Light relations and performance of signal grass in silvopastoral system/Relacoes luminosas e desempenho do capim-braquiaria em sistema silvipastoril

• Published in: Acta scientiarum. Animal sciences 2014-04, Vol.36 (2), p.129
• Main Authors: Rodrigues, Cynara Oliveira Diniz, Araujo, Saulo Alberto do Carmo, Viana, Maria Celuta Machado, Rocha, Norberto Silva, Braz, Thiago Gomes dos Santos, Villela, Severino Delmar Junqueira
• Format: Article
• Language: Spanish
• Subjects: Photosynthesis; Radiation
• ISSN: 1806-2636
• DOI: 10.4025/actascianimsci.v36i2.22398

The aim was to evaluate the influence of different spatial arrangements of trees [(3x2)x20 m, (2x2)x9 m and 2x9 m] and sampling sites (center of row spacing and side of tree rows) with regard to the amount and quality of light in the understory of silvopastoral systems and their effects on the production and chemical composition of pasture. The experimental design was a randomized block in a split plot, with three replications. The sampling site affected absolute irradiance, photosynthetic active radiation (PAR), light interception (LI) and red/far red ratio, with higher rates in the center of spacing. There were high and positive correlations between LLleaf area index (LAI), LLdry mater (DM) and LALDM in the center and LI/LAI and FAR/DM in the side of tree rows. Spatial arrangement (3x2)x20 m had higher rates for plant height (PH), DM and neutral detergent fiber rate, while (2x2)x9 m had high leaf/stem ratio and crude protein rate. In the case of the sampling site, higher rates of PH and DM were reported in the center. Forage composition was not affected by sampling sites. Highest production of DM was obtained in the (3x2)x20 m arrangement and improvements in forage composition were observed in denser arrangements. Keywords: quality of light, shading, spatial arrangements, Urochloa decumbens. Objetivou-se avaliar a influencia de diferentes arranjos espaciais de arvores ((3x2)x20 m, (2x2)x9 m e 9x2 m) e locais de amostragem (centro e lateral da entrelinha) na quantidade e qualidade de luz no sub-bosque de sistemas silvipastoris e seus efeitos na producao e composicao bromatologica da pastagem. O delineamento utilizado foi blocos casualizados em parcelas subdivididas, com tres repeticoes. O local de amostragem influenciou a irradiancia absoluta, a radiacao fotossinteticamente ativa incidente (RFAi), interceptacao luminosa (IL) e relacao vermelho/vermelho distante, sendo determinados maiores valores no centro das entrelinhas. Observou-se correlacoes altas e positivas entre IL/indice de area foliar (IAF), IL/producao de massa seca (PMS) e IAF/PMS no centro e IL/IAF e RFAi/PMS na lateral das entrelinhas. O arranjos espaciais (3x2)x20 m apresentaram maiores valores para altura da planta (AP), PMS e teor de fibra em detergente neutro, enquanto o (2x2)x9 m apresentou maiores valores para relacao folhaxolmo e teor de proteina bruta. Quanto ao local de amostragem, os maiores valores de AP e PMS foram observados no centro. A composicao da forragem nao foi influencia