Physiological characteristics and forage accumulation of grazed Marandu palisade grass (Brachiaria brizantha) growing in monoculture and in silvopasture with Eucalyptus urograndis

Abstract

Adoption of silvopasture is increasing, but proper design and management of pasture–tree associations is required to sustain pasture productivity. Our objective was to compare agronomic and physiological characteristics of Brachiaria brizantha (Hochst. Ex A.Rich.) Stapf. (palisade grass) cv. Marandu growing in monoculture, or in silvopasture with Eucalyptus urograndis, in the Brazilian Amazon biome. Trees were planted in triple rows (intra-row spacing 3 m, inter-row spacing 3.5 m), referred to as a grove, with three groves per 2-ha silvopasture experimental unit. Space between groves was 30 m, and tree density was 270 ha–1. From October 2015 to September 2016, all experimental units were stocked continuously with cattle by using a variable stocking rate to maintain a Marandu canopy height of 30 cm. In the silvopasture, sampling occurred at 4, 7.5 and 15 m into the non-treed area from the outer tree row in a grove. Photosynthetically active radiation (PAR) reaching the Marandu canopy averaged 21% less for silvopasture than for grass monoculture; however, forage accumulation was not different between systems, nor were Marandu stomatal conductance, water-use efficiency (WUE), transpiration rate, transpiration ratio and leaf temperature. In silvopasture, PAR and forage accumulation were 33% and 29% less, respectively, at the 4-m distance than the 15-m distance from the edge row of trees, associated with lower transpiration rate and transpiration rate and greater WUE. We conclude that Marandu palisade grass can tolerate PAR reduction in silvopasture up to ~20% without reduction in forage accumulation, supporting its potential use in agroforestry systems for cattle production in the Brazilian Amazon Biome.

Morphogenetic, physiological, and productive of forage peanut responses to shading

“…Leaf temperature is closely associated with leaveswater loss (Monteiro et al, 2016). In the present study, despite the increase of stomatal conductance and transpiration rate, the shading probably decreased the evapotranspiration of the system (Nascimento et al, 2019), affecting the leaf boundary layer resistance, hindering the water loss and heat dissipation and, consequently, increasing the leaf temperature.…”

“…Shading intensity up to 45% favored an increase of the stomatal conductance and transpiration rate, probably due to improvements of the environmental conditions, mainly soil moisture (Monteiro et al, 2016;Nascimento et al, 2019), although this condition was not evaluated in the present study. This response pattern increased the internal CO 2 concentration which, when associated with increased chlorophyll b indices, results in high-photosynthesis rate.…”

Forage and animal production on palisadegrass pastures growing in monoculture or as a component of integrated crop–livestock–forestry systems

“…The lesser HM in the LF system was likewise associated with the least overall HBD. Because HBD is affected by the leaf:stem ratio and tiller density (Pedreira, Pedreira, & Silva, ; Sbrissia & da Silva, ), both of which are affected by light environment, the attenuation of photosynthetically active radiation (PAR) reaching the grass canopy in silvopastoral systems may have reduced HBD (do Nascimento et al, ; Crestani et al, ; Geremia et al, ).…”

Shading Effects on Marandu Palisadegrass in a Silvopastoral System: Plant Morphological and Physiological Responses

“…In the current study soil moisture may have also played a role in supporting Marandu palisadegrass herbage accumulation in the SPS. In the same experimental area, Nascimento et al (2019) reported similar soil moisture (0–20 cm) in the SPS to the grass monoculture system. Overall, more shaded pastures tend to enhance soil moisture due to less evapotranspiration.…”

“…According to Nascimento et al (2019), Marandu palisadegrass HA was not reduced in a SPS with up to 20% reduction in PAR reaching the grass component. The authors also reported that some morphological modifications occurred at the 3-m distance, where the PAR was reduced by about 40%.…”