Abstract
ABSTRACT: This study examined the effects of annual nitrogen (N) rates of 100 and 200 kg ha-1 on the morphogenetic and structural traits of Ipyporã grass (Brachiaria brizantha × Brachiaria ruziziensis) under intermittent grazing during the seasons of the year. The experiment was laid out in a randomized-block design with two treatments and three area replicates. Ipyporã grass pastures were grazed by beef cattle. Morphogenetic and structural traits of the forage canopy were evaluated using the marked-tiller technique. Forage accumulation and tiller density (TD) were also evaluated. Significant interaction effects (P < 0.05) between N rates and seasons were observed for the rest period, leaf lifespan (LLS), phyllochron, stem elongation rate (SER) and final leaf length (FLL). During winter, the rest period was shorter (40 vs. 50 days) in the pastures fertilized with 200 kg ha-1 N. Conversely, in winter, the pastures fertilized with 100 kg ha-1 N showed higher LLS, SER and phyllochron values, but lower FLL values. There was no isolated effect of N rates (P > 0.05) on forage accumulation rate; leaf appearance, elongation or senescence rates; leaf:stem ratio; or TD. However, the effect of seasons was significant for these variables, with the highest values occurring during spring and summer. The use of 200 kg ha-1 N in Ipyporã grass pastures reduces the seasonality of forage production.
Highlights
Ipyporã grass is an interspecific Brachiaria hybrid (B. brizantha × B. ruziziensis) with antibiosis resistance to the froghopper (Notozulia entreriana, Deois flavopicta, Mahanarva fimbriolata and Mahanarva sp.) (VALLE et al, 2017)
The present study examined the effects of annual N rates of 100 and 200 kg ha-1 on the morphogenetic and structural traits of Ipyporã grass under intermittent grazing during the seasons of the year
Light interception averaged 92.25 ± 0.42%, which is within the predefined target of 9095%
Summary
Ipyporã grass is an interspecific Brachiaria hybrid (B. brizantha × B. ruziziensis) with antibiosis resistance to the froghopper (Notozulia entreriana, Deois flavopicta, Mahanarva fimbriolata and Mahanarva sp.) (VALLE et al, 2017). The present study examined the effects of annual N rates of 100 and 200 kg ha-1 on the morphogenetic and structural traits of Ipyporã grass under intermittent grazing during the seasons of the year.
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