Resumo

GUEVARA-ESCOBAR, Aurelio et al. Rhodes grass production under a eucalypt canopy. Agrociencia [online]. 2012, vol.46, n.2, pp.175-188. ISSN 2521-9766.

Grass pasture is important for the short term sustainability of agroforestry systems. Growth rate (GR) and pasture dry matter accumulation (DMA) were studied in order to understand competition relationships, by establishing: 1) the decrease as a result of the effect of shade, and 2) the relation with environmental variables, in a eucalypt (Eucalyptus globulus Labill.) block planted at 950 stems h^-1, and associated to a Chloris gayana Kunth pastureland (Rhodes grass), from 2007 to 2009. The eucalypt plantation (EP) was compared with the open field dominated by Rhodes (OF) in Zapopan, Jalisco, México, for one year. The minimum average temperature was higher in the EP than in the OF; soil moisture in the superficial strata and wind speed were lower in the EP; the magnitude of the difference was 4.6 °C, 5 to 8 % v/v and 1 ms^-1. Eucalypt canopy closure was 44 % and it reduced the photosynthetically active radiation (PAR) received in the EP by 75 %, as compared to the OF. The GR was lower in EP than in OF during the rainy season, but in September and December-May, it was similar. The maximum GR for Rhodes was 75 and 48 kg DM ha^-1d^-1 , for OF and EP. The DMA was lower in the EP than in the OF, and the maximum reached was 1.7 and 4.7 Mg DM ha^-1. Soil moisture was a limiting resource for Rhodes in both environments and, in the EP, minimum temperature in second place.

Palavras-chave : Chloris gayana; Eucalyptus globulus; commercial plantations; growth rate.

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