Agronomic performance of interspecific Paspalum hybrids under nitrogen fertilization or mixed with legumes

Abstract

Nitrogen supply and mixtures with legumes affect agronomic performance of pas- tures, and both practices can guide breeding decisions in Paspalum hybrids. The goals of this study were: (a) quantify herbage accumulation (HA), leaf accumulation (LA), cold tolerance, and N use efficiency (NUE) in P. plicatulum × P. guenoarum hybrids subjected to N fertilization or grown in a mixture with legumes; (b) compare the grass–legume system to a grass–N fertilizer system; and (c) select the best hybrid for future cultivar releases. A randomized complete block design with three repli- cations and a split-plot treatment arrangement was used for 2 yr, with five N rates (0, 60, 120, 240, and 480 kg N ha−1) and a grass–legume mixture [grass + white clover (Trifolium repens L.) + birdsfoot trefoil (Lotus corniculatus L.)] as whole plots, and six genotypes as subplots (hybrids: 1020133, 102069, 103084, 103061; and controls: P. guenoarum ‘Azulão’ and Megathyrsus maximus ‘Aruana’). Higher N rates increased HA, LA, and cold tolerance. Higher NUE was obtained between 60 and 120 kg N ha−1. In the grass–legume mixture HA was similar to the rates of 60 and 120 kg N ha−1. Hybrid 1020133 had HA similar to the controls, LA greater than Aruana, and greater cold tolerance and NUE at 60 kg N ha−1 than Azulão and Aruana. Hybrid 1020133 should be selected for further animal performance stud- ies. The agronomic performance of perennial pastures can be improved through N management, and NUE should be a selection criterion in forage breeding.