Evaluation of photosynthetic variables of Brachiaria brizantha under eucalyptus canopies in a livestock-forestry integration system
¹Federal Fluminense University, Department of Agricultural Engineering and Environment, Street Passo da Pátria, n.156, São Domingos, Zip Code: 24210-240, Niterói- RJ, Brazil
²Brazilian Agricultural Research Corporation, Soils Research Unit, Zip Code: 22460-000, Rio de Janeiro-RJ, Brazil
³Brazilian Agricultural Research Corporation, Agrobiology Research Unit, Zip Code: 23891-000, Seropédica-RJ, Brazil
⁴Brazilian Agricultural Research Corporation, Dairy Cattle Research Unit, Zip Code: 36038-330, Juiz de Fora-MG, Brazil
⁵Federal Rural University of Rio de Janeiro, Soils Department, Zip Code: 23890-000, Seropédica-RJ, Brazil
*Correspondence: jroliveira@id.uff.br
Abstract:
Livestock sector generates significant environmental impacts despite its global economic importance. The current challenge is to find sustainable ways of boosting this sector, while mitigating the negative impacts of this activity. In Brazil, degraded pastures are common because of inadequate management, damaging the soil. Integrated livestock-forestry (ILF) systems combine forest species and pastures in the area, incorporating elements of sustainability. In this system, the tree species is related to the productivity of the pasture, as the shade generated by the canopy creates different light conditions, influencing the photosynthetic activity of the forage. The aim of this study was to evaluate the influence of the luminosity of the understory of an ILF system on the photosynthetic activity of the forage species Brachiaria brizantha in the Atlantic Forest region of Brazil. Transient chlorophyll a fluorescence and chlorophyll concentration were analysed in forage plants grown in consortium with Eucalyptus urograndis (Clone 1407), with spacing of 4m between trees and 24m between tree rows. Two treatments were established based on light conditions: the control treatment, corresponding to the condition with the highest light corresponded to the pasture row, and the treatment with the lowest light, corresponding to the area under the canopy. The results show that the low light supplied to the forage plant, during the experiment period, under eucalyptus canopies, promotes changes in the intensity of chlorophyll a fluorescence and chlorophyll concentration, indicating low efficiency of the electron transport chain and changes in leaf nitrogen content, due to a possible stress situation.
Key words:
cattle, forage, light stress, photosynthesis, silvopastoral system