Sapote (Pouteria sapota)
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Botanical name: Pouteria sapata
(Jacq.) H. Moore & Steam
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 free 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 purée 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 protrusion 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 carpets.
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.
Ecology and phytogeography
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 15°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 2 500 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), (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.
FIGURE 9 Sapote (Pouteria sapota): details of a cross-section and shapes of the fruit
TABLE 4 Characteristics of the best sapote cultivars in Florida, 1991
|Abuela||October-November||740 - 2 400||Red||Excellent||Regular|
|Area No 3||July-September||400- 740||Pink||Good||Regular|
|Chenox||May-June||400 - 850||Pink||Good||Regular|
|Copan||July-August||425 - 900||Red||Excellent||High|
|Florida||March-April||400- 1 130||Reddish||Good||High|
|Francisco Fernandéz||August-September||560 - 700||Reddish||Excellent||Regular|
|Magaña||April-May||740 - 2 400||Pink||Good||High|
|Navidad||December||400 - 740||Salmon||Excellent||High|
|Patin||July-August||400- 1 130||Reddish||Excellent||Regular|
|Piloto||August-September||400- 7 401||Reddish||Excellent||Regular|
1) This cultivar has a second harvest between July and August.
Much of the generic variability of the genus Pouteria is found in the tropical Sorest 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 'tones 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 he 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.
Prospects for improvement
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:
· exploration for, and collection of, germplasm;
· observation and selection of cultivars for domestic consumption and export;
· chemical studies and use;
· evaluation and agronomic validation;
· production and processing for local consumption and for export;
Experiments on evaluation and agronomic validation must be carried out in various locations and environments and should include cultivation practices, harvesting methods, yield and quality. A high genetic diversity must be maintained so as to select the genotypes suitable for each environment.
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.
Almeydan, N. & Martin, F.W. 1976. Cultivation of neglected tropical fruits with promise. Part 2. The mamey zapote. ARS-S- 156. Washington, DC, USDA.
Campbell, C.W. 1967. The mamey sapote in southern Florida. Proc. Fla. State Hortic. Soc., 80: 318-320.
Campbell, C.W. & Lara, S.P. 1982. Mamey sapote cultivars in Florida. Proc. Fla. State Hort. Soc., 95: 114-115.
Gutiérrez, G. 1984. Técnicas de injertación en sapote (Calocarpum sapota Jacq.). Proyecto de Recursos Fitogenéticos. Turrialba, Costa Rica, CATIE/GTZ.
Kulwal, L.V., Tayde, G.S. & Deshmokh, P.P. 1958. Studies on softwood grafting of sapota. PKV, Res. J. (India) 9(2): 33-36.
Lazo, F.R. 1965. El injerto del mamey colorado. Arroz (Colombia), 14(148).
Malo, S.E. 1970. Propagation of the mamey sapote. Proc. Trop. Reg. Am. Soc. Hortic. Sci., 18: 165-174.
Morera, J.A. 1982. El zopote. Genetic Resources Unit. Turrialba, Costa Rica, CATIE/GTZ.
Ogden, M.A.H. & Campbell, C.W. 1981. Canistel as a rootstock for mamey sapote. Proc. Trop. Reg. Am. Soc. Hortic. Sci., 93: 133-136.
Pantin, D. 1991. Mamey feature. Pantin's mamey conservations with Donald Pantin, mamey grower. Trop. Fruit World, 2(1): 2- 17.
Pennington. 1990. Sapotaceae. Flora neotropica.
Quilantan Carrero, J. 1979. Propagación vegetativa del mamey zapote. Proc. Trop. Reg. Am. Soc. Hortic. Sci., 23: 180-182.
Whitman, W.F. 1966. The green sapote, a new fruit for South Florida. Proc. Fla. State Hortic. Soc., 78: 330-336.
Woot-Tsuen, W.L. & Flores, M. 1961. Tabla de compositión de alimentos para uso en América Latina. Guatemala, INCAP.
Spanish plum, red mombin (Spondias purpurea)
Botanical name: Spondias
Common names. English: Spanish plum, red mombin; Nuhuat:. ateyaxocotl; Spanish. jocose (Mexico [Oaxaca], Central America), ciruelo(Mexico[Jalisco,Yucatán])
Spondias purpurea was grown widely from Mexico to the northern region of South America when the Europeans arrived, as can be deduced from the descriptions of the first chroniclers (Oviedo, Sahagún). It spread through the Antilles and the rest of South America and was possibly taken from Mexico to the Philippines. The fresh fruit has a very pleasant taste and its consumption is increasing. It is a valuable but economical raw material for the preparation of soft drinks, preserves and syrups and is also eaten as a dried fruit The current marginalization and scarcity of commercial plantations are largely due to a lack of attention on the part of` producers, technical experts and agricultural extension workers, who are concentrating their efforts on other fruit-trees in greater demand on the foreign marker.
The most widespread use of S. purpurea is as a fresh fruit for local consumption and for supplying city markets. In Mexico and Guatemala, it is used in other forms which are possibly of post-Hispanic origin. In one form, the fruit is boiled in brine for five to ten minutes and then dried in the sun, either on tables with a wire mesh or reeds for three days or on driers on mobile units for ten to 12 hours. By this process. the dried fruit is reduced to one-quarter of its fresh volume. Another way to prepare the fruit is to heat it in unsalted water and dry it in the sun, while a third process. used in Mexico to obtain ciruelo negro, consists of pricking the skin of the fruit, placing it in syrup (I kg of sugar in a bottle of water) and letting it simmer until the sugar burns or becomes concentrated. Ciruela cristillina is a fourth method of preparing the fruit' similar to the previous one, only the fruit is gathered while it is ripening and is boiled for a shorter time.
Other uses of Spondias pulp include as an atole, mixed with maize flour and sugar, and in the preparation of wine, chicha (maize liquor) and soft drinks.
Analyses of the fresh fruit show that the percentage of moisture in the flesh ranges from 76 to 86 percent; it is very low in protein and fat and contains appreciable quantities of calcium, phosphorus, iron and ascorbic acid.
Its consumption is currently increasing throughout Mesoamerica. The bulk of production comes from isolated trees or hedges, while very little comes from well-ordered and maintained plantations, such as the ones seen around the city of Oaxaca. However, it is a very promising fruit-tree because it is accepted on the market; it is a hardy species with a high resistance to drought; it is easy to produce on poor soil; and its propagation is exclusively vegetative, which ensures an early harvest.
S. purpurea is a small tree, growing 4 to 8 m, with a broad crown, irregular trunk and fragile branches; its leaves are composed of five to 12 pairs of elliptical-acute leaflets, 2 to 4 cm in length and which fall before the flowering period. It has red flowers in 3 to 5 cm panicles, situated along the small branches; the fruit is an irregular oval drupe, somewhat gibbous, smooth and shiny, 4 to 5.5 cm long and a violet to yellow colour, with a woody kernel which contains the seeds. The flesh is sparse, creamy, yellowish and bitter-sweet in the cultivated plants and very acid in the wild plants. It contains malic acid, sugar, calcium malate and starch. The growth cycle has only been studied in Mexico, in Sinaloa and Puebla. In Sinaloa, the trees have foliage from June to October, leaves fall from October to December and the trees are without foliage from January to May. Flowering occurs in February and March and fruiting in June. In Puebla, the trees have leaves from March to October, leaf fall occurs from October to December and the trees remain leafless from January to April. Flowering takes place from December to January and the fruit ripens in April and May. Of great interest is the absence of seed formation in this species, an aspect that was first studied in the Philippines. In the "nut", which occupies the central part of the fruit, only remnants of aborted seeds are found. This is due to both poor pollen formation and the oosphere. Natural distribution is thus completely limited, but the ease with which stems and branches sprout, together with their fragility, allows a very limited natural propagation. Recognition and conservation of the numerous variants which this species displays is possibly due to the action of humans.
Ecology and phytogeography
The natural populations of S. purpurea grow from sea level to an altitude of 1 200 m in areas with alternating seasons from Sinaloa and Jalisco in Mexico to Colombia. It is known that S. purpurea was taken from Nicaragua to Panama and South America in the form of cuttings with a viability of several weeks. It grows in regions of low humidity and remains leafless during the dry season. It has been introduced into similar tropical regions in Southeast Asia and also in subtropical areas (Florida).
Numerous clonal varieties of S. purpurea are known, but there has been no formal characterization of them. In Yucatan there are 20 varieties and, although some may be S. lutea, this is perhaps the most notable varietal concentration in Mesoamerica. Ak-abal, with small, poor-quality fruit and smooth succulent roots, like those of the Brazilian species S. tuberosa is used for pickles. The cultivated varieties may be divided into two groups:
Summer mombin. This fruits (in Central America) during the dry season from February to May, has ellipsoidal fruit that is 2.5 to 3 cm long with smooth, purple-red skin and yellow, smooth, sweet and slightly acid flesh. When green, these varieties look like olives. The varieties Tronador, Criollo, Nica and Morado grow between 0 and 800 m.
Winter mombin. This is of superior quality, with fruit that is 3.5 to 4.5 cm long, red or yellow, smooth or with protuberances, and has firm, sweet, slightly acid flesh. It ripens at the end of the rainy season (September to December). Most of these varieties grow between 800 and 1 200 m and those known include Petapa, Corona and Cabeza de loro.
It has been suggested that these two groups should be considered as different species, but their distinctive characteristics are within the normal varietal range in the cultivated species. Wild populations, such as the iguana mombin in Costa Rica, have very attractive, red or purple fruit. with yellow flesh similar to certain grapes. although it is acidic and astringent. There are other wild varieties in Central America. some with common names. Being a species in which crossings must be very difficult neither varietal richness nor related species. such as the jobo (S. lutea). are of great use in genetic improvement.
FIGURE 10 Spanish plum, red mombin (Spondias purpurea)
On the other hand, the study and evaluation of clonal variation may offer new material. In this connection, regions of particular interest are: the Pacific area of Nicaragua which has been been famous for its mombin or Spanish plum since the days of colonial settlement: Yucatan. where numerous varieties exist: and southwestern Mexico and the neighbouring region of Guatemala. There are no collections of germplasm. but they should not be difficult to establish and maintain. In addition to S. lutea, there are two cultivated species: ambarella. Jew's plum or golden or Otatheite apple (S. dulcis) from Polynesia, which is grown sporadically in tropical America; and imbu mombin (S. tuberosa) from the dry region of northwestern Brazil, whose fruits are of excellent quality. These three species are propagated by seed.
Being a vegetatively propagated species, the sowing material consists of straight cuttings, more than 6 cm thick and at least 1.5 m long, with horizontal cuts. They are cut at the start of leaf production which generally coincides with the beginning of the rains. The cuttings are kept in the shade for a couple of weeks and are planted 8 x 8 m apart at a depth of 30 cm. As a rule, the only cultivation practice is pruning of the branches to cause numerous shoots to form along the main branches. Pruning can be done every year, since the flowers bud on the current year's branches. The experience of producers in Mexico is that pruning increases the size and weight of the fruit.
In Oaxaca, there are commercial plantations on which the trees are pruned at a height of 2 m: the cuttings are planted in double. inclined rows, with 3 m between the pairs of rows when pruned, they look like European apple orchards.
There are no serious pests apart from the Mediterranean fruit fly (Ceratitis capitata) and Mexican fruit fly (Anastrepha ludens) which cause serious damage.
Harvesting on the pruned trees is an easy operation, performed by shaking the branches with poles or sticks; the fruit is gathered from the ground. Throughout the region where mombin is produced, the green fruit is eaten a great deal, as is the green fruit of the ambarela (S.dulcis).
Prospects for improvement
S. purpurea can be grown on marginal land of low agricultural value, on which the tree could be used for reforestation and produce extra profit for growers. Its production season is short. and late or early varieties that extend this period must be sought. Marketing, whether locally or in major towns, does not pose any major problems, as it is a widely accepted product.
The main limitation is attack from fruit files since control is expensive and beyond the range of small producers. An evaluation of cultivars that have some degree of resistance would be very advantageous, as would agronomic measures that tend to reduce infection by flies. Another theme to be investigated is the effect of defoliants on the acceleration of fruit formation.
So tar, there has not been any industrialization of the fruit. Improving the primitive processes described earlier and research into others, as has been done in Florida with the artificial drying of slices of the flesh, may open up new possibilities for consumption.
Varieties of S. purpurea urgently need to be collected in one or more gene banks, which allow a quick evaluation of their genetic characteristics (resistance to insects, production period, response to pruning), and sowing material must be distributed among growers. In areas with sufficient space, it is recommended that S. purpurea be planted as a hedge since its fruit production represents extra profit for the grower. Finally, transport and packaging problems must be studies to see how they can be improved since they are at a very primitive stage.
Barrios, D.C. de la C. 1972. Observación de poda en ciruela tropical. Simposio sobre la investigación, el desarrollo experimental y la docencia de CONAFRUT.
Carbajal, C.E. & Castro, M.M. 1981. Evaluation del diámetro y la altura de la estaca en la propagación del ciruelo mexicano (Spondias purpurea L.) en CONAFRUT de Rosario, Sinaloa Mexico, SSIDED, CONAFRUT.
Hernández, L.A. 1977. Estudio sobre identification y selectión de criollos sobresalientes en ciruelo mexicano (Spondias purpurea L.) en el Estado de Veracruz. Mexico, SSIDED, CONAFRUT.
León .1. & Shaw, P.E. 1990. Spondias the red mombin and related fruits. In S. Nagy, P.E. Shaw & W.F. Wardowsky. eds. Fruits of tropical and subtropical origin p. 116- 126. Lake Alfred, Florida. FSS.
Manjarrez, M., Tisnado, N. & Carbajal, G. 1980. Fertilización en ciruela mexicana (Spondias purpurea L) Rosario. Sinaloa, Mexico, CONAFRUT-SARH.
Martínez, B.A.1988. Efecto de defoliantes en la producción temprana de ciruela mexicana (Spondias purpurea L.) en San Bernardo Acatlán, Puebla. Chapingo, Mexico, UACH. (thesis)
Martínez, L.C. 1988. Problemática y programación de la asistencia técnica en el cultivo de la ciruela mexicana (Spondias purpurea) en el Municipio de San Jerónimo Xayacatlán, Puebla. Chapingo, Mexico, UACH. (thesis)
Nava-Kuri, G.G., & Uscanga, M.1979. Estudio físico y químico de doce tipos de ciruela (Spondias sp.,) en el Estado de Veracruz. Proc . Trop Reg. Amer Soc . Hort. Sci., 23: 132- 136.
Souza Novelo, N. 1949. Los ciruelos de Yucatán. Bol., Soc . Bot. México . 9: 5- 12.
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