in response to different levels of nitrogen (N) fertilization. Treatments consisted of a factorial arrangement of 6 genotypes [4 hybrids: 10E20133, 10E2069, 10E3084, 10E3061, P. guenoarum ecotype “Azulão” and Megathyrsus maximus (Jacq.) cv. “Aruana” used as a control] and 5 levels of N (0, 60, 120, 240 and 480 kg ha^-1), under a randomized complete block design with three replicates. NUE was calculated according to the following equation NUE = (yield fertilized plot – yield unfertilized plot)/ (applied nitrogen level). Dry-matter yield (DMY) and NUE were affected by levels of N fertilization. DMY of the hybrids 10E20133, 10E2069, 10E3084 and 10E3061 and ecotype “Azulão” showed quadratic response for the N levels. “Aruana” showed a linear response. DMY ranged from 10,167 to 23,238 kg DM ha^-1 when N levels increased from 0 to 480 kg N ha^-1. A decrease in NUE was observed when N levels increased from 60 to 480 kg N ha^-1. When applied at the 120 kg N ha^-1, NUE was similar to the 60 and 240 kg N ha^-1 levels. Interspecific Paspalum hybrids respond to N fertilization and the amount N applied should be based in highest NUE.

Keywords: forage, hybrids, nitrogen, Paspalum