Comportamiento ecofisiológico de Brachiaria decumbens en monocultivo y en asociación con Leucaena leucocephala.

In order to study the ecophysiological relations that affect the growth of B. decumbens in monocrop (MO) and associated withZ. leucocephala (AS), evaluations of photosynthetic active radiation (PAR), assimilation (A) stomatic conductance (Gs), transpiration (E), relative humidity (RH), water potential (0h), differential of steam pressure (DSP) and leaf area index (LAI) were made in a tropical humid forest zone. The evaluations were made 5,10 and 22 days after grazing under both conditions (MO and AS). The most positive values of 0h (P<0,05) were found in AS, as well as the lowest values of PAR (P<0,05) in all the evaluated dates. RH and DSP did not show differences (P 0,05). The gas exchange parameters (E, Gs and A) showed significantly higher values in MO (P<0,05) in all dates. LAI was higher in MO after 10 and 22 days of evaluation. Due to the limitation of the photosynthetic capacity exerted by the light decrease on the grass, that PAR is concluded to be the most important factor that determine growth and development of B. decumbens in AS. [ABSTRACT FROM AUTHOR]