Everything you need to know about growing custard apple plant! Learn about: 1. Botany of Custard Apple Plant 2. Origin of Custard Apple 3. Climate and Soil 4. Orchard Cultural Practices 5. Propagation and Rootstocks 6. Planting Operation 7. Flowering and Fruiting 8. Training and Pruning 9. Harvesting and Handling.
Botany of Custard Apple Plant:
The custard apple belongs to family Annonaceae and genus Annona. In India, the custard apple is Annona squamosa, in USA Annona reticulata or Annona glabra and in Australia Annona atemoya. About 50 species of shrubs and trees belong to this genus bearing aggregate fleshy fruit but only six species produce fruits of commercial importance.
A brief description of the Annona species is as follows:
i. Annona Squamosa- Custard Apple, Sugar Apple, Sweet Sop or Ate, Sharifa (Northern India), Sitaphal (Southern Part):
It is the most widely cultivated species in India and probably in the tropics of the world. It is a deciduous, tall, woody shrub or small tree, 5-6 m in height with irregular spreading branches. The alternate double-ranked leaves are lanceolate and acuminate. The greenish yellow flowers arise at an extra axillary position, usually in clusters and rarely solitary. Petals are in two whorls.
The outer petals are thick, linear and rounded at the apex, while inner petals are minute, ovate or abovate and keeled on the outside. The flower has numerous stamens and carpels. The fruit is composed of cohering carpels forming a tuberculated surface. The black seeds are surrounded by white creamy or custard-like pulp which is very sweet and pleasantly flavoured.
ii. Annona Cherimola- (Cherimola or Cherimoya):
It is considered best fruit among the annonaceous fruit because of its sweet flavour, buttery consistency of pulp and low seed content. It is considered one of the finest sub-tropical fruits in Brazil, Australia, Hawaii, Mexico, California and India. It has been established well in Telangana region of Andhra Pradesh.
It is a deciduous, small spreading tree with greyish pubescent shoots. The lower surface of leaf is velvety tomentum. The flowers are usually solitary with narrow outer petals. The inner petals are small and scale like. The fruits are 8 to 15 cm in diameter, green in colour and round to heart-shaped.
Baily has recognised the following five cultivars on the basis of fruit form are – finger-printed cherimoya, smooth cherimoya, tuberculate cherimoya, mammiliate cherimoya and umbonate cherimoya.
iii. Annona Reticulata- (Bullock’s-Heart, Bull’s-Heart or Ramphal):
It is essentially a tropical fruit require mild climate and thrive well all over South India upto an elevation of 1200 MSL. It is a deciduous tree, 6-8 m in height with lenceloate, long, acuminate and glabrous leaves. The exterior petals are yellowish, fleshy while the interior ones are scale-like. The fruits are smooth, heart-shaped and contain few seeds. Due to low sugar content, the fruit is inferior in quality than custard apple and Cherimoya. It comes into the market late than custard apple because flowering occurs from August to October and the fruit ripen in April and May. This species is not cultivated on commercial scale in India.
iv. Annona Muricata- (Soursop):
It is an evergreen small tree flourishing in tropical climate of central America and Peru. The fruit is also popular in Cuba and Sri Lanka. In Andhra Pradesh and Assam, it is grown on very limited scale. The leaves are short, obovate – oblong to elliptic and shinning above. The exterior petals are fleshy and valvate and interior ones are small and imbricate. The fruits are heart-shaped, extra-large with many soft spines pointing towards apex. The white, juicy pulp has acidic mango like flavour which is strained and used in preparing drinks, ice-cream, jelly and other preserves. The acid content is 3-4 times more than custard apple.
It is incompatible with custard apple and cherimoya. The low productivity in soursop has been attributed to the inadequate pollination.
Origin of Custard Apple:
In the genus Annona of family Annonaceae, five fruits are considered edible. Four of these are called the custard apple in different countries. In India only the sweet sop or sugar apple, Anona squamosa, is called the custard apple. It is the most important among these fruits in India, and is called sitaphal or sharifa in the vernacular. Another species common in India is bullock’s heart, A. reticulata, locally called Ramphal.
The sour sop A. muricata is also found in some places. The pond apple or alligator pear, A. glabra (A. palustris), is found among the plant collections of some gardens. These fruits grow semi-wild in large numbers in forests in Hyderabad area (about 40,000 hectares), in Tamil Nadu, Assam and to some extent in U.P.
It may be hard to believe, but in spite of its widespread adaptation in India since a very long time, the custard apple is an introduced fruit in India. All of these fruits have made themselves at home in India and the different members have been named after Ram, Sita, Hanuman and Lakshman.
In spite of this intimate connection with the story of the Ramayana, all members of the genus Annona undoubtedly originated in tropical America. There seems to be some doubt about the time of their arrival in India. When the Portuguese came to India, they brought these fruits with them. However, it is likely that at least A. squamosa (sitaphal) was already present in India.
This fruit was mentioned in the Ain-e-Akbari, the biography of Emperor Akbar, written only about 100 years after the discovery of America. It is seen in the old paintings at Ajanta, in the sculptures at Mathura and the Bharut sculptures.
It seems that this fruit spread from tropical America from both its coasts long before the discovery of America and had possibly reached India before the Portuguese landed here. It will be hard to convince many people in India that custard apple and guava are not indigenous to this country, but that is the truth.
These tropical fruits prefer a dry climate, can withstand mild frost, but their fruits become hard and do not ripen in cold weather. They are evergreen, but when grown in North India they shed their leaves in the cold weather. They do not like hot dry winds at the time of flowering in late spring, and consequently they do not set fruit in spring in North India, but readily do so when the rainy season starts.
Their roots are shallow and they do not require a deep soil. However, the soil should be well drained. They thrive on light soils, but can also grow in heavy soils. They can stand high amounts of lime found in calcareous soils. They are often found growing on rocky soils. The soil is, therefore, not very important for these fruits.
Climate and Soil Required for Growing Custard Apple:
Annonas are of tropical origin, prefer warm climate and moderate winter and humidity. The tree remains dormant for a short period during cold season. The prolonged cool weather and frost adversely affect its growth. The temperature above 40°C cause heavy flower drop in northern India and high temperature further affect the fruit growth and yield due to soil moisture stress. Tropical climate might not be conducive for higher fruit production. Hence, warm subtropical conditions show better fruit growth and yields.
They can thrive well up to an elevation of 1000 metres above sea level. Annual rainfall of 50-75 cm is considered adequate for its growth and fruiting. Annonas can also tolerate adverse weather conditions at the cost of growth and yield. In northern India during summer season due to high temperature and lack of humidity, no fruit set inspite of profuse flowering. Warm temperature with high humidity and occasional rains are required for good set and development of custard apple fruits. Cherimoya performs better at lower temperature than custard apple and atemoya.
Annonas can grow successfully in wide variety of soil ranging from heavy soils to almost sand. The waste lands, marginal, sandy and rocky soils can be considered for growing these fruits. However, for getting better crop, a fertile, well drained sandy loam soil and neutral in reaction is preferred. Waterlogged, heavy soils with poor drainage, sub-soil with hardpan or having high water table needs to be avoided. The custard apple is generally planted in sandy soils with limited nutrients. The growth remains stunted and yield poorly if moisture deficiencies are not compensated by frequent irrigations. These fruits do not thrive well in saline and alkaline soils.
Orchard Cultural Practices for Growing Custard Apples:
i. Irrigation:
The fruit set and development of Annonas occur during the rainy season, thus, they produce a fair crop even without any irrigation. Therefore, Annonas are considered drought- tolerant plants. It has been observed that the custard apple growing in damp and shady situation and receiving irrigation resulted in no fruit drop. The fruit also ripened about two months earlier than usual.
In atemoya, reduced flowering and fruit set has been reported at high temperature due to soil moisture stress. Under such conditions, productivity of cherimoya can be improved by cultural techniques viz, overhead misting, windbreaks and efficient irrigation scheduling.
Two to three irrigations before the onset of monsoon to promote fruit set and one to two irrigations after the monsoon to increase fruit size should be given to custard apples.
ii. Intercropping:
During the pre-bearing period, the intercrops can be grown judiciously to compensate the economic loss. Groundnut, linseed and minor millets can be given in the rainy season and pea, oilseeds and gram in the winter season. Intercrops prove beneficial in checking the soil erosion and weed growth.
iii. Manuring and Fertilization:
The custard apple is mostly cultivated on poor soils, thus, manures and fertilizers should be applied for better growth and yields. The flowering can be advanced by 10 to 15 days with high doses of nitrogen and phosphorus, but low nitrogen delayed flowering by over two months. High nitrogen rates resulted higher flower production while high N, P and K enhanced the fruit set.
The fertilizer dose for young plant has been recommended as 250 g N, 125 g P2O5 and 125 g K2O per plant. The fertilizers should be applied on the commencement of rainy season. In another trial NPK each @ 240 g per tree resulted higher yield.
Propagation and Rootstocks of Custard Apples:
Both sexual and asexual methods are employed for propagating the annona plants. However, to maintain the genetic uniformity for obtaining higher yield of better quality fruits, the clonal propagation is a must. The seedlings of local custard apple and Ramphal are good for raising rootstock for improved varieties and hybrids.
Raising of Seedlings:
In custard apple seeds very little or no dormancy is observed. The fresh seed germinate in 20-30 days and gives 90 per cent germination. The seed of custard apple do not require any seed treatment like scarification or soaking in hot water. But, soaking of Cherimoya seeds in 500 ppm gibberellic acid improved germination considerably. Seed is sown in beds or polythene bags. The plants raised in polythene bags are preferred because of ease and low mortality during transplanting.
Custard apple as a scion on seedlings of custard apple and Ramphal starts yielding in the 5th year and yields 41 fruits per plant on Ramphal and 29 fruits on custard apple. In another study it has been reported that custard apple on Ramphal shows better tree vigour and fruit quality than on custard apple rootstock. Ramphal as a rootstock also imparted longer life to custard apple as compared to custard apple on custard apple. The atemoya cv. African Pride gave about double the fruit yield on Cherimoya than on custard apple rootstock in the 6th year of planting. The seedling rootstocks, however, exhibit wide variability in growth and yield of the scion.
Vegetative Propagation:
i. Budding and Grafting:
These are the commercial methods of vegetative propagation of annonas. Among the budding methods, shield, patch, modified forkert and chip can be employed with 53 to 100 per cent success. Budding is done in early spring when the sap starts flowing or in the autumn. For taking bud wood, dormant last year’s shoots should be preferred. The grafting methods like tongue, cleft, veneer, inarching, and splice were found successful in annonas.
These methods should be carried out in early spring using one year old mature scion and more than one year old rootstock.
ii. Stooling:
The stool of custard apple after treating with 20000 ppm 1BA yields is 94 per cent success. The rooted stools gave 80 per cent survival on planting. In the month of April, head back 3 years old seedlings at the ground level. After about 3 months, a 3 cm wide ring of bark is taken out from the base of each emerged shoot leaving one to serve as a nurse shoot. Lanolin paste containing IBA is smeared above the ringed portion followed by mounding of all the shoots. The rooted shoots are detached from the mother plant in the month of September. Stooling appears to be very promising method for clonal propagation.
iii. Cuttings:
The cultivar African Pride had higher rooting potential from stem cuttings. Etiolation of shoots also improved the rooting. The cuttings of custard apple placed under intermittent mist by etiolating for 15 days and treating with 5000 ppm Naphthalene acetic acid gives 90 per cent success. Higher success from stem cuttings has also been reported in Cherimoya and Annona hybrids.
Planting Operation for Custard Apples:
It is important that grafted plants should be grown for commercial cultivation. The plants raised in nursery beds from seeds suffer heavy mortality due to damage of roots during lifting and transplanting. It is desirable that the seedlings be raised in polythene bags and after budding or grafting they should be transplanted in the orchard.
The pits of 60 cm x 60 cm x 60 cm should be dug out and filled with a mixture of soil, 20 kg well rotten farmyard manure and 300 g fertilizer mixture of urea, superphosphate and muriate of potash in equal proportion. The distance should be kept 5 m from plant to plant and row to row in square system which thus accommodates 390 plants per hectare. Custard apple can also be planted at the distance of 4m x 4m and 6m x 6m. The planting should be done during the rainy season.
Flowering and Fruiting:
Custard apple has a short juvenile phase. The plants begin flowering within 4 years of planting. Annona species bear flowers on the current season’s growth and very rarely on older wood. The flowering period of custard apples is very long commencing from March-April, continuing up to July-August. The peak flowering is observed in April and May. From initiation, a floral bud develops into flower in 27 to 35 days depending on the species.
No fruit set occurs during the entire spring and summer and it commences only in the rainy season, leaving little period for the late set fruits to develop before the onset of winter season. The setting of fruits early in the season is important because immature fruits instead of developing become inedible in winter season and turn into stone fruits.
Annona fruits usually mature in about four months from the time of flowering. The period is reduced when the soil moisture is optimum. Fruits of Ramphal mature in about six months.
The main constraint in expanding the commercial cultivation of annona fruits is due to their low productivity. Enough flowers are borne on a custard apple plant but the poor fruit set causes low yield. Under natural conditions only 1-8 per cent fruit set has been reported. The low fruit set in custard apple is due to poor pollination which has been attributed to both the external and internal factors such as very high and low humidity prevailing at the time of flowering, soil moisture stress, competition between vegetative and floral growth, hypogyny, dichogamy, poor pollen germination and dearth of insect pollinators.
The peak flowering period of custard apple in northern India coincides with the summer season when the temperature goes beyond 40°C, humidity is extremely low, desiccating wind is prevalent and the soil is in dry condition. Neither the pollen is produced nor does fruit set occur in this situation. The pollen grains shrivelles and gets sterile in May and June due to high temperature and low humidity. The fruit set occurs only in rainy season on reversal of environmental conditions.
Poor pollen grain germination has been reported in all the species of Annona. The compound nature of pollen grains, thick exine and absence of germ-pores are held responsible. In custard apple 85 per cent fruit set was noted by hand pollination in comparison with 30 per cent of the control.
NAA at 10 – 20 pm spray prior to flowering period reduce the flower and fruit drop in custard apples. Dipping of freshly opened flowers of Mammoth cultivar in 50 ppm GA3 gave 70 per cent fruit set and the developed fruits had more weight but less number of seeds. In custard apple about 18 per cent fruit set is observed by spraying the flowers with 100 ppm GA3 and NOA.
Training and Pruning of Custard Apples:
The custard apple is very slow growing plant. It forms a small bush with a large number of branches of various sizes and ages. The fruits are borne on old wood as well as new wood. Light pruning of old wood induces better branching of the plant. Pruning can best be done to avoid overcrowding and to promote well-spaced branches. In budded plants, the growth is uniform and there is very little need for any pruning.
The custard apple normally goes to dormancy from November to December. The leaves gradually turn yellow at the time of harvest of fruit and drop with the approach of winter. The plants remain in leafless condition for about two months in the winter season and new growth emerges with the onset of spring. Pruning should be carried out when the plant is to put forth new growth in early spring after dormancy.
The completion of leaf fall is essential for the initiation of new growth in annonas. Two sprays of 0.5 per cent potassium iodide at weekly interval resulted in not only early and prolonged harvest but also gave higher yield. In the custard apple cultivar Balangar, manually and chemically defoliated plants and the control produced 17.4, 24.4 and 13.0 kg fruit per plant respectively. In the cultivar Red Sitaphal and Mammoth, manual defoliation was, however, better than chemical treatment.
Harvesting and Handling of Custard Apples:
The custard apple is plucked from the tree while still firm and plumpy. When allowed to remain on the tree, the fruits get damaged due to splitting instead of ripening properly. On the other hand, immature fruits after harvest become soft and rot, though the skin remains intact. It is, therefore, essential to harvest the custard apples at the proper stage of maturity. The custard apple is a climacteric fruit. The fruits of custard apple or sugar apple should be picked when they have attained light green colour.
There should be yellowish white colour between the carpels and initiation of cracking of the skin between the carpels. The individual fruit needs to be examined every alternate day to judge the stage of maturity for harvesting. The fruits are hand-picked. The fruits in the coastal regions ripen earlier. The harvesting of custard apple starts from August and continues upto December, the peak period being October- November. The cherimoya fruits reach the market after custard apple followed by those of Ramphal.
Annonas plants begin bearing at the age of 5 year. The productive life of these trees is approximately 15 years. The 8 year old seedlings yield average number of 149 fruits per plant. The custard apple tree usually produces about 80-100 fruits each weighing 150-300 g. The atemoya cv. African Pride gave 18.7 tonnes yield of marketable fruits per hectare on cherimoya rootstock and 9.2 tonnes on custard apple rootstock in the 6th year of planting.
The custard apples ripen within few days after harvest. In an experiment, when the custard apples fruits were placed in straw, fruit leaves and open baskets; they ripened in 4, 5 and 6 days respectively. The longest shelf-life of four days at room temperature was found in fruits ripened in straw and fruit leaves. The custard apple fruits ripen normally at 15-30°C in storage. Low relative humidity accelerates the process of ripening.
The fruits wrapped in perforated polyethylene bags and ripened in wheat straw suffered the least diameter loss compared with wrapping in paper bags and ripening in sawdust or gunny bags. The ripe fruits being soft and perishable require careful handling in marketing. The fruits should be wrapped in a piece of strong paper and allowed sufficient ventilation in packing when the fruits are to be sent to the distant markets.
The fruits of custard apple could be kept for about a week after treating with 8 per cent wax emulsion in combination with 400 ppm 2, 4-D and 2, 4, 5-T. Cherimoya fruits can be stored for 12 days at 9°C and 85-90% RH and 2% oxygen plus 10% carbon dioxide in controlled atmosphere storage. The shelf life of custard apple fruits can be extended upto 6 days at ambient temperature and 9 days in zero energy cool chambers after wrapping in tissue paper and placed in cardboard boxes.