Preliminary selection of avocado pear (Persea americana Mill) types for the fresh fruit market from the Atwea and Ninting areas of the Ashanti region of Ghana

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The bulk of avocado pear (Persea americana) fruit found on the Ghanaian market come from volunteer trees. Though the fruit is exotic there is little or no records about its introductions into the country. The use of the seed in propagation has resulted in a great diversity in the tree and fruit characteristics. Though the fruit has a high demand both locally and on the export market, large scale monocrop of the fruit is virtually non-existent due to the absence of selected trees that are proven to be of high quality and adapted to the Ghanaian climatic, soil and other edaphic conditions. The introduction of known and proven varieties into the country would not adequately and satisfactorily solve the problems of variations in growth habits and quality. It is therefore necessary to select from local varieties which have adapted to the local conditions for further development Eight out of twenty-five marked bearing avocado pear trees in the Atwea and Ninting areas of the Ashanti region were chosen for data collection and fruit analysis. Data on time of flowering, fruit set, fruit development, maturity and harvesting were collected for both the major and minor seasons. Fruit weight, shape, colour, peel thickness, meat weight, presence or absence of fibres and creaminess were determined. Seed weight, shape, its looseness or tightness in the fruit, meat-seed ratio, and percent oil content, dry matter and shelf life were also determined. Flowering and fruiting on the marked trees were generally earlier at Ninting than at Atwea for both the major and minor seasons. Significant differences in fruit, meat and seed weights occurred among the marked eight experimental trees. Al0 recorded the largest fruit weight with a mean of 506g while A8 recorded the smallest fruit weight with a mean of 194.6g. Fruits from the tree labelled AS were medium in size with a mean fruit weight of 359g, and a meat weight of 231g. Al0 again recorded the highest meat weight with a mean of 359.9g while A9 recorded the highest seed weight with a mean of 104.3g. In terms of seed weight as a percentage of the freshly harvested fruit N2 recorded the highest (27.5%) while those of AS and Al0 were 17% and 15.1% respectively with that of A 10 being the lowest. When meat weight was calculated as a percentage of the freshly harvested fruits Al 0 had the highest percentage of 71.1 that of A5 was 64.3% while N2 recorded the lowest percentage of 54.2. There was an inverse relation between meat weight and seed weight. The meat-seed ratio was highest for Al0 and lowest for N2. The most uniform fruits were obtained from N14 while the least uniform ones were from A9. Generally, smaller sized fruits lost more weight at ripening than larger fruits with the exception of N1. Fruits from A5 were pear shaped, green in colour when ripe and had thick buttery meat with tight seeds. From the results AS was recommended for selection and further development for the export market while N1, A9 and Al 0 were recommended for selection and further development for the local market.
A thesis submitted to the Board of Postgraduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirements for the award of the Degree of Master of Science, 1995