Detailed Guide to Wax Apple (Bell Fruit) Cultivation Techniques

Wax apple fruit tastes refreshingly sweet, with an apple-like aroma, and is a cheap and excellent summer refreshment. Wax apple is native to India, the Malay Peninsula (mostly Java), the Andaman Islands and other archipelagos, and is now widely distributed across tropical regions of the world. It has been introduced and cultivated in China for more than four hundred years. At present, it is cultivated in Taiwan, China, Hainan, Guangdong, Guangxi, Fujian and other provinces (regions). Products of superior domestic varieties fetch high market prices, are deeply welcomed by consumers, and have very good prospects for development.

I. Distribution and Characteristics of Wax Apple

In China, wax apple is mainly distributed in Taiwan, China, Hainan, Guangdong, Guangxi and Fujian and other provinces and regions; it is a major source of economic income for fruit growers in Taiwan Province, while Hainan is rich in wax apple resources, and its development has only just begun.

Wax apple prefers warmth and fears cold; its optimum growth temperature is 25-30°C. When temperatures fall below 7°C during the flowering period, flower buds and young fruit suffer cold damage and drop off. In hot and humid environments, it grows fast, sets many fruits, produces large fruit and yields high output. If the fruit development period encounters drought with no rain, the fruit is small and of poor quality. After a long drought, sudden heavy rain easily causes fruit drop and fruit cracking. Under sufficient sunlight, the fruit colors well.

Wax apple is not strict about soil requirements and can grow and fruit in all types of soil, but it grows and fruits better in fertile, loose and moist soil. Wax apple is also a dominant tree species in riparian forests.

Wax apple fruit has the effects of promoting salivation and quenching thirst, relieving fever and promoting urination, and nourishing the skin. Wax apple fruit contains 92.87% water, 0.35% protein, 5.97% carbohydrates, 0.21% ash or minerals, and 0.46% crude fiber and other nutrients, and also contains vitamin C, iron, calcium and other substances. It has a unique flavor and is cool and thirst-quenching, crisp in texture, juicy and mild in taste. If a little table salt is added and it is eaten after chilling, it is even more cool and refreshing. A single wax apple fruit weighs 14-40 g, while the Black Diamond variety reaches 120-150 g.

II. Plant Morphology and Cultivated Varieties of Wax Apple

1. Plant morphology The wax apple tree is a perennial evergreen tree with spreading branches and a round-headed canopy. Leaves are simple and opposite, long elliptic-lanceolate. The cyme is terminal or axillary, with 3-10 small milky-white flowers. The fruit is a fleshy berry, pear-shaped, bell-shaped or short club-shaped, etc., growing in clusters, and the fruit has a spongy texture. Fruit colors include milky white, pale green, pink, bright red and dark purplish red. A two-year-old wax apple has an average canopy diameter of 2.3 m and a height of 1.6 m. The optimal adjustment time for the wax apple fruiting season is from March-July to December-April. The annual number of flowering and fruiting cycles of wax apple is 1-2 times/year to 4-6 times/year.

2. Cultivated varieties In China, wax apple can be divided by fruit color into 5 types: dark red, pale red, pink, green and white. At present, the most widely cultivated and most economically valuable varieties in Taiwan Province are "Black Pearl Wax Apple" and Black Diamond Wax Apple. Hainan wax apple can be roughly divided into the following categories by fruit color: (1) Large red type: the fruit color is bright and attractive, but the fruit is small and rather sour, so its development and utilization value is not high. (2) Green-white type: the fruit is small, bland in taste, cracks heavily, and the fruit color and shape are poor, so its economic cultivation value is low. (3) White type: the fruit is medium-sized and bland, with relatively low soluble solids content, and poor fruit color and shape, so its economic cultivation value is low. (4) Green type: the fruit is medium-large and crisp, with a balanced sweet-sour taste and relatively high soluble solids content, but poor fruit color, so it can be developed to an appropriate extent. (5) Green-purple-red type: the fruit is large and fairly sweet, but the fruit shape and color are poor, so it can be developed. (6) Pink type (called Nanyang type in Taiwan): the fruit is relatively large, with attractive fruit shape and color, and fine flesh, and is worth vigorously developing.

III. Cultivation of Wax Apple

1. Choice of region and timing of cultivation (1) Region selection: choose an environment with sufficient sunlight, high temperature and humidity; choose fertile, loose and moist soil; apply more organic fertilizer to poor and thin soil. When establishing an orchard, choose a site sheltered from the wind, with slightly acidic sandy soil being most suitable; sandy loam to red loam that is slightly acidic to slightly alkaline (pH 5.5-7.8) is all suitable. Frost is taboo, and drought is feared. Conditions with a large day-night temperature difference help improve fruit quality. (2) Cultivation timing: planting can be done throughout the year (in tropical regions); it is best to plant at the beginning of the rainy season, but where irrigation is available, it is best to plant when temperatures rise.

2. Raising seedlings Because there are few seeds, air layering is generally used for propagation, and grafting and cutting propagation are also used. For air layering, choose 2-3-year-old, robustly growing branches with a diameter of 1-2 cm; branches that are too old or too tender are unsuitable. Carry it out in the high-temperature, high-humidity season from May to July; roots can form in about 30 days, and after 2-3 months they are planted out in a nursery.

Cuttings are best taken from April to August; choose plump, full, already lignified 1-2-year-old branches, cut them into 14-16 cm long segments, and insert them into a constantly moist sand bed.

For graft propagation, use seedlings with a diameter of 0.6-1 cm as rootstock, and use plump 1-2-year-old branches of superior varieties as scions; from March to May, patch budding, side grafting, cut grafting or cleft grafting can all be used.

3. Orchard establishment and planting The planting spacing is 2.5 m x 4 m, that is, 66 trees per mu; after the canopies meet, thinning is carried out. After thinning, the planting spacing is 5 m x 4 m, that is, 33 trees per mu.

Planting method: dig holes 1 m long and 1 m wide and 0.5 m deep; apply 10 kg of farmyard manure, 10 kg of chicken manure, 2.5 kg of peanut bran and 1 kg of calcium magnesium phosphate fertilizer per hole, mix evenly with topsoil and return it to the hole, so that the soil mound in the hole is 0.3 m above the ground. Plant on the soil mound. After planting, dig 0.8 m deep furrows and make raised beds, with 2 rows planted per bed.

4. Water and fertilizer management Wax apple has a high fertilizer demand. Young trees need nitrogen, phosphorus and potassium, but fertilizer should be applied frequently and lightly, especially with organic fertilizer as the main type. For fruiting trees over 5 years old, nitrogen and potassium fertilizers are important.

Fruiting trees are generally fertilized 3 times a year. From July to October, before flower bud differentiation, apply 50% of the total annual amount, plus 10 kg of organic fertilizer; from November to May of the following year, during the flowering and young fruit stages, apply 25%, but chemical nitrogen fertilizer is taboo during this period, otherwise it will affect the flavor and sweetness of the fruit; from June to July, after harvesting the fruit, apply the remaining 25%. See the previous table for annual application rates.

The orchard soil should be irrigated frequently to maintain shallow moisture, but water must not accumulate; during the rainy season, drainage should be timely.

5. Pruning and shaping For young trees, keep the trunk 40-60 cm high, select about 4 robustly growing horizontal main branches above it, and shorten upright main branches to create a round-headed canopy with evenly distributed and spreading side branches.

Fruiting trees are generally pruned 3 times a year. The first is carried out around March. The second is carried out after harvesting the main crop in July, thinning out dead branches, diseased and pest-infested branches, overly dense branches, upright water sprouts and drooping branches that touch the ground, and cutting branches inside the canopy short to about 2 cm as fruiting branches for the next crop. The third is carried out from early October to the beginning of winter, cutting off all new shoots to store sufficient nutrients for overwintering.

6. Flower and fruit thinning and fruit bagging care (1) Flower and fruit thinning Wax apple blooms heavily and sets much fruit, so flowers and fruits should be thinned in time, keeping flowers and fruits at good fruiting positions to promote fruit enlargement and improve quality. Growth inhibitors are not used for flower and fruit thinning; to avoid adverse effects on fruit and new leaves, manual thinning is generally the main method. The method is: thin out flower clusters at branch tips and retain flower clusters with 1-2 pairs of leaves on large branches; thin out upward-facing flower clusters and retain flower clusters facing the sides or downward; thin out the flowers in the middle of overly large flower clusters and retain the flowers on both sides; thin out overly densely arranged flower clusters so that there is a spacing of about 15 cm between every two flower clusters.

(2) Fruit bagging care Bagging is carried out at the young fruit stage; if fruit flies are numerous, bag immediately after flower drop. Paper bags or nylon mesh bags are generally used. Before bagging, thoroughly control diseases and pests once throughout the orchard; generally wait until the pesticide on the fruit surface is dry before bagging.

IV. Prevention and Control of Diseases and Pests

The main diseases of wax apple include anthracnose, fruit rot and phytophthora blight, etc.; the main pests include tussock moths, scale insects, scarab beetles, aphids, mirid bugs and thrips, etc. Generally, agricultural control is the main method, supplemented by chemical control.

V. Harvesting, Fresh-keeping, Storage and Transport

(1) Harvesting The fruit can be harvested when it reaches the size it should have for the variety, shows the color inherent to the variety, and the fruit navel has opened. Generally, harvest once every 2-3 days. Because its peel is thin, handle it carefully and gently during harvest.

(2) Fresh-keeping and storage and transport Wax apple does not keep well; generally it can be stored for about one week at room temperature. For immediate @#@136@#@, it can be wrapped in white paper, stacked in layers in a cardboard box and packed for transport; fruit to be stored can be placed in a plastic bag or a fresh-keeping box and then kept at a temperature of 12-15°C. The fruit does not need to be washed before storage; wash it just before eating. Chilled fruit tastes even better.

VI. Fruit Processing

Wax apple fruit is generally mainly eaten fresh; adding a little table salt when eating can enhance the flavor. It can also be salted or sugared, made into candied fruit, used as a cooking seasoning, etc., and can also be made into jam, juice, etc.