Herbage accumulation, canopy structure and tiller morphology of marandu palisadegrass growing in open pasture and in silvopasture

Abstract

Silvopasture is an alternative to open pasture (OP), but the effect of trees on understory grass canopy structure and tiller morphology is not well defined. Our objective was to compare herbage accumulation, canopy structure, and tiller morphology of Brachiaria brizantha (Hochst. ex A. Rich.) Stapf. cv. Marandu (palisadegrass) growing in OP or in silvopasture with Eucalyptus urograndis (hybrid of E. grandis W. Hill ex Maiden and E. urophylla S. T. Blake), in the Amazon biome. From October 2015 to September 2016, all experimental units were stocked continuously with beef cattle using a variable stocking rate to maintain a palisadegrass canopy height of 30 cm. The trees were planted in triple-row groves (3.0 m between trees, 3.5 m between rows), with 30 m between groves, totaling 270 trees ha−1. The herbage accumulation (HA) was similar among systems (averaging 12.1 Mg ha−1 year−1). The silvopasture decreased herbage mass (HM) 24% and herbage bulk density (HBD) by 20% compared with OP. Tiller leaf area was 18% greater in the silvopasture. Total number of leaves (4.95 ± 0.26), and live leaves tiller−1 (3.25 ± 0.14) were not affected by system or system × season interaction. In a silvopasture, palisadegrass maintained leaf area index, number of total, live and dead leaves, tiller weight, internode length and stem length similar to the OP. Under moderate shade, especially at 4-m distance from the edge row of trees, palisadegrass enhanced the area of each leaf while the number of live leaves tiller−1 and tiller density decreased in order to maintain productivity. Silvopasture has potential as an alternative system for livestock production in the Brazilian Amazon Biome.