Carbon Assimilation, Herbage Plant-Part Accumulation, and Organic Reserves of Grazed 'Mulato II' Brachiariagrass Pastures

Author(s)

Silva, Valdson J. ; Pedreira, Carlos G. S. ; Sollenberger, Lynn E. ; Silva, Liliane S. ; Yasuoka, Junior I. ; Almeida, Iane C. L.

• Document type: Journal article
• Source: CROP SCIENCE; v. 56, n. 5, p. 8-pg., 2016-09-01.

Abstract

Pasture management, including the control of grazing intensity and fertilization, can trigger plant physiological and morphological responses that affect plant growth and impact stand persistence. The objective of this research was to quantify the effects of three canopy heights (10, 25, and 40 cm), maintained by mimicking continuous stocking, and two N rates (50 and 250 kg ha(-1) yr(-1)) on canopy carbon exchange rate (CER), plant-part accumulation, and organic reserves of 'Mulato II' brachiariagrass hybrid (Brachiaria brizantha x B. decumbens x B. ruziziensis), also known as Convert HD 364 (Dow AgroSciences, Sao Paulo, Brazil) during two summer rainy seasons in Piracicaba, Brazil. Leaf CER was greater for the 10-cm height, but canopy CER, plant-part accumulation, root mass, and root reserves were less in 10-than 40-cm canopies, although this was not associated with stand deterioration after 2 yr. Leaf was the predominant plant part, and leaf accumulation rate increased linearly from 70 to 100 kg dry matter (DM) ha(-1) d(-1) as canopy height increased from 10 to 40 cm. Increasing N rate from 50 to 250 kg N ha(-1) yr(-1) affected plant growth, increasing CER, leaf area index, and the rates of leaf, stem, and dead herbage accumulation. The senescence-to-growth ratio (S:G) was not affected by N rate, indicating that the increase in rate of dead material accumulation with greater N rate was a result of an increase in the accumulation rates of all plant parts. Taller canopy heights (25 or 40 cm) are recommended for Mulato II under continuous stocking. (AU)

• FAPESP's process: 13/01777-9 - Modeling carbon assimilation and morphogenesis responses of Mulato II Brachiariagrass under contrasting growth rates and in response to canopy height maintained by continuous stocking
• Grantee: Valdson José da Silva
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 14/08789-5 - Herbage accumulation, grazing efficiency, morphogenetic characteristics and modeling carbon assimilation of Mulato II brachiariagrass under contrasting growth rates and in response to canopy height maintained by continuous stocking
• Grantee: Valdson José da Silva
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate