Prospects of using cassava as temporary shade for cocoa in degraded areas
There have been significant advances in breeding for cocoa varieties with high yield in Ghana and elsewhere. The best yield so far achieved was in Malaysia, where 6000 kg. ha.-1 year, representing only 16-20% of the yield potential of cocoa was recorded. Recent evidence suggests that yield in cocoa is source-limiting (as only 2% of cherelles pass the wilting stage) and not sink limiting. There appears to be a considerable scope for increasing yield of coca through management practices. Cocoa, in comparison to many perennial crops, has a general requirement for shade. Cocoa, therefore, is traditionally planted under mixed forest shade trees. The forest trees serve as permanent shade and plantain is usually planted as temporary shade (during establishment of new farms). However, plantain succumbs to drought in denuded areas and has proven to be unsuitable for use as temporary shade in marginal areas. It is being contended that the provision of optimal shade could maximise cocoa production. Four cassava varieties (Manihot spp.) were planted as temporary shade tree in September 1995 at three spacing (1.2 m x 0.6 m; x 1.2 m and 1.2 m x 2.4 m) at Akumadan. The level of shade provided by the canopies and the control (plantain shade) were assessed, using two matched EEL Light-master Photometers. The cocoa seedlings were transplanted at 1.2 m x 1.2 m spacing under the cassava shade treatments in May/June 1996. The experimental design was a split-plot with three replications. The results show that the survival rates of cocoa seedlings during the two drought seasons following field transplanting were improved by an average of 14% over the plantain shade with the best performing cassava variety showing 20% and the least 8%, receptively. The growth of cocoa seedlings assessed by height and girth measurements was not affected by the shade treatments. Sixty three percent of the seedlings from the cassava shade plots (compared to 48% in the control) jorquetted by the third year after transplanting, an indication of better establishment.
JOURNAL OF THE GHANA SCIENCE ASSOCIATION Volume 2 No. 3 (2000) pp. 158-163