The effects of shade and dry season irrigation was examined on cacao water use, canopy properties, radiation integrals, pod and bean yields and branch/twig die back of cacao. The study will be relevant to intensification of agriculture and improved water productivity in the frame of climate change. The experiment was 2 by 2 factorial combinations of irrigation intervals (5 and 10 days) with shade and unshaded laid out in split-plot scheme and three replications. The irrigation and shading regimes affected solar radiation properties, photosynthetic active radiation (PAR), light attenuation (extinction coefficient, k) and leaf area index (LAI) of cacao. The unshaded-irrigation combinations had higher PAR intensity, LAI and canopy extinction (k) compared with shaded-irrigation. Differences were found for seasonal irrigation (30902.2 and 21813.3 mm), soil moisture contents (18.7 and 17.4: 15.1 and 13.8 %), cacao water use (ETc: 3.8:3.6 and 3.4: 3.2 mm/day) for shaded and unshaded plus 5- and 10-day irrigation. Unshaded-irrigation combinations out-yielded shaded-irrigation for flowers, pod (78000 to 6000 kg/plant) and bean (16-10 & 130-110 g) yields and water productivities (irrigation WUE: 0.45 to 0.33 mm/kg/ha and WUE ETc: 0.11 to 0.09 mm/kg/ha). Pod and bean yields were significantly higher under 5-day irrigation compared with the 10-day interval. The shade-irrigation combinations can be scaled up for adoption for the enhancement of establishment, pod and bean yields of cacao.
Keywords: Cacao, shade, LAI, light extinction, radiation, wet-dry transition, die-back, climate stress, tropics