The author of this chapter is J.A. Morera (Genetic Resources Unit, CATIE/GTZ, Turrialba, Costa Rica).
Common names. English. sapote, mammee zapote, marmalade plum; Spanish: zapote, mamey zapoteo, mamey colorado, zapota grande: French grosse sapote
The sapote (Pouteria sapota), which originates from the lower parts of Central America, is a fruit-tree with tree pollination, which generally multiplies by seed. Its fruit may be eaten raw or green and the flesh is used to make jams, icecreams and sauces; when cooked, it can be an acceptable substitute for apple puree and may also be used in confectionery.
Chemical analysis shows that 100 g of sapote flesh contains 65.6 percent water, 1.7 g of protein. 0.4 g of fat, 31.1 g of carbohydrates, 2 g of fibre, 1.2 g of ash, 40 mg of calcium, 28 mg of phosphorus, 1 mg of iron, 115 mg of vitamin A, 0.01 mg of thiamine. 0.02 mg of riboflavin, 2 mg of niacin and 22 mg of ascorbic acid.
Cultivation of this species still cannot meet the demand of the external market and may play an important role as a source of revenue and in helping to make up an adequate diet, particularly for low-income urban and rural populations.
In some parts of Mesoamerica, ground sapote seeds are used to give chocolate a bitter flavour and characteristic aroma; in Costa Rica, they have been used as a linen starch. In Guatemala and El Salvador, the oil from the seed is used as a skin tonic, to prevent baldness, to reduce muscular pain and to treat rheumatic ailments.
This tree produces latex, which is used as a caustic to remove fungus from skin. Sapote wood, which is strong and solid, can be used to make furniture and other objects that require stout wood.
From the ecological point of view, promoting the cultivation of this species is of enormous importance since it can help maintain genetic diversity and prevent some genotypes of potential value from disappearing. The establishment of this species as a crop in traditional production systems will make it possible to maintain highly sustainable fruit-growing development. Agroindustrial development will benefit from the production of fruit of great nutritional value and by-products of high value added.
The sapote tree can attain a height of 20 to 25 m; its crown is generally symmetrical or irregular, with thick branches and dense foliage. The leaves are ovate or lanceolate and are concentrated on the apex of the branches. The flowers are small, almost sessile, and grow in profusion under new branches and along leafless branches. Each flower consists of five true and five false stamens; the pistil has only one stigma and the ovary has five carpers.
The fruit ranges in shape from fusiform, elongated, ellipsoid to spherical, and may weigh up to 3 kg in some genotypes. The skin is hard, rough and brittle, and is of a dull, reddish colour. The flesh varies in texture and is red, orange or greyish in colour; it is aromatic, sweet and soft when ripe; and usually has some fibres, depending on the cultivar. In general, the fruit contains one or more seeds. These are large with sharp ends and ellipsoid in shape, dark brown in colour. smooth and shiny on the dorsal segment and cinnamon-coloured on the ventral part. The seeds take between 40 and 70 days to germinate, a process that can be speeded up by simply removing or scarifying the husk before sowing.
Figure 9. Sapote (Pouteria sapota): details of a cross section and shapes of the fruit
Very little has been written on the climatic conditions. pests, diseases and other factors limiting the production and productivity of the sapote. However, the most important factors from an ecological point of view are height, soil, temperature and rainfall, since they can limit the cultivation area, and to a great extent, may be considered the most critical factors for its development. In some places, wind may be the most important limiting factor. The ease with which some diseases and insects can spread depends on relative humidity.
The sapote adapts well from sea level up to 1400 m. It grows in the heavy clays of Puerto Rico, the sandy clays of Guatemala and even in the sandy soils of Florida in the United States.
The essential characteristics of the soil for optimum cultivation are the quality of drainage, depth. degree of acidity, fertility, adequate groundwater level and moderate permeability. In tropical areas, there are many soils with these characteristics. However, soil factors are inseparably linked to the sapote plant's photosynthetic potential, for which reason the low fertility of some tropical soils limits the yield of this species.
The sapote does not tolerate low temperatures, even if of short duration. Depending on its locality, the sapote can be profitable if sown in areas where the temperature does not fall below 1 5°C. Extreme temperatures can temporarily affect some of the functions of any of the tree's organs. In regions where the sapote grows best, the average temperature ranges between 25 and 28°C. On some commercial plantations, such as in Leon in Nicaragua, good yields and fruit quality are obtained at temperatures between 30 and 33°C.
The amount of rainfall needed for growing the sapote ranges between 800 and 2500 mm; how much rainfall there is will depend on the type of growing area.
If the dry season is prolonged in a given area, harvesting may be concentrated in short periods while, in places where there is no dry season, the crop can be harvested with maximum fruiting throughout the year.
The word "sapote" (or "zapote") comes from the Aztec "tzapotl", a collective name which applies to several species of sweet, spherical fruits with large seeds. The Sapotaceae family includes other close species of great value, such as the sapodilla (Manilkara zapota), star apple or caimito (Chrysophyllum cainito), canister (Pouteria campechiana), pan de vida (P. hypoglauca), lúcumo (P. obovata) and caimo (P. caimito).
In the most recent taxonomic classification, sapotes comprise three species: Pouteria sapota, P. viridis and P. fossicola, although it is accepted that there are intermediate groups between the three (Pennington, 1990). Despite morphological differences and sometimes differences in geographical distribution, if compared with other fruit-tree species, the value of these three taxa would be at variety level.
In Florida, several cultivars of the sapote are currently grown, of which brief descriptions have been made (Campbell and Lara, 1982). Table 4 indicates the 16 best cultivars.
Table 4 Characteristics of the best sapote cultivars in Florida, 1991
|Cultivar||Harvest||Weight (g)||Flesh colour||Flavour||Yield|
|Area No. 3||July-September||400740||Pink||Good||Regular|
Much of the genetic variability of the genus Pouteria is found in the tropical forest areas which are still unexplored. These regions are not very accessible and, in some cases, guerilla groups in the mountains make it difficult to collect genotypes which may be undergoing genetic erosion through abandonment. Furthermore, urban development is accelerating the loss of genetic diversity of this and other species. It is surprising to note how trees of great value are being felled daily to make way for buildings and other constructions on the best soils with a high agricultural potential.
The Indians, on the other hand, leave sapote trees when clearing the forest and. in Guatemala. they are frequently found on land which has long since been given over to maize.
The protection of genetic resources, including the Sapotaceae family, is an international responsibility. The costs and benefits of this protection should be shared out equitably. In general, many of the countries with a great genetic diversity are developing countries, hence they are unable to defray the costs of in situ protection of genetic resources on their own. An international mechanism is therefore needed to meet the costs this responsibility entails. Such financial support should be used in particular for taking care of populations of endemic species in each ecological region and in zones of exceptional diversity, particularly the lowland forests, tropical and subtropical rain forests as well as isolated mountains and other places where wild species with a high genetic value still exist.
The intensification of agriculture has caused a reduction in the genetic variability of this tropical species by replacing wild cultivars of sapote with other exotic species.
In general, Sapotaceae have been propagated by seed. There are few commercial plantations. Fruit for everyday consumption comes from solitary trees which grow close to people's homes or are interspersed with other perennial crops such as cocoa and coffee.
Until a few years ago this species took seven to eight years to come into production, since sexual propagation by seed was used. This created a wide variation in populations, greatly reducing the possibility of harvesting genotypes that were uniform in size, weight and quality.
At present, the vegetative methods of propagating sapote involve grafting, a system which improves productivity characteristics and halves the period between sowing and harvesting. In this way, incompatibility problems between stock and graft are corrected and the desirable characteristics of grafting are combined with the special qualities of the stock.
Before grafting, there must be a good selection of stocks. Grafting must be done at a time when the stock and scion are in the appropriate physiological state to allow a greater percentage of takes. The preferred grafting methods are side grafting and cleft grafting. The optimum state for selecting vegetative material (scions) is when the tree is dormant, i.e. when the plant sheds all its leaves; this generally occurs during the summer. To select scions during the winter, the shoots need to be ringed eight to ten days before grafting. The stocks must be approximately 1 m high, 1.2 cm thick and nine months old. It should be borne in mind that the cuts in both the stock and the scion have to be made in the most uniform area of both barks so that the join is complete. Once the operation is completed, the graft is tied with special tape and a little melted paraffin wax is applied for protection.
A week later, the apical part of the stock is cut, leaving 30 cm between the shoot and the graft. This step is repeated after two weeks when only the graft is left. At approximately two months, the part of the plant which has joined to the stock begins to bud. At four months. the tape is removed in order to let the new shoot develop freely and, two months later, the plants can be planted out in the field.
Present cultivation situation. Central America is going through a difficult economic situation. and this is reflected in the agro-industrial sector. An economic recovery is needed that involves investments in non-traditional products. The sapote may be quoted as an example of a nontraditional species which offers economic potential for agricultural diversification in the region and hence for achieving a better ecological balance. In Central America, South America and the Antilles, interest in this crop is a recent development. There are just a few small commercial plantations and isolated trees on uncultivated land which may allow the crop to be promoted both at a local level and for export.
In these regions, there are no germplasm collections and few skilled technicians for carrying out the technological transfer of cultivation. Furthermore, Central America has climatic. topographical, soil and social characteristics which could allow this genetic resource to be developed and utilized more fully. In spite of its potential benefit for growers and industry. there is still little information and research being done on exploitation and use of the sapote.
A better knowledge of the genetic diversity, seasonal variations in production, quality, supply of and demand for this species would enable its monoculture, or cultivation together with other perennial crops, to be encouraged.
The future of sapote cultivation is linked to the selection of the best genotypes for each country. Selection criteria will have to be based on the vigour, height and build of the trees, the production, shape and size of the fruit, the quantity of flesh and fibre and the aroma and flavour. The requirements of internal and external markets will need to be studied and the selling prices of specific cultivars compared.
Establishing the sapote may be a slow process and will require research, time and investment. Experience with other crops shows that, without adequate marketing and sustained development strategies, growers may stand to lose. Indeed, they do not usually know the quality standards which apply to production, nor the methods for effective husbandry, and also have to cope with high harvesting costs, low prices paid for the product. small yields and a shrinking market. It should be stressed that research, commercial production and marketing are the key factors for successfully establishing non-traditional crops.
When starting to develop a crop such as the sapote, an evaluation needs to be made to demonstrate its prospects for adoption by growers. Consideration will have to be given to the area of adaptation, the availability of land, bank credit, production costs, market security and probable net income for the grower; these factors will have to be compared with those of other competitive crops. Information will also have to be collected on the availability of outstanding genotypes' stock and graft nursery capabilities and cultivation practices, as applied to the seedling and in the field.
Coordination between production and marketing is essential if a new product is to be presented successfully. If the market is created before production meets demand, buyers may show a lack of interest and the product may lose its acceptability. If production exceeds demand, growers may be disillusioned by the losses and, in some cases, may even change crops.
With regard to the potential areas for a crop's introduction and cultivation, priority should be given to sampling genetic diversity. This stage can take at least two years, depending on the availability of germplasm. For species that are widely dispersed or located in geographically or politically inaccessible areas, collections may continue indefinitely. Permanent collections need to be established while finance must be made available for the preservation of those that already exist.
From the social point of view, it is worth stepping up the propagation of this crop and making its nutritional benefits available to low-income rural populations. From the economic point of view, the export of the dried fruit or flesh would bring enormous advantages to these groups, since it would constitute an inflow of foreign exchange. Ecologically, this species could be combined with other perennial crops such as cocoa and coffee, thereby providing emergency income for the grower should the market price of the main perennial species decrease or fluctuate constantly.
Six stages may be envisaged in research and development:
To carry out this programme, credit needs to be made available with acceptable rates of interest and repayment terms, while there must also be the political will to ensure implementation and technical support up to the marketing stage.