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Introduction

Annona is a genus of family Annonaceae,  Annona species are tropical trees taprooted, evergreen or semideciduous, Annona considered the largest one of five species of family Annonaceae  containing 66 species approximately.

Annona species are native to tropical region like tropical America, eastern Africa , subtropical or tropical highland conditions; like East Africa and Asia,  also, few species found in temperate regions. Nowadays it is cultivated in almost all Arabian region like Egypt, Lebanon, Sudan, K.S.A., Oman, Jordan and Palestine.

Botanical description

Annona sp.  are shrubs or small trees, Annona  are deciduous,  or semi deciduous even tropical species, especially when cultivated in areas with dry or cool seasons. Leaves  5 to 12 cm long,  simple which are ovate-lanceolate to elliptical in shape, glabrous on the ventral surface, Annona flowers are fragrant flower emerges from the leaf axils, and possesses a short peduncle, 2.5 cm in length, solitary or in fascicles with 2 to 4 flowers, The fruit is normally heart-shaped, conical, oval or somewhat irregular in form due to irregular pollination. The fruit surface is covered with small conical protuberances over the carpel. The fruit rind is delicate and thin, and is greenish-yellow when ripe. The white, flesh has a fragrant, delicate flavor. The fruit has numerous seeds (21 to 41 seeds/fruit), which are black and small size, all old leaves dropped one shoot before new buds opening.

Soil

All Annona species can grow in a wide range of soil types, from sandy soils to clay loams. However, produce better in fertile, well deep and well-drained soils,, rich in organic matter. No Annona grows well in soils with drainage problems (Heavy clay soil), high water content in the soil causes root diseases. The best physical/chemical composition for Annona cultivation was pH 6.5 to 8.5, with an organic matter content of 6.2%, nitrogen of 0.25%, phosphorus of 2.8 ppm, and potassium of 0.79 meq/100 g, generally prefers deep soils with good aeration.

Transplanting and spacing

 Current field spacing ranges among commercial orchards, from  3.5 x 5 m in sandy soil to 5 x 7 m in clay soil

Flowering

Annona  trees start flowering when the plant is three to four years, the flowering stalks rise from axils, or occasionally from axillary buds on main stems  or older stems, flowers are  hermaphrodite; both female ( carpels ) and male (stamens) organs are in the same flower. However,  Anthesis  starts slowly, with the separation of the apex of  the external petals and takes from 6 to 8 h to complete the female part matures before the male, which is known as dichogamy of the protogynous type.

 Productivity  and Harvesting

Fruit maturation within 5to 8 months, hence, each tree must be inspected regularly to collect the fruits at the appropriate harvest point. The most suitable time of day to harvest is in the morning just after the evaporation of the dew, when the fruits are dry and fungal rot contamination is less likely

Annona tree production has an average yield of 35 kg during the normal harvest period, depend on hand pollination,  soil fertility and climate conditions. Annona  sp. are harvested from June  to the end of October in Egypt, Hand pollination is the only certain strategy to ensure commercial production

Fruit thinning is necessary to regulate crop load and to maintain fruit size, especially for high yielding Annona cultivars.

Annona fruits must be hand-harvested and put into cushioned boxes or baskets to avoid mechanical damage or bruising.

Nutritional value of Annona fruits

In general, Annonas are consumed as fresh fruits, but they are also widely used in semi-processed and processed products, especially desserts. As world demand for exotic flavours and healthy foods expands, the use of Annona fruits is also likely to expand. Annona pulps are rich source of Vitamin A, B and C , proteins, fatty acids, fiber, carbohydrates and minerals  comparing with other fruits. Annona give the consumer a glowing and healthy skin and shiny and lustrous hair,  each 100 g flushes contain 1.1 g protein, 0.3 g fat-21.5 grams carbohydrate is dissolved sugars (sucrose, sugar reducers 12.8% 7.2%), 0.5 g fiber,  the high amount of magnesium in Annona fruits maintains water balance in the body.

Annona against  Cancer

Currently the Annonaceae remain a “hot’ family for the discovery of new anti-cancer drugs,  Annona contains a class of chemicals called acetogenins, which to be 300 times more potent than  standard anti-cancer drug .

        Limiting factors  for Annona production in Egypt

  Dry wind during flowering period

 Dichogamy 

3-The pollinating insects are rare, a small population of pollinator insects may limit fruit set. Consequently, there is often very low fruit set from natural pollination, varying from 0% in some orchards to 26% in some orchards.

The use of hand pollination  necessary to increase fruit set, since it guarantees significantly higher production and better fruit quality than open pollination.

Types of Annonas in Egypt

Main Annona types cultivated in Egypt

 A.cherimolia. Cherimoya

 A.reticulata. Bullock sheart

 A.atemoya.