PF 15. Shade tolerance of herbaceus forage species in humid tropic of Costa Rica

The objective of this study was to determine the effect of different light levels on DM production and physiological responses of four forage species Brachiaria brizantha (Bb), Panicum maximum (Pm), Arachis pintoi (Ap) y Axonopus compressus (Ac) stablished in a split plot design with three replications at “Los Diamantes” Experimental Station. Mean rainfall of the region is 4 332 mm/year and daily temperature 24.2 °C, soils were medium to high fertility. Sarloin cloth was used to simulate the light levels (main plots): 25, 50, 70 % and 100 % of total light. The plots were established in September 1994 and the experiment was started in January, 1995 with uniformisation of all plots (5 cm for prostrate species and 20 cm for erect species). Measurements were taken on leaf area index DM yield and radiation use efficiency. From the results, it was concluded that Pm and Bb maintained high DM production under moderate light levels which should be considered for the establishment of silvopstoral systems. In addition, the legume Ap showed excellent plasticity for shade tolerance and this together with high quality sustained under shaded conditions are good attributes for its integration in plantation grazing systems