Table of Contents
Introduction to Custard Apple (Annona squamosa L.)
Origin and Distribution
- Custard Apple is native to the West Indies and South America
- Introduced to other parts of the world, including India, by the Portuguese
- Custard Apple is widely cultivated in tropical and subtropical regions globally
Names and Nomenclature
- Common names: Sugar apple, sweetsop, noi-na, sharifa, sitaphal, ‘ata’, ‘attichaka’, ‘atakatal’
- Believed to be of Indian origin due to Sanskrit names, mentions in historical texts, and appearances in ancient art and carvings
Composition and Uses
- Edible portion: Pulp (45%), peel, and seeds
- Pulp: Cream-colored, custard-like, granular, sweet, pleasant flavor, and mild aroma
- Nutritional composition per 100g: 70.5g moisture, 23.5g carbohydrates, 1.6g protein, 0.4g fat, 17mg calcium, 47mg phosphorus, 1.5mg iron, 0.07mg thiamin, 0.17mg riboflavin, 1.3mg niacin, 37mg vitamin C, and 104 kcal energy
- Uses of custard apple: Fresh consumption, ice creams, puddings, jams, jellies, squash, syrup, nectar, canned products, and fermented alcoholic beverages
- Medicinal properties: Fruits, seeds, leaves, and roots are valued in Ayurvedic and Unani systems
Botany and Varieties
Botanical Classification
- Family: Annonaceae
- Genus: Annona
- Species: Annona squamosa
Botanical Description
- Medium-sized, semi-deciduous, woody tree
- Leaves: Lanceolate and acuminate
- Flowers: Greenish-yellow, six petals in two whorls, numerous stamens and carpels
- Fruits: Syncarpous, medium-sized, globular, green reticulated skin, creamy white sweet pulp in distinct segments surrounding seeds
Varieties
- Grouped based on external fruit color: Green, red, and yellow custard apples
- Common varieties:
- Balanagar: Green-skinned, medium-sized fruits, high-yielding
- British Guinea: Good pulp and sugar content
- Barbados seedling: High total soluble solids (TSS)
- Mammoth: Good pulp content and TSS
- Washington PI 98797: Good fruit weight, pulp, and TSS
- Red Sitaphal: Dark pinkish fruits, more seeds
- Israeli Selection and Israeli Hybrid: Natural hybrids with fewer seeds
- APK (Ca)1: Released by Tamil Nadu, medium-sized, heart-shaped, good TSS
- Arka Sahan: Hybrid, suitable for drought-prone areas, high TSS, few seeds, long shelf life
Climate and Soil Requirements
Botanical Classification of custard apple
- Adapted to tropical climates
- Prefers moderate winter and high humidity during flowering for better fruit set
- Cannot withstand frost and prolonged cold weather
- Continuous rains during flowering and fruit set result in poor yields
- Optimum rainfall requirement: 60-80 cm
- Strong winds can cause limb damage, flower drop, and fruit damage
Botanical Description
- Custard apple grows on a wide variety of soils, including sandy, marginal, and wastelands
- Fertile, well-drained sandy loam soils with neutral to slightly acidic pH are ideal
- Heavy soils and waterlogged conditions are not suitable
- Prolonged water stagnation should be avoided
Propagation
Seed Propagation
- Widely followed, resulting in high natural variability
- Seeds extracted from ripe fruits
- Seed viability lasts 3-4 years, but fresh seeds give the best germination
- Seed treatments like soaking in cold water or GA3 improve germination by softening hard seed coats
Vegetative Propagation
- Preferred for commercial multiplication to maintain true-to-type plants
- Cuttings and layering are not successful
- Grafting is the best method, giving the highest success and field establishment
- Patch, shield, chip, and veneer grafting are successful
- In-situ cleft grafting is suitable for drought-prone/rainfed areas
Tissue Culture
- Multiple shoot production from leaf explants
- Root initiation from unproductive seedling trees
- Bark grafting of inferior quality seedlings
Cultivation Practices of Custard Apple
Planting
- Square or triangular planting system
- Planting in pre-prepared pits (50-60 cm3) with topsoil and 25-30 kg farmyard manure
- Recommended spacing: 4-5 m, accommodating 625-400 plants/ha
- Closer spacing is advantageous for improved pollination and fruit set
- Planting during monsoon (June-July) or in February with irrigation
- Shading, staking, and watering after planting in the main field
Manures and Fertilizers
- Custard apples respond well to fertilizer application for increased vigor, production, and quality
- Increased N, P, and K levels result in increased total sugar content of fruits
- Fertilizer doses vary by region, but application should coincide with rapid vegetative growth and fruit development stages
- Nutrient requirements can be determined based on tissue analysis results
- Deficiency symptoms: Restricted growth and pale yellow leaves (N), reduced growth, necrotic bands at leaf tips and margins (P), marginal scorching of leaves (K)
Training and Pruning
- Training is intended to build a good framework and crown
- Pruning removes dead, misshapen, and very old branches
- Periodic pruning prevents bushiness and maintains bearing efficiency
- Artificial leaf removal can be practiced to induce new growth using chemical defoliants like potassium iodine spray(0.5%) or ethrel (1000 ppm) in increasing flowering and fruit yield
Irrigation
- Custard apples respond well to fertilizer application for increased vigor, production, and quality
- Increased N, P, and K levels result in increased total sugar content of fruits
- Fertilizer doses vary by region, but application should coincide with rapid vegetative growth and fruit development stages
- Nutrient requirements can be determined based on tissue analysis results
- Deficiency symptoms: Restricted growth and pale yellow leaves (N), reduced growth, necrotic bands at leaf tips and margins (P), marginal scorching of leaves (K)
Flowering and Fruit Set
- Bearing starts by 3-4 years
- Hermaphrodite flowers produced singly or in clusters on current season’s growth
- Flowering period: March-April to July-August, peak in April-May
- Very low natural fruit set (1-8%) due to poor pollination and dichogamy
- Hand pollination increases fruit set, fruit size, and early harvesting
- Growth regulators like GA3 (50 ppm) at blooming stage improve fruit set
- Leaf stripping (5-10 terminal leaves) increases late flowering and fruit set
- Excessive vegetative growth reduces fruit set
- Uniconazole (growth retardant) reduces shoot extension and increases flowering
- NAA (10-20 ppm) before flowering reduces flowering and fruit drop
- Sap beetle pheromones and food odor baits attract beetles, increasing pollination and fruit set
Harvesting and Yield of Custard Apple
- Fruits mature 100-200 days after anthesis
- Climacteric fruit, should be harvested at matured stage
- Maturity indices: Light green color, yellowish-white color between tubercles, initiation of skin cracking between carpels
- Fruits are picked individually when fully mature but still firm
- Deformed fruits due to presence of unfertilized carpels
- Average yield: 100-150 fruits per tree
- Productivity life: Up to 25 years
Post-Harvest Management
Ripening and Storage
- Custard apple fruits ripe in about three days
- Before ripening, pulp is not separated into segments or flakes
- When ripe, fruits are very fragile and disintegrate into segments with slight pressure, so careful handling is required
- Ripe fruits can be stored only for 2-3 days without decay
- Dipping in Bavistin (500 ppm) followed by keeping in polythene bags with KMnO4 increases storage life to 9-10 days
- For distant markets, fruits are stored under cold conditions (10-15°C, 3-5% oxygen, and 5-10% carbon dioxide concentration)
Processing Constraints
- Extraction of pulp is a major constraint in processing custard apple fruits
- Development of bitterness and unpleasant off-flavor in the pulp on heating beyond 65°C
- Presence of gritty cells
- Cold pressing is employed for extraction of fruit pulp
- A centrifugal process is developed to separate gritty portion from pulp
Crop Protection
Physiological Disorders
Stone Fruit:
After the harvesting season, plants enter dormancy during winter, followed by new flushing in spring. Neglected trees and plants under moisture and nutritional stress enter dormancy well before all fruits are harvested. Remaining fruits turn brown, become hard, and further development ceases, leading to their retention on trees for a prolonged time.
Mummified Fruits:
Sometimes, very young fruits turn black, become hard, and further development is stopped, resulting in mummified fruits, considered a natural thinning mechanism under stress conditions.
Woodiness and Brown Pulp:
‘Woodiness’ is characterized by the presence of woody seed pockets and gritty lumps in the flesh, while ‘brown pulp’ indicates discoloration of the pulp. These disorders can be improved by using dwarfing inter-stocks of A. squamosa or dwarfing rootstocks of A. cherimola and maintaining adequate calcium concentration in leaves and fruits.
Pests
- Mealy bug (Planococcus pacificus) damages young shoots and fruit segments, causing blemished fruits and reducing market demand
- Control with sprays of phosphamidon (0.05%) or dichlorvos
Diseases
Fruit rot:
- Caused by Phytophthora citrophthora and P. nicotianae
- Infected fruits develop purplish or brownish-black discoloration, followed by browning of interior tissue, leading to complete blackening and mummification within a week
- Protection with sprays of ridomil (Metalaxyl-MZWP) at 2.5g/L or ridomil-cupriant WP at 1g/L, but inhibition after infection is not achieved by any chemicals
Leaf spot:
- Caused by Alternaria sp.
- Appears during the end of harvesting in November, leading to considerable crop loss
- Severe leaf fall is the major symptom
- Varieties like Red Sitaphal, Island Gem, and British Guinea are moderately susceptible, no resistant or tolerant cultivars reported
- Control with sprays of benlate (0.05%), bavistin (0.05%), or baycor (0.1%) at fortnightly intervals
Anthracnose:
- Caused by Colletotrichum gloeosporioides (Glomerella cingulata)
- Control with the same sprays as for leaf spot
