Canopy height and N affect herbage accumulation and the relative contribution of leaf categories to photosynthesis of grazed brachiariagrass pastures

Author(s)

Yasuoka, J. I. ^[1] ; Pedreira, C. G. S. ^[1] ; da Silva, V. J. ^[1] ; Alonso, M. P. ^[1] ; da Silva, L. S. ^[1] ; Gomes, F. J. ^[1]

Affiliation

^[1] Univ Sao Paulo ESALQ USP, Coll Agr, Dept Zootecnia Luiz de Queiroz, Piracicaba, SP - Brazil

• Document type: Journal article
• Source: GRASS AND FORAGE SCIENCE; v. 73, n. 1, p. 183-192, MAR 2018.
• Web of Science Citations: 7

Abstract

The effects of three canopy heights (10, 25 and 40cm) and two N rates (50 and 250kgha(-1)year(-1)) on herbage accumulation (HA), participation of leaf categories in the leaf area index (LAI) and photosynthesis of grazed Mulato II brachiariagrass (Brachiaria brizanthaxB.decumbensxB.ruziziensis) were investigated during two summer growing seasons in Piracicaba, SAo Paulo, Brazil. The HA and LAI increased linearly from 8560 to 13600kgDMha(-1)year(-1) and 2.3 to 5.5m(2)m(-2), respectively, as canopy height increased. Mulato II brachiariagrass maintained at 10cm canopy height showed greater proportion of young leaves, but was less productive than taller canopies. Taller canopies had greater proportion of mature leaves in the LAI as well as greater photosynthesis. The greater N rate contributed to increased LAI, leaf and canopy photosynthesis rates and HA but did not affect the LAI composition. The total leaf area is more important to HA than the proportion of young leaves in the LAI, as taller canopies were more productive, suggesting that maintaining Mulato II brachiariagrass at 25 or 40cm is advantageous for this grass. (AU)

• FAPESP's process: 14/16717-4 - Carbon assimilation and herbage accumulation of mulato II brachiariagrass under contrasting growth rates and sward heights maintained by continuous stocking
• Grantee: Júnior Issamu Yasuoka
• Support Opportunities: Scholarships in Brazil - Master