Bridg, Hannia: Micropropagation and Determination of the in vitro Stability of Annona cherimola Mill. and Annona muricata L.

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Chapter 1. Botanical and Cultural Aspects
Introduction

Annona cherimola and Annona muricata belong to the family Annonaceae. These subtropical and tropical trees are part of the natural flora in Central- and South- America. The medicinal and nutritional uses have been exploited by the Indians before the discovery of this continent. In America these fruit species have been preserved by tradition, but are still unknown as crop plants.

The commercial acceptance of A. cherimola and A. muricata as exotic fruits is widespread worldwide, therefore there is a rising interest to expand A. cherimola and A. muricata plantations in countries where these plants have been introduced such as Australia, California, Chile, Israel and Spain. These countries promote technical knowledge in terms of plantations, marketing and industrialization which is deficient in the countries where these plants are part of the native flora such as Colombia, Peru, Ecuador and the Caribbean Islands.

The yield potential of A. cherimola and A. muricata in Colombia, Venezuela, Brazil and Peru is promising. In 1992 Colombia reported 1,134 ha planted of A. muricata and predicts 16,499.420 kg of fresh produced pulp for 1999, furthermore as far as it is known there are no established technical plantations with A. cherimola in Colombia. Chile, the leader in South America of A. cherimola, expects a rising promedium of 7,500 tons per year. A. cherimola is growing on 2,500 ha in the south of Spain with promising perspectives in the fruit market of the European Community.

The current chapter presents a review of the basic botanical and culture information regarding A. cherimola and A. muricata as a product of the compilation of isolated world publications.

1.1 Annona spp.

The family Annonaceae Juss., covers more than 130 genera with more than 2000 species, grouped taxonomically, widespread in the subtropics and tropics (Watson and Dallwitz, 1992). Of them 17 genera are distributed in tropical areas. Only four genera, Annona, Rollinia, Uvaria and Ansimina produce edible fruits (Samson, 1986).

The genus Annona L. Syst. ed. I. (1735) comprises around 120 species, as well as a number of hybrids commonly referred to as „Atemoyas“. The species of this genus are one of the most delicately flavoured fruits when properly ripened. The flesh has a pleasant blend of sweetness and mild acidity with a consistency of baked custard. This latter characteristic is the reason why Annonas fruits are called indistinctly custard apple or sugar apple and confused with each other frequently (Table 1) (Lizana and Reginato, 1990). The term Annona etymologically derives from the Latin Annona (yearly produced) (Bourke, 1976) .


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Table 1. List of the most well-known species of the Annona genus and their popular assigned names in several languages

Species

Known

 

 

Annona cherimola Mill.

Annona blanca, Annone, Anone, Cachiman la Chine, Cherimolia, Cherimolier, Cherimoya, Cherimoyer Frucht, Chirimoya, Chirimoyabaum, Chirimoriñon, Custardapple, Graviola, Jamaikapfel, Pac, Pap, Peruanischer Flaschenbaum, Poox, Poshte, Pox, Rahmapfel, Tsummy, Tukib, Tzumus, Zuckerannone

Annona diversifolia Stafford

Annona blanca, Chirimoya de las tierras bajas, Ilama, Ilama-zapote, Papauce

Annona reticulata L.

Annona colorada, Bullock‘s heart, Cachiman, Corazón de buey, Custard apple, Mamon, Manzana de ilán, Netzannone, Ochsenherz, Rahmapfel, Ramphala, Reticulata

Annona squamosa L

Anón, Annona blanca, Annone écailleuse, Aritium, Ata, Attier, Cinnamon apple, Corossolier écauilleux, Custard apple, Fruta de conde, Noi-na, Pinha, Pomme canelle, Rahmapfel, Riñón, Saramuyo, Schuppenannone, Sitaphal, Sugar apple, Sweetsop, Zimtapfel

Atemoya *

Atemoya, Chirimorriñón, Custard apple

Annona purpurea L.

Cabeza de Negro, Catigüire, Manirote, Soncoya

Annona glabra L

Anona lisa, Chirimoyo de los pantanos, Pondapple

Annona montana L.

Cimarrón, Guanábana de las montañas, Mountain soursop,

Annona muricata L.

Anona de broquel, Anona de puntitas, Araticu-ponhé, Cachiman épineux, Catucho, Coraçao de Rainha, Corosol, Corosol épineux, Corosselier, Durian benggala, Durian blanda, Durian maki, Graviola, Guanábana, Guayabano, Huanábana, Jaca do Pará, Nanqka, Nangka blanda, Nangka longa, Prickly-custard apple, Sauerapfel, Saure sobbe, Seki-kaya-belanda, Sinini, Sorsaka, Soursop, Stachelannone, Sauersack, Sour apple, Toge-Banreisi, Thu-rian-khack, Zapote agrio, Zapote de viejas, Zuurzah

The underlined words emphasize the most popular assigned names of the particular species
Atemoya, is a hybrid between (Annona cherimola x Annona squamosa)
Source : Gandhi and Gopalkrishna (1957), Bünemann (1973), Popenoe (1975), Bourke (1976), George (1984), Sanewski (1988), Gardiazabal and Rosenberg (1988), Lizana and Reginato (1990), Leal (1990) and de Feo (1992).

The most important species of the genus are Annona cherimola Mill., Annona muricata L., Annona squamosa L., Annona reticulata L., and the interspecific hybrid Atemoya (A. cherimola x A. squamosa) (Sanewski, 1988). Annona diversifolia Saff and Annona montana Macfad. are also important in some countries, but their production chiefly takes places in private orchards. All of them have one thing in common, they are composite fruits, made up of scaly sections that grow together in fir-cone fashion (Samson, 1986).


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1.2 Annona cherimola Mill., Gard. Dict. ed. 8 No. 5 (1768)

Synonyms Annona pubescens Salisb

Annona tripetala Aiton.

The A. cherimola, native to the Ecuadorian Andes, is the most appreciated subtropical fruit tree in the Annona genus. (Schroeder, 1956; Farre and Hermoso, 1987; National Research Council, 1989; Correa and Bernal, 1989; Calzada, 1993). The cherimola has long played an important role in the life of the Incas. Terracotta vases modelled after cherimoya fruits have been unearthed from prehistoric graves in Peru.

The A. cherimola around the world has acquired only few colonial names, which are only merely variations of the original Quechua<1> word Chirimoya. The Chilean B. Vicuña Mackenna (1875) interpreted from Quechua language the word “chirimoya“, where “chiri“ means cold and “moya“ means seed, sinus or rounded. He wrote in Spanish the translation “seno frio de mujer“ or “cold breast of woman“ in English (Gardiazabal and Rosenberg, 1988)

1.2.1 Origin and Distribution

The A. cherimola is native of the Ecuadorian Andes, South America, (Farre and Hermoso, 1987). It is an important backyard crop throughout Colombia, Ecuador and Peru (Figure1). It has been grown since prehistoric times by Indians from Mexico to Chile. Chileans consider the cherimoya to be their „national fruit“ and produced it (notably in the Aconcagua Basin) on a considerable commercial scale (Corfo, 1984).

In other cooler regions of South America such as Bolivia in the department of Cochabamba and surrounding areas the crop flourishes well. In Argentina, the cherimoya, is mostly grown in the province of Tucuman. In Brazil, it is naturalized in the highlands. In other countries of Central America like Guatemala, El Salvador, Costa Rica, Nicaragua, Honduras and Mexico the plant has been naturalized in temperate zones (National Research Council, 1989).

In 1790, the cherimoya was introduced in Hawaii and naturalized on dry upland forests. In 1785, it reached Jamaica and Haiti, where it grows at an altitude ranging from 1,066 m to 1,524 m SL. In the United States, seedlings from different regions were planted in small sections of Southern California and Florida with some difficulties, because cherimoya is not frost tolerant (Morton, 1987).

At the Mediterranean it was introduced by the Spanish conquerors and employed as dooryard. In the province of Granada it gained importance in the 1940s when replacement of the old orange trees in the Sierra Nevada mountains started. Actually, Spain is one of the biggest producers of cherimoya fruits. There are also widespread small cherimoya plantations in Italy -province of Reggio Calabria-, Portugal, Madeira (Constantino, 1963; Behr, 1992), Canary Islands, Algeria, Egypt, Israel, Libya, Eritrea and Somalia. In Thailand, Indonesia, Java and the Philippines scattering Cherimoya


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trees can be found where it is well adapted to lower altitudes (750 m). It was introduced into India and Ceylon in 1880 and there is a small-scale culture in both countries between 457 m and 2,134 m SL., (George, 1984; Morton, 1987; National Research Council, 1989; Behr, 1992).

Figure 1. World distribution of Annona cherimola

1.2.2 Description

A. cherimola is a subtropical, erect and low branched tree (Figure 2), somewhat shrubby or spreading (5-9 m). It has greyish pubescent young branchlets. The leaves are briefly semideciduous (just before spring flowering), alternate, 2-ranked, with minutely hairy petioles (6-12 mm), its form is ovate to elliptic or ovate lanceolate, short blunt-pointed at the apex, slightly hairy on the upper surface, velvety on the underside, and measures between 7-15 x 3-9 cm (Figure 2).

The fragrant flowers are dichogamous, protogynous, often opposite to the leaves. They occur in most cases on one-year branches, on new shoots and in older wood. The number of flowers is variable, up to three flowers can be produced on each bud site. The flowers appear solitary or in clusters (2-3), nodding on short peduncles. They are long and narrow, about 2.5 cm long, with brown or yellowish tomentose outside. The outer petals (6) are three-parted and narrow, the inner ones small and scale-like.


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Figure 2. Aspect of Annona cherimola tree, flower, fruit and plantation


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The calyx is tubular. The stamens are numerous with fleshy filaments bearing long, adnate, spiral anthers. The pistils are great in nummer, ovuled, crowded on an elongated receptacle (Figure 2).

The cherimoya fruit is composite, formed by fusion of many carpels, conical or somewhat round, apple- or heart-shaped, 10 - 20 cm long and up to 10 cm in width. Its weight ranges between 200 - 600 g. The greenish yellow purple skin is thin or thick, may be smooth with bumps or oblong scales, which overlap each other like roof tiles or fingerprint depressions with a form a complete outer case. It is easily broken or cut open. Pulp is creamy white, juicy flesh and has a pleasant aroma and tasting, sour-sweet flavour, contains numerous hard, brown or black, bean-like, glossy seeds (1-2 cm), which are inedible. The fruit is ripe when the skin begins to blacken (Figure 2) (Bourke, 1976; Morton, 1987)

1.2.3 Bloom, Harvest and Storage

The A. cherimola has a dichogamous protogynous flowering behaviour (Figure 3). Flowering is strongly associated with vegetative flushing, with most flowers being produced on the basal nodes of newly emerging vegetative laterals (George and Nissen, 1987a). When the tree is in the flowering stage, all carpels must be pollinated to produce full shaped fruits (Lizana and Reginato, 1990). Fruit set and yield of A. cherimola is affected by ineffective pollination (Venkataratnam, 1959; Blumenfeld, 1975).

Figure 3. Dichogamous protogynous flowering behaviour on A. cherimola Mill.

Incomplete pollination bears also the risk of shapeless fruit and yield decrease (Thomson, 1970). Flowers are unable to self pollinate (McGregor, 1976), because the male and female organs do not mature simultaneously (Schwarzenberg, 1946). Furthermore flowers are not attractive to insects. However, Thakur and Singh (1965) and Gazit and Eisenstein (1985) reported the presence of Nitidulis spp., fruit beetles, which are promoting in natural conditions cross pollination. The commercial production


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of cherimoyas actually depends upon fruit management in relation to artificial pollination (Sainte Marie, 1987). Campbell (1979) and Saavedra (1979) tested the use of gibberellic acid (GA3) and indole-3-acetic acid (IAA) on several Annona species. Of these species the A. cherimola did not show a positive response however, in the hybrid Atemoya (A. squamosa x A. cherimola) increased the production of seedless fruits.

The first fruits appears about 100 days after blooming, fruit growth follows the typical sigmoidal pattern, it takes about 9 months in Chile to obtain a ripe fruit (Saavedra, 1979). The A. cherimola fruit is best harvested, while it is began to turn in color and is still firm. If it is picked too green, the fruit will soften properly, but its quality is reduced. Sometimes, near to the stem, fruits are waxed to hasten ripening and to improve the custard-like flavour (Thomson, 1970).

This fruit must be eaten within a few days after harvesting (Teubner et al. 1990). Maturity is reached when the fruit has grown to its maximum size, changed in colour of middle green to lighter green or yellowish-green (Reginato and Lizana,1980).The cherimoya is a typical climateric fruit during ripening (Biale et al, 1954; Kosiyachinda and Young, 1975; Delcura et al. 1996). It ripens quickly and may be deteriorated after eight days (Reginato and Lizana, 1980).

The skin browning increases after harvesting, but this is not related to chlorophyll decrease in concentration (Martinez et al, 1993). The variation of the skin colour depends on the concentration of phenolic compounds and the activity of the polyphenoloxidase, which catalyzes the oxidation of these phenols to o-quinones whose are promoting spontaneously a dark-colored melanine (Coseteng and Lee, 1987; Martinez-Cayuela, 1988).

Cherimoya can be transported short distances at room temperature 18 ± 2 °C and should be protected from rub. When the skin becomes bronze yellow and the peel is susceptible to fall off, handling becomes almost impossible (Lizana and Reginato, 1980). The shelf-life of the fruit is short at 20°C it is less than one week. This characteristic limits the excellent potential marketing of cherimoya far away from the plantation points (Brown et al, 1988).

Low temperatures during transport cause chilling and several injures. The cherimoya is not cold resistant and does not tolerate frozt. However, the cold susceptibility differs between cultivars. Low temperatures on refrigerated storages cause chilling injuries on A. cherimola fresh fruit (Fuster and Prestamo, 1980). Symptoms of chilling injury include, skin darkening, failure to ripen properly, pulp discoloration and the appearance of pale pink vesicles around the seeds (Gutierrez et al, 1992). Changes in total soluble solids and tissue pH in the mesocarp may constitute a biochemical way to assess the occurrence of chilling injury in stored cherimoya fruits (Gutierrez et al, 1994). Refrigerated storage proves not effective in prolonging the postharvest life of cherimoya fruits since they do not withstand temperatures below 10-13 °C without developing chilling injury symptoms (Gutierrez et al, 1992; Fuster and Prestamo, 1980).

Temperatures in a range of 10 ± 2 °C prolong the postharvest life of the cherimoya fruits. The A. cherimola cv. Concha Lisa can be maintained at 10 °C with 5 % O2 for 43 days and still ripen normally. It remains acceptable after 4 days at room temperature (Palma et al, 1992; Alique, 1995). Commercialization of cherimoyas will be possible if ships are equiped with controlled or modified atmosphere chambers rather than fresh air, but little is known about the response of cherimoyas to controlled atmosphere (Kahn, 1983; Palma and Stanley, 1993). The response of A. cherimola to cold storage


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and waxing have been reported by Lizana and Ararrázabal (1984). Wax allows fruit quality preservation, decreases water loss and stimulates flavor during strorage.

1.2.4 Cultivars

There is a great diversity of Annona cherimola due to two factors: Its nature as hermaphrodite, dichogamous-protogynous species and natural regeneration through seeds (George, 1984). Thus numerous selections have been made from A. cherimola seedling populations. Conventional plant breeding methods have been applied to improve the cherimoya fruit quality. Selected cherimoya plants are maintained in germplasm orchards by grafting. California, Chile and Australia. Each selection or cultivar is described according to phenotypic characteristics, tree growth and development, type of fruit, weight, number of seeds, quality of pulp and production (for details cf. Cordoba, 1967; Thomsom, 1970; Ibar, 1979; Tijero, 1992; Sanewski, 1988; Gardiazabal and Rosenberg, 1988)

The external appearance, surface and colour of the fruit is also used to distinguish some selections in Spain and Colombia (Figure 4; Table 2 ) (Bourke, 1976; Tijero, 1992). New Zealand reports 223 cultivars of A. cherimola, of them only 16 are the promising (Sanewski, 1988). In 1988, Chile introduced 18 cherimoya cultivars (Gadiazabal and Rosenberg, 1988) (Table 3).

Figure 4. Classification of some Cherimoya fruits by the surface appearance (Tijero,1992)


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Table 2. A. cherimola cultivar characterization by fruit appearance

Cultivar

Surface Appearance

Characteristics

 

 

 

Smooth - Loevis - Lisa

Free from obstacles and hairs

One of the finest of all, sweet, juicy and relatively free of seeds. Ideal to transport

Fingerprint - Impressa

Lines on the tip of a finger or thumb or heart. Smooth surface,

__________

Umbonata

Sharp Bulging, swelling, several carpels. The skin is thick

Pulp acid and numerous seeds. Is ideal to prepare cooling drinks and sherbets

Mammillata - Tetillada

Defined fleshly hard nipple-like protrusions, during ripe. The distal area is smooth and the basal area is nipple-like

Common in India and Madeira island. One of the best forms

Tuberculata

Conical protrusions and wart-like tips during ripening

Common in Peruvian markets. Preserved in prehistoric potteries from the graves of the Incas

Source : Thomson, 1970; Ibar, 1979 and Tijero, 1992

Table 3. The most promising cultivars of A. cherimoya around the world in 1999

Country

Cultivars

 

 

Australia

Andrews *, Kempsey *, Mossman *

Bolivia

Bronceada*, Concha Lisa

California

Arthur, Bays *, Bonita, Booth, Carter, Chaffey, Deliciosa, Bumpo, Golden Russet, Haluza No. 2, Horton, Libby, Lisa, Loma, McPherson, Mira Vista, Oakwood, Ott, Peru 7752, Peru seed No. 24, Pierce, Ryerson, Sabor, Sallmon, Spain,Thomson, Whaley, White*

Chile

Bronceada *, Canaria „canaria clasica“, Capucha*, Concha Picuda, Concha Pesada, Concha Corriente*, Concha Lisa*, Cuero Dechando, Dedo de Dama, Impressa, Juliana, Juniana, Margarita, Piña*, Plomisa, Popocay, Serenense Lisa, Serenense Larga, Terciopelo or Felpa*, Tumba „sandia“ *

Colombia

Amarilla, Blanca, Lisa, Negra, Rio Negro, Rugosa, Tocarema

Spain

Basta, Negrito, Pinchua

New Zeland

Bays Mt, Bronceada Mt, Burtons Mt *, Burtons, Chaffey Mt *, Deliciosa Mt, Favourite *, Favourite Mt, Jete, Kent (PK)*,PK 31 *, P43 Mt, P52 Mt, Piña ,Mt, PK2 Mt, Q Mt, Reretai Mt *, Smoothey, Spain, White

Peru

Asca, Chavez, Chiuna 1, Chiuna 2, Chiuna 3, Conde Concha, Cumbre, Guayacuyán, Lope Concha, Ñamas, San Miguel, Sander

* cultivars with great potential in this country
Source : Richardson and Anderson (1990), Cordoba (1967), Daou and Daou (1991), Dawes et al. (1990), Gadiazabal and Rosenberg (1988), Sanewski (1988), Tijero (1992) andThompson (1970).


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1.2.5 Cultural Aspects

The open-globe pruning is the traditional system for training custard apple trees, owing is it elliptical canopy growth (Sawneski, 1988). This practice is common for many semideciduous fruit trees (Westwood, 1993). The basic framework of the tree is developed over the first four years. From then on, pruning is mainly used to maintain tree shape, restrict size, regulate cropping and rejuvenation of trees. Authors like Thomson (1970), Egelhart (1974), Gardiazabal and Rosenberg (1988) and Sawneski (1988) report field work results on pruning.

A. cherimola is a semideciduous tree, and different growth cycles are recognized, which are influenced independently by the environmental conditions. The semideciduous cycle starts at the onset of low temperatures. The degree of leaf drop depends on the vigour of the tree and the environmental conditions. For example, the relatively dry and cool conditions in Nambour (Australia) increase leaf drop. Leaves that are not shed in the dormant period will usually be dropped by the emerging shoot in spring (Sawneski, 1988).

Since there has been little research on the nutrition of A. cherimola, authors like Sanewski (1988) in Australia, Tijero (1992) in Peru and Gardiazabal and Rosenberg (1988) in Chile based their recommendations on field studies.

The A. cherimola crop seems to depend on mycorrhizae (arbuscular) for optimal growth, in combination with Glomus deserticola. The mycotrophic character of A. cherimola has been described for the first time by Azcon-Aguilar et al. (1994).

The adjustment of fertilizer rates, in particular nitrogen and potassium, is necessary in order to obtain a moderate level of tree vigour. Applications of nitrogen just prior to and after the beginning of flowering appear to enhance fruit set (George, 1988).

The optimum leaf nutrient levels have not been precisely determined for A. cherimola and other custard apples. Sanewski (1988) presented suitable approximations that should be used as a guideline only (Table 4).

For determination of the fertilizer needs for established trees, a leaf analysis is more useful than a soil analysis. Nutritional deficiencies in cherimoya yield crops in Chile have been described by Navia and Valenzuela (1978).

Environment

The environmental variables that limit productivity of custard apples are temperature and humidity (George and Nissen, 1992). Soil and location also have a strong impact on the vegetative development of A. cherimola. Hence, the tree must be protected against frost and strong winds. It benefits from summer rainfall and moderate deep, well drained soils (Table 5).

Under natural conditions the cherimoya appears in the subtropical or mild-temperature highlands of the Andes (1,200 - 2,000 m SL). It does not do well in the lowland tropics due to the subtropical climatic conditions.


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Table 4. Acceptable leaf mineral concentration in Custard apple

Ion

Concentration

 

 

 

Nitrogen

2.5 - 3.0

%

Phosphorus

0.16 - 0.2

%

Potassium

1.0 - 1.5

%

Calcium

0.6 - 1.0

%

Magnesium

0.25 - 0.5

%

Iron

40.0 - 70.0

ppm*

Manganese

30.0 - 90.0

ppm

Zinc

15.0 - 30.0

ppm

Copper

10.0 - 20.0

ppm

Sodium

< 0.02

%

Chloride

< 0.3

%

Boron

15.0 - 40.0

ppm

ppm : parts per million (mg/l)
Source: Sawneski (1988)

Table 5. Ecophysiological optimal requirements of A. cherimola

Climatic Factors

Range

 

 

Elevation

1,200 - 2,500 m SL

Climate

Tropical mild

Temperature

18 - 22 °C

Wind

Moderate

Humidity

60 - 80 %

Soil

Middle-loam

Precipitation

800 - 1,000 mm

PH

6.5 - 7.6

Limitation

Not frost tolerant

The cherimoya tree needs 12-14 hours light period and protection from strong winds and frost. which interfere with pollination and fruit set, especially when carrying a full yield (Sawneski, 1988). In the flowering period hot dry winds cause pollen and stigma desiccation resulting in reduction of fruit set (Duarte, 1974). The fruit skin is also easily damaged by rubbing and long time exposure to dry winds (George and Nissen,1988; Lizana and Reginato, 1990).


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The ambient mild-temperature should be 18 ± 5°C during the vegetative cycle and 10 - 18°C in the semi-dormancy after the harvest. Air temperatures influence leaf and vegetative shoot growth. Leaf size increases dramatically with middle warm temperature (Sawneski, 1988).

In areas where low temperatures are expected trees should be protected because even light frost affect fruit quality (Liebster, 1983; National Research Council, 1989; Behr, 1992). The frost sensitivity is related with the biological cycle which is regulated by several exogenous and endogenous factors (Gardiazabal and Rosenberg, 1988). The tree prefers a rather dry environment and does not grow well in extremely wet conditions. neither where rainfall is spread throughout the year (Sawneski, 1988).

Rainfall between 800 - 1.000 mm3 is desirable. Irrigation is essential in most areas, particularly during the flowering, fruit set and early fruit maturation periods. Water stress during any of these periods can result in flower or fruit drop (George, 1984; George and Nissen, 1992). The cherimoya requires for both flowering and fruit development 60 - 80% humidity (Sanewski, 1988).

Relative humidity below 60% limits fruit set and increases flower shedding (Schroeder, 1943). Humitity superior to 60% influences pollination. Saavedra (1977) and Ahmed (1936) demonstrated that the insertion of a drop of water inside the flower at the time of pollination markedly increased fruit set. However during fruit set high environmental humidity benefits the production of sugars and acids but simultaneously enhance diseases, causing problems during its production (Boshell, 1982. Sanewski, 1988).

The cherimoya tree performs well on a wide range of soils in natural conditions (Farre and Hermoso, 1987). The tree grows not successfully on rocky, highly calcareous soils. Loose and sandy loam and well structured clay loam is suitable (George and Nissen, 1992). Higher yield appears to be obtained from trees grown on sand or sandy loam soil types (George, 1987). At any case the cherimoya needs a soil with good aeration and drainage and does not tolerate water logging (Gardiazabal and Rosenberg, 1988).

A neutral or moderately alkaline soil with pH 6.5 to 7.6 appears to be most suitable (Thomson, 1970). The maximum suitable slope is about 15% to operate efficiently on steeper land (Sanewski, 1988). Soil temperature has a strong effect on the root development and subsequently on productivity. Soil temperatures between 17 and 22°C promote vegetative growth and development and the cherimoya tree increases its production (George and Nissen, 1987; Gardiazabal and Rosenberg, 1988).

The cherimoya tree can be employed in reforestation and soil recuperation programs. Its rustic nature condition and shallow roots are desirable in non-deep soils. This plant is sensible to lack of calcium but not in nutritional demands (Bridg, 1993a).

1.2.6 Pests and Diseases

There are only a few reports on pests and diseases affecting cherimoya trees. Nevertheless, the publications by Chardon and Toro (1934), Gallego (1950), Rocha (1965), Cuculiza and Torres (1975), Raski (1976), Dominguez (1980), Muñoz (1981), Pinochet (1987), Gardiazabal and Rosenberg (1988), Avilan et al. (1989), Martinez and Godoy (1989) Ochoa and Salas (1989) and Tijero (1992), allow to recognize the


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following group of cherimoya pathogens:

Fungi

Ascochyta cherimolaer, Botryodiplodia theobremae, Cercospora annonaceae, Cladosporium carpophilum, Colletotrichium spp., Colletotrichium annonicola, Colletotrichium gloeosporioides, Corticium salmonicolor, Fumagina spp., Fusarium solani, Gloeosporium, Glomerella cingulata, Isariopsis anonarum, Koleroga noxis, Monilia, Nectria episphaeria, Oidium, Phakopsora cherimolae, Phomopsis spp., Phomopsis annonacearum, Phyllosticta, Phythium spp., Phytophtora palmivora, Phytophtora parasitica, Rhizopus nigricans, Rhizopus stolonifer, Rhizoctonia spp., Rhizoctonia solani, Salssetia oleare, Sclerotium rolfsii, Uredo cherimola and Zignoella annonicola.

Insects

Ammiscus polygrophoides, Anastrepha atrox, Anastrepha barandianae, Anastrepha bistrigata, Anastrepha chiclayae, Anastrepha disticta, Anastrepha extensa, Anastrepha fraterculus, Anastrepha oblicua, Anastrepha serpentina, Anastrepha striata, Anastrepha suspensa, Apate monachus, Bactrocera spp., Bephrata maculicollis, Brevipalpus spp., Ceratitis capitata, Cerconota anonella, Coccoidea spp., Emanadia flavipennis, Gelwchiidae spp., Heliothrips haemorphoidalis, Leosynodes elegantales, Lyonetia spp., Oiketicus kirby, Orthezia olivicola, Phyllocnistis spp., Pinnaspis aspidistrae, Pseudococcus citri, Saissetia nigra, Talponia spp., Tenuipalpidae, Tetranynchus spp., and Thrips

Nematodes

Cephalobidae spp., Dorylaimidae spp., Gracilacus spp., Helicotylenchus spp., Hemicycliophora spp., Hoplolaimidae spp., Meloidogyne incognita spp., Pratylenchus spp., Paratylenchus micoletzky. Rhabditis spp., Tylenchorhynchus spp., and Xiphinema americanum.

Algae

Cephaleuros virescens, Cephalosporium spp., Paecilomyces spp.

The CCA „California Cherimoya Association“ has been studying the interaction of some cherimoya pests-diseases and the „benefit control pathogens“ such as: Chrysoperla spp., Cryptolaemus montrouzieri. Cryptolaemus spp., Delphastus spp., Encarsia formosa, Eretmocerous spp., Hyppodamia convergens, Muscidifurax zaraptor, Novius cardinalis, Scolorthips sexmaculatus, Spalangia endius and Trichogramma sp. (Blehm, 1995).

1.2.7 Propagation

The cherimoya can be reproduced gametically by seeds or multiplicated agamically by cuttings, grafting, marcottage. Micropropagation by tissue culture has been introduced in order to reduce time of propagation, but a micropropagation protocol has not as far is known reported (Sawneski, 1988; Jordan and Botti, 1992; Bridg et al, 1994).

The cherimoya seed propagation can be managed successfully. The germination of seeds is satisfactory and the germination conditions have been discussed by Duarte et


14

al. (1974), Toll et al. (1975); Bridg, (1993) and Bourke, (1976). If seeds are kept dry, they will remain viable for several years (Sanewski, 1988). Germination is expected after the third or fifth week. The plants are transplanted when they are 7 to 10 cm high.

Cherimoya seedling plants are heterozygous and a great segregation is observed in plantations of seedling plants (Bridg, 1993a). The tendency of seedlings to produce inferior fruits has given attention to improve vegetative propagation methods (Morton, 1987). Now seed propagation is made principally to produce cherimoya rootstocks. Seedling trees are optimal, if selected germplasm programs are applied to select elite plants (Tijero, 1992).

If propagation of A. cherimola germplasm is made with homozygous plants in which the autofecundation predominates, it is possible to obtain cherimoya clonal lines. Nevertheless, cross pollination does not permit to maintain this process and vegetative propagation must be applied (Thomsom, 1970; Sawneski, 1988).

Cherimoya selections and the other custard apples are propagated generally by grafting, whereby the selected scion cultivar is being attached onto seedling rootstock (Table 6). Thus the scion wood and seeds for rootstock should only be taken from selected trees of known performance (Thomson, 1970).

Seedling plants from cherimoya are budded or grafted 100 to 150 mm above ground level when 12 or 24 months old and dormant, using either a whip, whip-tongue, modified side and cleft graft and then allowed to grow to 1- 1.5 m height before being set out on the field (Morton, 1987).

Table 6. Graft compatibilities between the Annona species

 

Roostock

Scion

Atemoya

A.cherimola

A. squamosa

A. reticulata

A. muricata

A. glabra

A.montana

 

 

 

 

 

 

 

 

Atemoya

+

+

+

-

-

-

-

A. cherimola

+

+

+

+

?

?

-

A. squamosa

+

+

+

+

-

?

?

A. reticulata

?

+

?

+

+

+

?

A. glabra

?

?

+

+

?

+

?

A. diversifolia

?

?

?

+

+

+

?

Symbols : compatible (+), not compatible (-), unknown (?)
Source: Sanewski, 1988

A grafted plant can be produced in about 18 months if a covered propagation shed is used. When plants are grown in the open the process can take two years or more, Grafted trees begin to bear the second or third year after planting (Thomson, 1970; Sanewski, 1988).

Because rootstocks are produced form seeds, there are large differences in performance among individual trees. The rootstock influences the tree vigour but its tolerance is related with the adverse soil and climatic factors. Yield can vary as much as


15

100%. Thus it is possible to increase yield significantly by use of superior rootstock clones (Sanewski, 1988).

Cherimoya is the most suitable rootstock, mainly because of its tolerance to bacterial wilt. Preliminary test showed that cultivars „White", „Deliciosa" and „Kempsey" are moderately tolerant, „White“ is the most cold-tolerant cultivar and so it is considered the best rootstock, but it has the disadvantage of being very vigorous (Sanewski, 1988). In Colombia grafting is not a widespread practice (Bridg, 1993) but the seedlings from A. reticulata and A. montana are used as rootstocks, especially when tolerance against drought and moisture soils to be enhanced (Cordoba, 1967).

In Philippines the species A. reticulata, A. glabra and A. squamosa are reported to be compatible with A. cherimola. In moderate climate areas in Madras (India), A. reticulata is used as vigorous rootstock with 90% success (Bourke, 1976), A. glabra is recommended in Florida (USA) as rootstock in areas with moist soils and it grows better than the graft (Morton, 1987). Grafting between A. cherimola und A. cherimola could be made without compatibility problems, in spite of the slow growth during the first four years, after which the normal tree size is gained (Tijero, 1982).

A. cherimola grafted on A. muricata induces dwarfism, precocity and the fruits are more aromatic. This procedure appears to be very promising, when establishing of new plantations is the objective (Saavedra, 1984). The A. muricata roostocks show a good development in litosolic soils (Tijero, 1992). The grafting of A. cherimola on A. squamosa promotes dwarf trees (Bourke, 1976) and those in North Queensland (Australia) are used as rootstock, because they are more precocious than the cherimoya rootstocks (Sanewski, 1988).

A new propagation technique called „green grafting“ has been developed by CSIRO<2>. It involves grafting of young rootstocks with soft, green shoot tips. This grafting can take place within three to six months after sowing the seed. In Australia it appears to be a promising method because it reduces the nursery time (Sanewski, 1988).

Propagation of cherimoya by cuttings is not a widespread practice, nevertheless the advantages of cuttings include high vigour and higher yields in the first few years of production, more uniform orchards and lower cost of trees. Propagation by cuttings does not produce tap-root plants, making the tree susceptible to blow over by strong winds (Bourke, 1976). The "African Pride"cuttings are not as resistant to bacterial wilt as certain cultivars of cherimoya (Sanewski, 1988).

Cherimoya cuttings (13-15 cm long and 1- 1.25 cm wide) selected from woody branches in the dormancy stage, are recommended to be planted with 4/5 of its length in the ground and 1/5 exposed (Bourke, 1976). Nevertheless, rooting and disease problems limit this practice considerably. Temperature variations combined with hormonal treatments, IBA, IAA and combination of IBA and Rutina have been applied (Duarte et al. 1974; Gardiazabal and Karelovic, 1985; Tazzari et al, 1990).

The hormone indolebutyric acid (IBA) is used as solution or powder to enhance rooting. The combination of 50:50 sand and peat or sand and vermiculite is used for the cuttings bed, which is maintained at 25-28 °C. Then over the 4-6 week the cuttings should start to form a callus and root organogenesis and development will be defined after 8-12 weeks. Cuttings are usually ready for potting after 10-16 weeks. Care should be taken not to damage the roots when cuttings are being removed from the bed, Usually


16

it takes another 6 months before the plants are ready to be field planted (Sanewski, 1988).

George and Nissen (1986) reported notorious increments on the production of Atemoya (A. cherimola x A. squamosa) cv. „African Pride" (18.7 t/ha) and (9.2 t/ha) of A. cherimola, when propagated by cuttings. Flowering, fruit quality and a harvest cycle „two times per year“ were superior compared with the production and development of seedling plants. The benefits of cutting propagation are still under examination. It should only be tried on deep, well-drained soilsand protected areas. A success of 60-80% is common reported with „African Pride", others cuttings e.g. „Pink‘s Mammoth" and cherimoya have proved difficult to root, averaging less than 20% (Sanewski, 1988).

Marcotting (air layering) can also be used with propagated cherimoya cultivars that have been grown from cuttings. Nevertheless cherimoya cannot be propagated easily by this vegetative method. The Queensland Department of Primary Industries, Australia, modified a layering method for propagate cherimoya rootstocks. The roots should develop in four or five months, afterwards the stem can be trimmed and cut from the tree (Sanewski, 1988).

1.2.8 Properties

The cherimoya fruit is used as food product because it can be eaten as a fresh fruit. When fully riped, it is soft to the touch and the stem and attached core can be easily pulled out. The ripe fruit has a fresh pulp, smooth solidity, the taste is sour-sweet and very aromatic, its colour is white (Figures 2; 4).

The fruit may be simply cut in half and the flesh eaten from the “shell“, e.g., with a spoon. In some countries the pulp is pressed and used in combination with other fruits to prepare fresh fruit salad or the flesh is blended with milk or water and little sugar to make juice, desserts, ice cream and tropical fruit cocktails (Liebster, 1983; Benk, 1985 Morton, 1987; Bridg,1993).

Usually the cherimoya pulp is very difficult to process due to it is strong phenolization or browning tendency and can not be used for cooking. However, the industrial products derived from pulp extracts encompass great varieties, ranging from chocolate tablets to cosmetics (Figure 5)

1.2.9 Nutritional Value

The cherimoya fruit contains remarkable amounts of calcium, phosphorus, carbohydrates, thiamine, riboflavin, fructose, glucose, sucrose, cellulose, hemi-cellulose, lignin and peptic substances (Table 7).


17

Figure 5. Some commercial products made with A. cherimola

The cherimoya is very digestive and nutritive with a particular taste as result of the harmonic combination of acids and sugars. The sugars are the product of the starch reduction. The main sugars are glucose (11.75%) and sucrose (9.4%) (Kawamata, 1977).

The principal organic acids are citric and malic acid (Bueso, 1980). For processing it is necessary to select cherimoya fruits with a high content of soluble solids and ascorbic acid (Kawamata, 1977; Vidal-Valverde et al. 1982). For immediate consumption, juicy and big sized fruits are preferred.

The aroma is one of the most distinguished characteristics of the cherimoya and related to the ripening development. The pleasant smell is the product of aromatic compounds metabolism by leucine pathway (Schreier et al, 1985 ; Lizana y Reginato,1990).

Secondary Produced Metabolites

The A. cherimola is also known as medicinal plant. Tea made from leaves and bark is relaxing. The fruit is moderately laxative and benefits the digestion (Garcia-Barriga, 1974).

The cherimoya fruit produces more or less 208 volatile compounds, 23 hydrocarbons, 58 esters, 47 carbonils, terpenoids (mono and sesquiterpens), kar-3-ene, 54 miscellaneous structures of alcohol as 1-butanol, 3-metyl-butanol, 1-hexanol, linalol and 3-metyl butyl ester (Idstein et al, 1984; Ekundayo and Oguntimein, 1986; Chen et al. 1998a, 1998b, 1998c; 1999).

Since 1970, the cherimoya was used by the natural products industry due to the high presence of secondary metabolites that show antimicrobial activity. The cherimoya leaves are rich in dimeric proantocianidines (Weinges et al, 1969). The stems are rich in alkaloids such as liriodenine, anonaine, michelalbine and (+)-reticuline (Urzua and Cassels, 1977; Chen, 1997). Simeon et al. (1989) reported 18 alcaloides (9 aporfines, 3 oxoaporfines, 1 proaporfine, 4 tetra-hydroprotoberberines and 1 bencil-tetrahydro isoquinole) from extracts of bark and stems.


18

Table 7. Food components in 100g of A. cherimola edible portion

Component

Concentration Promedium

 

 

 

Calories

62.0

kcal

Energy

265.0

kj

Water

74.1

g

Carbohydrates

13.4 - 18.2

g

Ash

0.6 - 1

g

Fat

0.1 - 0.3

g

Crude Fiber

1.5 - 2.0

g

Protein

1.5 - 1.9

g

Calcium

22.0 - 32.0

mg

Minerals

0.8

g

Iron

0.4 - 0.8

Mg

Phosphorus

30.2 - 47.0

Mg

Vitamin A

0.00 - 0.01

UI

Thiamine (B1)

0.06 - 0.11

Mg

Riboflavin (B2)

0.11 - 0.14

Mg

Niacin

0.90 - 0.15

mg

Ascorbic Acid

4.3 - 5.0

mg

Notes: The edible portion. without skin and seeds is about 60% (Stahl, 1935)
Source: Cordoba, 1967; Morton, 1987; Teubner et al, 1990;

The seeds of cherimoya are rich in glycoside esteroide (ß-sitosterol-3-glucoside), isoquinoline, azantraquinone and acetogenines all of them grouped in the category of bis-tetrahydrofuran-gamma-lactona. The azantraquinone isolate was reported as cleistofoline and the new acetogenine as laherradurineero. There are also cherimolina, dihydrocherimolina and asimicina (Rios et al.1989; Villar et al, 1982).

Natural Products Industry

The seeds and the leaves of cherimoya are very rich in essential oils and reported as insecticide. The seed juice in ethanol solution kills lice (Jaramillo, 1952). The extract of stems and bark is used as poison to kill fishes and parasites. In tropical areas the extract of seeds, stems and leaves is used as repellent against insects.

The Indians say that the cherimoya leaves could inhibit the development of tumours. Two spoons of pulverised fruit is said to be an antidote against poisoning caused by food and beverages (Garcia-Barriga, 1974).


19

Extracts of bark and stems from cherimoya are rich in alkaloids and showed antimicrobial activity against gram positive and negative bacteria (Nickell, 1959). The barks contain Annonaine (3µg/ml), which is active against Klebsiella pneumoniae, Norushinsunia (100 µ/ml) is active against Pseudomonas aaeruginosa and anolobina controls well the yeast Candida albicans.

Other alkaloids that are present in high concentration as isoboldine, corypalmine, discretamine and stepholidine were inactive against the micro-organisms tested, the experimental results showed a great effect against bacteria gram positives as Bacillus subtilis, Staphylococcus aureus and Mycobacterium phlei (Simeon et al, 1990).


20

1.3 Annona muricata L. Sp. Pl. 536, 1753

A. muricata is the most tropical semideciduous tree with the largest fruits of the Annona genus, widespread at the tropic areas of Asia, Central and South America including the Amazon basin. It is known as guanabana (Spanish), graviola (Portuguese), naqka (Austronesian), Stachelannone (German) and soursop (English) (cf. Table 1). The Spanish name „Guanábana“ is a variation of the Arawak word „Guanahaní“, who remember the first Caribean island in the Antilles, landed by Christopher Columbus in 1942 and renamed today San Salvador.

The A. muricata is regarded as great delicacy in areas where A. cherimola can not grow. In contrast with the other Annona spp., the A. muricata flowers and fruits more or less continuously during the whole year. The fruit pulp is exceptionally well suited for juice production and the vegetative parts have a medicinal application. The market of soursop is potential at the tropics and undetermined in the word season areas. The demand of soursop in 1999 does not exceed the supply in the productive countries.

1.3.1 Origin and Distribution

A. muricata is native to the Antilles. It grows well below 1,150 m SL in the most tropical micro-ecosystems of Central and South America. In Colombia there are reported more than 1,134 ha of soursop with 15 tons/ha yield

There are established A. muricata plantations in Argentina, Australia, Bahamas, Brazil, Bermudas, British Guiana, Colombia, Cuba, Curaçao, Dominican Republic, Florida (USA), French Guiana, Haiti, Hawaii, India, Jamaica, Malaysia, Mexico, Panama, Pacific Islands, Peru, San Salvador, Santo Domingo, South East China, Surinam, Philippines, Trinidad and Tobago, Venezuela and Vietnam (Figure 6) (Morton, 1987).

Figure 6. World distribution of Annona muricata


21

1.3.2 Description

A. muricata is a tropical evergreen semideciduous fruit tree (4-15 m) (Figure 7), branched near the base, with all parts evil-smelling when bruised. The branchlets are terete, finely wrinkled, scabrous, reddish brown and glabrous, with many round lenticels. The leaves are entires with an acute or cuneate base, biserate, short petioled, dark green and shiny, the upper surface is lustrous and leathery or coriaceous with a obovate, or elliptic-oblong form, shortly acuminate apex and narrow transparent margin.

The flowers are cauliflowers, regular and pedicled, strong-smelling and borne on the short, axillary, one or two flower branchlets. The pedicel is densely clothed with short hairs, the bract is small. The three sepals are almost free, dark green, ovate triangular, coriaceous, densely clothed with small hairs (Figure 7).

The six petals are placed in two rows, the three outer ones are the largest, thickly coriaceous, covered with a short tomentum, they are first green and later on pale yellow, their size is 3-5 cm long and 2-4 cm wide. The three inner petals are smaller, alternate with the outer ones, thinner, short clawed towards the base, yellowish 2-4 cm long and 1.5 - 3.5 cm wide (Figure 7).

The numerous stamens are borne in many rows on a raised torus and crowned in whorls around the ovaries. The filaments are short, thick and densely pubescent, the connective is thickened and produced beyond the linear anthers. The ovaries are numerous densely pubescents, afterwards confluent into a collective berry which bears the styles in the shape of soft reflexed prickles, while the torus develops within the fruit into a robust-uvulate carpohore.

The fruit is the largest of the Annonas spp., weighing up to 7 kg. It is a syncarpous ovoid or ellipsoid, usually irregular, oblique or curved, heart shaped. It measures between 15-35 cm length and 10-15 cm width. The skin is dark green on the immature fruit, becoming slightly yellowish green, glabrous, but bears numerous and fleshy spine-like prickles. The pulp is creamy white, fleshy, juicy and subacid with soft, cottony stands that contain many seeds. The seeds are numerous (100 approx.), glabrous with a horny testa and strongly ruminate albumen 2 cm long, obovoid, compressed, shiny with dark brown colour (Figure 6) (Morton, 1987).

1.3.3 Bloom, Harvest and Storage

Like A. cherimola the A. muricata has a dichogamous protogynous flower behaviour (cf. Figure 3). There are several floral stages of soursop during the whole year. The production of the flowers is not uniform but constantly (Moraes, 1979; Escobar and Sanchez, 1993).

The A. muricata fruit grows with a typical sigmoid pattern and matures in 100-150 days. The increment of size and weight is proportional to the number of fertilized pistils. The size of the resulting fruits ranges from 4,000- 22,000 cm³ and weight 0.8-7 kg (Bridg et al. 1994). The soursop blooming is influenced directly by the environmental conditions, self-pollination levels as low as 2% have been reported, furthermore the natural pollination by insects is occasional (Gardiazabal and Rosenberg, 1988).


22

Figure 7. Aspect of Annona muricata tree, flower and fruit and plantation

Escobar and Sanchez (1993) reported for first time the presence of Tapinoma spp.,


23

(Hymenoptera-Formicidae) ants and Ciclocephala signata (Coleoptera- Scarabacidae), Diabrotica spp., (Coleoptera-Chrysomelidae), Carpohilus spp., (Coleoptera-Nitidulidae) and Coleoptera-Staphylinidae, which are benefiting the natural pollination of soursop in Colombia. However there are no reports on the efficiency of this entomophilous pollination. Thus, artificial pollination is a widely recommended practice in productive commercial A. muricata plantations.

The A. muricata fruit is best harvested while it is still light green and has grown to its maximum size. The fruits should not ripen entirely on the tree, because they are too heavy and fall down. On the other hand unripe fruits are bitter. The soursop gains maximum yield after the sixth or seventh year of production, because the cauliflower formation is superior to the branched blooming.

The seasonal production of A. muricata in the countries where it is commercially cultivated is reported (Table 8). Yields of 10 tons/ha/year are reported in Puerto Rico, 20 tons/ha/year in Hawaii and up to 15 tons/ha/year in Colombia (Escobar and Sanchez, 1993). Furthermore, the existing actual market for A. muricata frozen pulp is open and suggests, that the potentialities of this species in the tropical fruit world trade for the next century are great.

Table 8. Seasonal production of A. muricata in several countries

1.3.4 Cultivars

A. muricata has been propagated by seeds and as the other Annona spp., its pollination problems are affecting fruit quality. In natural conditions the wide range of fruits with different shape, flavour and flesh consistency is interesting in terms of plant selection.

In 1999 there are no selected A. muricata cultivars reported, however some general classifications have been tried for the first time in Puerto Rico, considering factors such as fruit form, flavour and consistency (Table 9).


24

Table 9. Classification of soursop cultivars in Central America

Classification by

Description

 

Round

Form appearance

Heart-shaped

 

Oblong or Angular

 

 

Sweet*

Flavour pulp

Sweet-sour

 

Sour

 

 

Soft

Flesh consistency

Juicy

 

Dry

The term “sweet“ is used in a relative sense to indicate low acidity
Source: (Morton, 1987)

In other countries like El Salvador a medium-sized, yellow-green, fiberless, soursop is reported and called „guanábana sin fibra“. It has been vegetatively propagated by the Agricultural Experimental Station of Santiago de las Vegas in Cuba. This selection is one of the most productive in Central America (Morton, 1987).

In Colombia there are no still established selections of A. muricata cultivars, there the most relevant considered characteristics on the A. muricata tree are bearing growth pattern, brix grade and natural tolerance to some limiting quality diseases like Colletotrichium spp., (Escobar and Sanchez, 1993).

1.3.5 Cultural Aspects

The natural growth pattern of A. muricata is a canopy. Thus, open-globe pruning system is a desirable training method (Escobar and Sanchez, 1993). In commercial orchards training should be made and the tree size must be reduced to 2.5-3 m.

The basic framework of the tree is developed over the first three years. From then on-pruning is mainly used to maintain tree shape, restrict size, regulate cropping and rejuvenation.

In terms of productivity, the soursop countries are still developing training methods. The unique clear training definition is to open the tree and improve ventilation to reduce the attack of fungi diseases.


25

Environment

The main climatic factors that are affecting fruit production are: temperature, humidity, rainfall and wind (George, 1984). A. muricata is tropical. The tree grows well between 500 and 1,250 m SL. in areas with plenty of sun and protection against strong winds.

Temperature and humidity are the principal factors that are influencing growth and development. The A. muricata such as the other Annona spp. is not cold tolerant. Temperatures between 25-28 °C and 60-80% humidity are desirable. Trees exposed to temperatures below 12 °C drop their leaves and flowering and pollination are physiologically affected.

The fungi attack increases proportionally with the humidity and temperature, i.e., in Valle del Cauca, Colombia leaf development and fruit production are limited by the fungi Colletotrichium spp., (antracnosis) when 85% or more of ambient humidity is reported at 28-30 °C temperature (Escobar and Sanchez, 1988).

Because of its semideciduous habit the A. muricata requires active growth and vegetative development requires 800-1,000 mm3/year, in the form of well distributed rainfall .

The A. muricata grows well in acid, sandy soils, porous, oolitic and preferentially limestone soils. Desirable growth is achieved in semi-dry deep soils (1.20 m), rich in minerals and well drained. Good aeration and drainage are required in any case. The soursop does tolerate lack of water. Soils with pH from 5.5-6.5 appear to be most suitable (Table 10) (Morton, 1987).

Table 10. Ecophysiological requirements of A. muricata

Climatic Factors

Range

 

 

Elevation

500 - 1,000 m SL

Climate

tropical

Temperature

25 - 30 °C

Wind

Moderate

Humidity

60 - 70 %

Soil

Limestone

Precipitation

800 - 1,000 mm

PH

5.5 - 6.5

Limitation

Fungi susceptibility

1.3.6 Pest and Diseases

In Queensland (Australia), the principal A. muricata pest is the mealybug (Pseudococcidae spp.). The soursop is an ideal host for fruit flies like Anasptrepha suspensa, Anastrepha striata and Ceratitis capitata, Red spiders are also problem in dry climates (Morton, 1987).


26

In Colombia leaves and fruits are attacked by insects Homoptera spp., Acarina spp., Lepidoptera spp., and Coleoptera spp., all of them present during the entire biological cycle of A. muricata and only the Lepidoptera spp., are present in the most juvenil stages. The species Bephratelloides maculicollis and Cerconota annonella drill throughout the fruit causing several yield problems (Table11) (Escobar and Sanchez, 1993; Donascimiento et al. 1998). The principal disease of A. muricata is caused by the fungus Colletotrichium gloesporoides (antracnosis). The attack of this fungi is general and affects the leaves as well as fruits and flowers. Important beneficial prey aphid agents for A. muricata are Aphidius testataceipes, Chrysopa spp., and Curinus spp.

Table 11. Reported A. muricata pathogens in Colombia plantations

Organ

Pathogen

 

 

Leaves-Branches

Aconophora concolor, Aleurodicus giganteus, Aphis gossypii, Aphis spiraecola, Colapsis spp., Colletotrichium gloesporioides, Corticum salmolicolor, Corythucha ossypii, Diabrotica spp., Empoasca spp., Empocasca spp., Eriophyes Annonae, Hylesia spp., Leucoptera spp., Phylephedra spp., Sabulodes spp., Saissetia coffeae, Salenaspidus articulatos, Scolecotrichum spp., Tetranychus mexicanus, Toxoptora aurantii

Trunk-Stem

Atta spp., Colletotrichium gloesporioides, Cratosomus bombina, Nasotiternes corniger, Trachyderes interruptus.

Flower

Cercospora Annonae, Ciclocephala signata, Colletotrichium gloesporioides, Tecla ortignus, Toxoptora aurantii.

Fruit

Antiteuchus hediondus, Antiteuchus tripterus, Bephratelloides maculicollis, Cratosomus inaequalis, Cerconota annonella, Colletotrichium gloesporioides, Rhizopus stolonifer, Toxoptora aurantii.

Root

Armillaria mellea, Fomes lamaoensis, Phytophtora spp., Rhizocthonia spp.

Source: Morton (1987); Escobar and Sanchez (1993)

1.3.7 Propagation

In Colombia as well as in other tropical countries the native orchards of A. muricata are comming from old seedling plantations. The soursop is propagated by seeds, but the variation among individual trees is often great. Germination of seeds causes no major problems and takes from 15-30 days if humidity is low (approx. 60%) and temperatures above 12 °C are maintained. Pre-treatment of seeds with fungicides are required and 90% of viability is expected after 5 months (Escobar and Sanchez, 1993).

In productive orchards the selected A. muricata plants are being propagated by grafting. This propagation is a recommended practice in order to maintain clonal selections. The soursop may be either budded, shield-budded, or grafted on rootstocks of the same species. Buds should be taken from mature non-petioled wood of the previous


27

year shoot growth. Seedlings or budded plants grow rapidly and come into bearing by the third year (Morton, 1987).

Grafting soursop (A. muricata) on custard apple (A. reticulata) or mountain soursop (A. montana) has a moderate dwarfing effect, whereas grafting on pond apple (A. glabra) rootstock has a strong dwarfing effect. If grafted on sugar apple (A. squamosa) or cherimoya (A. cherimola), vitality is limited, while reduction processes at the top of the tree are reported. In Ceylon and India grafting on sugar apple (A. squamosa) is preferred (Morton, 1987).

In Colombia there are no published reports on grafting, however the graft compatibility of soursop on soursop has been studied (Escobar and Sanchez, 1993). Cutting propagation of selected types has been implemented in Colombia, but no results are reported because the A. muricata has difficulties to induce roots.

1.3.8 Properties

The wood of A. muricata tree is pale, aromatic, soft, light in weight and not durable. It has been used for ox yokes because it does not cause hair loss on the neck. In Colombia it is deemed to be suitable for pipestems and barrelstaves. The wood of soursop has a high potential to produce paper pulp. Investigations in Brazil showed a cellulose content of 65 to 76% (Morton, 1987).

A. muricata fruits may be eaten fresh, when the fruit colour has turned to green-yellow. The flesh can be eaten with a spoon and the seeds plucked. Its pulp is cotton white, very succulent and sub-acid, the flavour is acid tang “crisper“. The seeded pulp may be torn or cut into bits and added to fruit cups or salads, chilled and served as dessert with sugar and milk or cream, to prepare ice cream, nectar and juice. Those are the forms which are most preferred by the consumers (Figure 8). The unripe fruit can be eaten cooked, broiled or fried (Morton, 1987; Ijjász, 1999)

Unlike the other species A. muricata is a model fruit for processing. Its pulp does not oxidize, it maintains its pleasing aroma and flavour after frost manipulation to produce soursop pulp. In Colombia the pulp is seeded manually and some difficulties are reported (Escobar and Sanchez, 1993).

1.3.9 Nutritional Value

A. muricata fruit contain 85.5% pulp, 3.3% seeds, 8.9% skin and 2.9% of a flesh receptacle (Paull et al. 1982). The soursop taste is the result of a pleasant combination of sugars and organic acids (0.65 - 0.85%), of them, the most outstanding are malic- and citric acid in a ratio of 2:1. The concentration of soluble solids varies between 0.65-0.85 % (Table 12) (Morton, 1987; Escobar and Sanchez, 1993). The A. muricata fruit is climacteric, it ripens quickly and consequently the production of ethylene rises from 0.2-0.9 µl/kg/hour to 80-720 µl/kg/hour maximum until the sixth day. During ripening the starch hydrolyses rapidly to sucrose (16.5%), glucose (21.5%) and fructose (17%) (Paull et al. 1982; Bruinsma and Paull, 1984).


28

Figure 8. Some commercial products made with A. muricata

Table 12. Food components in 100g of edible portion of A. muricata

Component

Concentration

 

 

Calories

53.1 - 61.3

kcal

Moisture

82.8

g

Carbohydrates

14.63 - 15.63

g

Ash

0.63 - 60.0

g

Fat

0.31 - 0.97

g

Crude Fiber

0.79 - 1.63

g

Protein

1.0 - 1.22

g

Calcium

10.3 - 22.0

mg

Potassium

45.8

mg

Magnesium

23.9

mg

Sodium

23.0

mg

Iron

0.47 - 0.64

mg

Phosphorus

26.0 - 27.0

mg

Starch

1.62

 

Vitamin A

0.0 - 20.0

UI

Thiamine (B1)

0.06 - 0.11

mg

Riboflavin (B2)

0.05 - 0.07

mg

Niacin

1.28 - 22.00

mg

Ascorbic Acid

29.6

mg

Amino Acids

 

 

Tryptophan

11.0

mg

Methionine

7.0

mg

Lysine

60.0

mg

Source: Paull (1982), Morton (1987),


29

Secondary Metabolites

The soursop or “guanabana“ has been used by the natives of Central and South America as medicine. All parts of the A. muricata tree are used in natural medicine in the tropics (Asprey and Thornton, 1955).

The Indians have recorded the use of “guanabana or graviola“ and diverse properties and uses are attributed to each part of the tree: bark, leaves, roots, fruit and seeds. In popular medicine in South America, herbal preparations derived from dried leaves and roots of A. muricata are used to control diabetes, as a sedative and are used as antispasmodic. The leaves and green fruits have been identified to combat diarrhoea and used as astringents.

In the Peruvian Andes, prepared tea from leaves is used against catarrh and the crushed seeds are used to kill parasites (de Feo, 1992). In the Brazilian Amazon basin, a leaf tea is used for liver problems (Branch and da Silva, 1983). The oil of the leaves and the unripe fruit is mixed with olive oil and used externally for neuralgia, rheumatism and arthritis pain (de Almeida, 1993). In Ecuador the leaf tea is taken as an analgesic and antispasmodic.

In the Peruvian Amazon the bark roots and leaves are used for diabetes and as a sedative and antispasmodic (Vasques, 1990). Indigenous tribes in Guyana use a leaf and/or bark tea of soursop as a sedative and heart tonic (Grenand et al, 1987). Feng et al, (1962) reported that bark and leaves extracts of soursop are muscle relaxant and cardio-depressant. Activity as hypotensive, antispasmodic and vasodilator has been assessed. Roots of the tree are employed as a vermifuge and the root bark as an antidote for poisoning.

In Jamaica, Haiti and on the West Indies, the fruit and/or fruit juice is said to be diuretic and serves as remedy for haematuria and urethritis, it is used against fever, against parasites, as a lactagogue, and against diarrhoea, and the bark or leaves are used as an antispasmodic, sedative, and neuroendocrine for heart conditions, coughs, grippe, difficult childbirth, asthma, asthenia, hypertension and parasites. Pulverised immature fruits, which are very astringent are indicated as a dysentery remedy (Asprey and Thornton, 1955).

Most of the active biocompounds of A. muricata are described as monotetrahydrofurans annonaceous acetogenins (Wu et al, 1995a; Gleye, 1997a,b; 1998; Yu et al. 1998) as: amyl-caproate, amyloid, annomuricins - A, -B, -C, annomutacin, annonacin-10-one, annonacin-10-one, annonacins, annonain, anomurine, anonol, atherosperminine, beta-sitosterol, campesterol, cellobioside, citric acid, citrulline, coclaurine, coreximine, dextrose, ethanol, folacin, fructose, gaba, galactomannan, geranyl-caproate glucose, gigantetrocin A-gigantetronenina, goniothalamicin, hydrocianic acid, 2,4-cis-R-annonacin-A-one, 2,4-cis-iso-annonacin, 2,4-trans-10-R-annonacin-A-one, 2,4-trans-isoannonacin, isocitric acid, lignoceric acid, malic acid, manganese, mericyl alcohol, methanol, methyl-hexano,2-enoate, methyl-hexanoate, muricapentocin, muricatetrocins -A, -B, muricatetrocins A and B, muricatocins -A, -B, -C, muricine, muricinine, muricoreacin, myristic acid, N-p-coumaroyl tyramine, Monotetrahydrofuran acetogenin, rho-coumaric acid, paraffin, potasssium chloride, procyanidin, reticuline, scyllitol, stearic acid, stepharine, stigmasterol, sucrose, tannin, xylosyl-cellulose


30

Toxicity and Antimicrobial Activity

Several studies have demonstrated that leaf, bark, root, stem and seed extracts of soursop are antibacterial in vitro against numerous pathogens (Branch and da Silva, 1983; de Feo, 1992; Bories et al. 1991) and the bark has fungicidal properties (Lopez-Abraham, 1979).

The leaf extract showed to be active against malaria. Isoquinoline derivatives found in soursop fruit were showing anti-depressive effects in animals (Hasrat et al, 1997).

Methanolic acetogenins extracts of A. muricata and A. cherimola seeds were isolated and tested against the parasitic activity of the larvae Molinema desetae and activity inhibition has been reported (Bories et al. 1991).

The cytostatic activity of aqueous, alcoholic and ketonic extracts of A. muricata were tested on the fungi (Ascomiceto) Neurospora crassa, inhibition of growth percentages was reported (Lopez et al, 1979).

The bark of the trunk and the seeds of soursop contain certain alkaloids like “anonina“, “muricina“ and “muricinina“, which can be used to produce bio-insecticides. It produces hydrocyanic acid. The bark has been used in tanning. Leaves and bark have been used as fish poison (Aguilar et al. 1947). The seeds contain 45% of a yellow non drying oil, which is an irritant poison, while pulverised seeds are effective pesticides against lice and aphids (Morton, 1987).

The bio-activity of A. muricata leaf compounds is provided by the effect of muricatocins -A and -B, 2,4-trans-10-R-annonacin-A-one, 2,4-cis-R-annonacin-A-one and N-p-coumaroyl tyramine, which significantly enhanced cytotoxicity against the A-549 human lung tumour cell line and the MCF-7 human breast solid tumour cell lines (Wu et al, 1995b, 1995c, 1995 d).

The cancer researches are also concentrating on soursop. Several scientific studies have demonstrated the anti-cancerous properties of some phytochemical derivatives from leaves, seeds and stem, which are cytotoxic against cancer cells (Zeng et al.1996). A new mono-tetrahydrofuran ring acetogenins from A. muricata is cytotoxic against Colon Adenocarcinoma cells, in which it, reached 10.000 times the potency of Adriamycin (Doxorubicin). Chemotherapy drug for some types of cancer, manufactured by Pharmacia & Upjohn (Rieser et al, 1996).


Fußnoten:

<1>

Quechua is the language of Amerindian people of central Peru, constituting the dominant element of the Inca Empire. Today the tongue is widely spoken for approximately 4 millions of people in Peru, Bolivia, Ecuador, Colombia and Argentina.

<2>

CSIRO : Commonwealth Scientific and Industrial Research Organization, Australia


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