The Bananas of Upland East Africa - PRINCIPAL ELEMENTS OF THE 1987-1990 RESEARCH PROGRAMME, continued |
In their report, WALKER et al (op cit, 1983) briefly discussed the question of experimental design and identified the possible need for a move away from the extremely large, and consequently expensive, randomized block technique in field trials. The paired stool method was suggested but simply in the context of a untreated versus treated pair of stools.
To me, there seemed no fundamental reason for the use of randomized blocks in banana field trials. The technique had been developed over many years for use in cereal crops, where each individual plant has a very small yield and occupies a minute area of land. Large numbers of plants and plots big enough to avoid edge effects, and the like, became the norm. In contrast, in medical and veterinary research, for instance, large numbers of experimental individuals normally are not available and the use of individuals or pairs as replicates is usual. In tree crop studies a similar system has been evaluated but, in my experience of the present author, observations on the microenvironment of the individual trees have not always been sufficiently detailed.
At Maruku Agricultural Research Institute, there was a collection of over 200 named "varieties" (MBWANA op cit, 1987). How many genuinely distinct clones were are represented was not clear and much more needed to be done to synonymize the collection. In the collection may ahve lain some of the means of combatting the problems faced by farmers in the region and, after synonymization, evaluation of agronomic characteristics of the clones and their response to field stresses was an urgent requirement.
Traditionally in Kagera, the banana shamba is regarded as a perennial crop with almost no intention on the part of the farmer of replanting other than, for instance, the filling in of holes left by stool death. In recent years, at least, replanting to re-establish debilitated shambas had become quite common but this had been immediate with no break period. Where nematode attack was the cause of the debilitation, deterioration of the newly planted bananas had set in rapidly. Further immediate replanting often followed but with equal lack of success. A break period almost certainly is required but the duration of the gap between banana uprooting and replanting needed to be established. The loss of the staple food necessitated the planting of an alternative crop and the question of which crops or other plants might act as alternative hosts for the nematodes also needed to be investigated.
No work on this had been done either in Kagera or, apart from the attempted introduction of Plaesius javanus in Uganda, elsewhere in East Africa. A possibility raised by WALKER et al (op cit, 1983) was for a fresh search for Cosmopolites sordidus predators or parasites in the area of origin of bananas and, subsequently, investigation of the potential for release of any such biological control agents.
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| ©2000 - Brian Taylor CBiol FIBiol
FRES 11, Grazingfield, Wilford, Nottingham, NG11 7FN, U.K. Visiting Academic in the Department of Life Science, University of Nottingham |
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