Seasonal herbage accumulation and canopy characteristics of novel and standard brachiariagrasses under N fertilization and irrigation in southeastern Brazil

Abstract

Understanding seasonal changes in herbage accumulation (HA) and canopy characteristics of tropical grasses aids management of forage–livestock systems and optimizes use of novel cultivars in traditional and integrated systems. The objective of this study was to describe and explain seasonal HA and canopy characteristics of three standard brachiariagrass cultivars in southeastern Brazil under conditions of N fertilization and irrigation: ‘Basilisk’ signalgrass [Brachiaria decumbens (Stapf.); syn. Urochloa decumbens (Stapf) R. D. Webster]; two commercially released palisadegrass [B. brizantha (Hochst. Ex A. Rich.) Stapf.; syn. U. brizantha (Hochst. ex A. Rich.) R. D. Webster] cultivars, Marandu and Xaraés; and unreleased selections of palisadegrass, Arapoty and Capiporã. Grass plots were mechanically harvested every 28 d during the warm season and every 42 d during the cool season to 15-cm stubble starting in September 2005 and ending in September 2008. Capiporã and Xaraés were the most productive (15.6 and 14.6 Mg dry matter [DM] ha−1, respectively) despite having greater seasonality of growth. Arapoty did not show advantages over the cultivars Basilisk and Marandu, with similar total annual HA (∼11 Mg DM ha−1). Arapoty and Basilisk forage averaged 50% more stems than the other grasses in the warm season. Leaf area index (LAI) and light interception (LI) at harvest did not vary among grasses in Year 1, with an average of 3.1 and 90.3%, respectively, and were generally greater for Marandu in Year 2. Capiporã and Xaraés are options for intensive pasture-based livestock production systems and for pasture diversification in tropical areas because of their good HA with great leaf proportion.