Shade and Irrigation Effects on Growth, Flowering, Pod Yields and Cacao Tree Survival Following 5 Years of Continuous Dry Season Irrigation

Abstract

The effects of plantain shade and dry season irrigation on the growth, field survival, flowering and pod production of cacao was investigated. Treatments were a 2 by 2 factorial combinations of shade regimes (Unshaded/open sun and shaded) and irrigation intervals (5-day and 10-day intervals) arranged in a split-plot design. There was an unirrigated but shaded control. The shade regimes constituted the main plot while irrigation intervals were the sub-plot treatments. The growth, dry season survival, flowering and pod/bean yield characters of cacao were enhanced in the unshaded (open sun) compared with the shaded plants. The open sun treatment combined with 5-day irrigation produced the largest canopy development, flowering and pod production compared with shading-irrigation combinations. The shade-irrigation ameliorated microclimate and enhanced growth and development, flowering and uniform fruiting/pod production and total bean yield and reduced dry season mortality (whole tree death, branch and twig dieback). For the non-irrigated but shaded cacao, about 30% dry season mortality (branch and twig dieback) were obtained. Air temperatures within the cacao field were highest for open sun cacao followed by moderate and dense shade respectively. Flowers were more profuse for unshaded (open sun) cocoa compared with the shaded while the yield and yield components of cacao for each harvest dates and total pod and bean yields were significantly different between the unshaded and shaded cacao regimes. Trees that were irrigated at 5-day intervals produced significantly (P < 0.05) higher LAI, branching, flowers and pods compared with those irrigated at 10-day intervals. The 5-day irrigation interval significantly increased percentage of trees bearing flowers and pods, and produced larger number, and heavier pods and beans compared with the 10-day interval. The drip irrigation strategy adopted ameliorated dry season terminal drought (hydrothermal stresses) in cacao. This is a veritable tool to scale up growth, survival, establishment and flower/pod production.