Everything you need to know about growing aonla! Learn about: 1. Botany of Aonla 2. Origin of Aonla 3. Climate and Soil 4. Orchard Cultural Practices 5. Propagation Techniques 6. Flowering and Fruiting 7. Harvesting and Handling 8. Varieties.
Botany of Aonla:
Aonla belongs to genus Emblica and family Euphorbiaceae.
i. Emblica Officinalis:
The tree is evergreen in the tropical climate but is deciduous under sub-tropical conditions. The tree is spreading in nature and attains height of 10-20 metres in different types of soil.
ii. Emblica Myrobalan:
It is a small sized deciduous tree. The fruits are 1.5 – 4.0 cm in size and are used for preparation of various products.
iii. Emblica Fischeri:
It is a small tree with large leaves. Its fruit is used for making pickle and chutney.
Earlier, aonla was categorised under genus Phyllanthus which comprises of about 500 species. Emblica officinalis is a monoecious plant having male and female flowers separately on the same panicle. Male flowers appear in clusters and bear in very high proportion. Female flowers have tiny green parianth and number of segments varies from 5 to 6 or even upto 7.
These flowers bear on upper end of few branches. Fruit is capsular berry (drupaceous) with fleshy exocarp. Edible portion of the fruit is epicarp and mesocarp. The endocarp forms the hard stone which encages the seed. Seeds are 6-8 tightly embedded in the centre. The seed coat is dark chestnut brown and hard.
Origin of Aonla:
The Indian gooseberry, ‘aonla’ or ‘nelli’ is sometimes called myrobalan, is a name also used for some other fruits. Botanically, it is called Phyllanthus emblica or Emblica officinalis and it belongs to the family Euphorbiaceae. The small leaves are clustered on their branchlets in such a way that each branchlet appears to be a compound leaf.
Male and female flowers appear on these branchlets late in spring, when hot winds blow in North India and fruit-set is often a problem. Sometimes the trees set no fruit for many years. Some trees continue to bear a scanty crop throughout their life.
Aonla is said to be indigenous to tropical south-east Asia, particularly Central and South India. It is commercially cultivated in U.P. and can be seen in Gujarat, Maharashtra and West Bengal. It also grows wild at the foot of the Himalayas and at elevations upto 1500 metres in South India.
Aonla is a cross pollinated plant. Wind, honey bees and gravity all play role in pollination but there is no self-incompatibility. The cause of poor fruit set can be high percentage of male flowers.
The aonla fruit is one of the richest sources of vitamin C. It contains 500 to 750 mg of ascorbic acid per 100 g of pulp. This is much more than the vitamin C content of guava, tomato or citrus fruits. Only the Barbados cherry (Malpighia glabra) exceeds this figure. The small, round six-lobed fruits with hard pulp are astringent and not fit for eating fresh.
They are extensively used for making pickles and preserves. The astringency helps to preserve vitamin C in the ripe fruit, but even then most of it is lost in the process of pickling. When the fruit is treated with a 2 per cent salt solution, most of the astringency is lost, but the major part of vitamin C is also destroyed. If the fruit is put into boiling water for a few minutes before treating with the salt solution, a much greater quantity of vitamin C is retained.
Climate and Soil Required for Growing Aonla:
Aonla is a sub-tropical fruit but can be grown successfully in tropical climate. It is a hardy tree and can be grown in variable agro-climatic conditions. The mature plant can tolerate temperature as high as 46°C. However, it relishes distinct winter and summer for high productivity.
In India, it is being grown near sea coast to upto 1800 MSL. It can’t withstand much hot and frost but can tolerate mild frost under north Indian conditions. The tree can be damaged with the occurrence of severe frost.
Grafted plants are more prone to frost injury as compared to seedling plants. The young plants upto 3-4 years should be protected from hot desiccating wind in summer and heavy frost during winter. Low temperature from 7°C to 10°C is conducive for floral bud initiation.
After fruit-set in spring, the fruit remain dormant through summer without any growth, thus it makes the crop highly suitable for arid region. Aonla tree can tolerate drought for longer period. The Cultivar Chakaiya tolerates drought conditions better than the commercial cultivar Banarasi. The growth of the fruits takes place during July-August and at that time sufficient humidity is very useful to attain proper size.
Aonla trees can be grown on wide variety of soil ranging from sandy loam to clay loam. But, well drained, fertile loamy soil is best for aonla cultivation. It is a potential crop for degraded lands and the marginal soils having soil pH of 6.0 to 9.0. It has good tolerance to saline, sodicity and moderately alkaline soils.
Aonla is considered ideal plant for various kinds of wastelands and road side plantation. The areas having high water table should not be considered for aonla growing. Stagnation of water during rains is harmful for its growth and root system. It is high salt tolerant crop and has great possibility for commercial cultivation in salt affected soils. The cultivars Francis and Kanchan have better tolerance to sodicity and salinity than cultivar Banarsi.
The kandi area of Punjab is considered ideal for aonla cultivation and producing excellent quality good-sized fruits.
Orchard Cultural Practices for Growing Aonla:
i. Irrigation:
Aonla is generally cultivated as rainfed crop and little or no irrigation is provided. But for better establishment of orchard in early years few irrigation is essentially required.
After planting, young plantation should be irrigated at 3-4 days intervals and at 10-15 days intervals during summer. In bearing orchard, regular watering is needed for the development of embryo. Irrigate the plants at 10-15 days interval from March to mid-July in light textured soils.
During rainy season, no irrigation is given to the aonla orchards. During fruit development period in September and October monthly irrigation should be scheduled. The fruit maturity takes place from November to January, only one or two light irrigation can be given if need arises.
During peak winter period, if there are chances of occurrence of frost, light irrigation should be given to afford protection against frost. Avoid giving irrigation to aonla plants during flowering period.
ii. Intercropping:
During the initial 4-5 years of pre-bearing stage sufficient space is available for raising intercrops. In winter months from November to February when, tree has sparse or no foliage, vegetables like pea, cauliflower, spinach, tomato, brinjal etc. can be grown. Leguminous crops can be intercropped during pre-bearing orchard which enriches the orchard soil. The fillers like karonda, phalsa and ber can be intercropped in each square or between the tree rows to supplement the income during prehearing period.
iii. Mulching and Weed Control:
Mulching in aonla plantation is very helpful in minimizing water requirement and checking the weed growth. The surface area or tree basins are covered with organic or inorganic mulches during active growth period. Mulching with black polythene and paddy straw is found effective in induction of early and uniform flowering which regulate fruit maturity and produce better coloured fruits. The practice of covering the soil with black polythene is very effective in conserving moisture, checking weeds and reducing the fruit drop.
Organic mulch like straw, paddy straw, sugarcane trash, hay, banana leaves are also used in aonla orchards. The thickness of organic mulch should be 20-30 cm and not be in close contact of the tree trunk. Paddy straw mulch is commonly used in north India due to its easy availability. Mulching in aonla should be done during December-January after addition of manures and fertilizers.
The weeds can be removed by doing regular hoeing for better root growth and moisture conservation. Pre-emergence herbicide diuron @ 3 kg/ha in first fortnight of March or glyphosate @ 3 l/ha in second week of March in 500 litres of water can be sprayed to check weed flora in aonla orchards. An additional sprays of gramoxone @ 3 l/ha after rainy reason can be very helpful in controlling the weeds round the year.
iv. Manuring and Fertilization:
Aonla bear heavily and continue to bear upto about 50 years under proper conditions. The doses of manures and fertilizers are fixed on the basis of soil fertility, age of plant and productivity.
Under Punjab conditions, 15-20 kg farmyard manure is applied to young plants and 30-40 kg to mature plants during July-August. In addition, 30 g nitrogen per plant as applied for each year of age of the plant upto 10 years and afterwards 500 g of nitrogen to full grown plants.
In another fertilizer schedule followed by the growers, one year old plant is given 10 kg FYM, 100 g urea, 150 g single superphosphate (16% P2O5) and 40 g MoP (60% K2O). The doses are increased almost in similar way and stabilized at 10 years of age, when plant is given 60 kg FYM, 1 kg urea, 1.5 kg superphosphate and 1/2 kg muriate of potash. The whole quantity of FYM, superphosphate and muriate of potash and half quantity of urea is given in January – February before flowering. The remaining half quantity of urea is given during August.
In Rajasthan, five years old aonla plant is given 50-60 kg FYM, 600 g nitrogen, 300 g phosphorus and 375 g potash. FYM, phosphorus and half potash and nitrogen is given in February before flowering. Remaining nitrogen and potash is applied during August.
Boron deficiency occurs in aonla plants which cause problem of necrosis. Spray application of borax @ 0.6 per cent in September – October at fortnightly interval has been suggested. If zinc and iron deficiency is noticed, a spray of 0.5 per cent zinc sulphate and iron sulphate can be given for their correction. Soil application of zinc sulphate @ 250-500 g per plant is beneficial to overcome the zinc deficiency.
Propagation Techniques for Aonla:
Aonla is raised both through sexual and asexual methods of propagation. Seed propagation is though a commonly used in various parts of the country but does not ensure true-to-type plants due to cross pollination. Aonla is now commercially propagated through patch budding during June-September.
The fruits of seedling aonla (desi) are collected during January-February and seeds are extracted and used for raising of rootstock. The seed should be sown in first fortnight of March in north India. The seeds can be sown on seed beds or in polythene bags. The seeds can be soaked in GA3 @ 500 ppm for 24 hours to improve the germination percentage. The seeds germinate in 5-7 days and within 4-6 months plants become ready for budding.
Patch budding is done when the seedling become 1.0 to 1.2 cm in diameter at 15 cm above the ground level from June to September. When the bud take has occurred, the rootstock should be cut above the bud union. When the shoots from the bud attain a length of 15 – 20 cm, retain the vigorously growing shoot and remove the weaker one. The suckers below the bud union needs to be removed regularly to attain a good sized healthy plant.
The vegetative propagation can be done with forkert method of budding which give high success from July to September. The plants can be propagated through T-budding method during rainy season from July to September. This method also gives high success up to 80 per cent. Inarching or approach grafting can also be practised. Use of poly and net house, containers and rooting media proved useful in multiplication of aonla plants.
Flowering and Fruiting in Aonla Trees:
Flowering in aonla takes place on new determinate shoots begin to appear at the nodes in spring season. The flowering takes place from March to May in north India. Aonla tree is sensitive to day length. Flower bud differentiation takes place in first week of March. In South and West India, flowering occurs in June-July.
Male flowers appear in clusters in the axil of leaf all over the branchlet. Female flowers appear only on the upper end of a few branchlets. Early flower initiation was found in cv. Chakaiya and late initiation in cv. Kanchan. Initial fruit set in aonla varies from 12 to 18 per cent. Fertilization takes place within 36 hours after pollination.
Immediately after fertilization, zygote rests for 120-130 days and endosperm nucleus may rest for 70-80 days after fertilization in cv. Banarasi. Thereafter, fruits do not show any growth during summer months. Dormancy breaks as a result of division in endosperm nucleus in end July to early August. Fruit starts growing, continuously and maximum growth occur in the month of September.
The fruit growth follows a pattern of double sigmoid. The growth of fruit after dormancy is slow in first fifteen days. It shows rapid growth from mid-August to early October. The growths of fruits slow down again between second week of October to early November and registered slight increase after that. It ceases to grow after November. The seed length and weight increases rapidly during first rapid growth period of fruits when their size varies from 1 to 3.5 cm.
Fruit is drupaceous with a freshly exocarp. Endocarp is thick and massive. The fruits attain maturity in end November to early December and continue ripening upto February. At maturity and ripening, fruits become dull and greenish yellow.
Pollination:
Aonla is a cross-pollinated plant. Honeybees are the main pollinating agent. Winds also play an important role in pollination process. Pollen viability and pollen grain germination varies from 82-96 and 16.7 to 37 per cent, respectively. Most of the aonla cultivars are self-incompatible and need pollinizer in order to improve fruit set and retention. Krishna (NA-5) and NA-6 are found to be best pollinizer for NA-7 cultivar.
Harvesting and Handling of Aonla:
Budded aonla plants start bearing after 4-5 years of plantation and the trees starts giving regular yield at the age of 10 years. Seedling trees give commercial bearing after 10-12 years. Productive life of aonla tree is 50-60 years.
The fruits are ready for harvest in November- December in North and West India and continue bearing upto the month of February. The availability of fresh aonla in South India is from March to December and in East India from October to January. Aonla fruits should be harvested at full maturity.
Maturity can be judged by the change of seed colour from creamy white to black or by development of translucent exocarp. Fruits are harvested individually or fully loaded branches can be cut. Shaking of tree is not a good practice and fruits should not be allowed to fall on the ground.
The injured fruits cause spoilage to good fruits during packaging, transpiration and storage. Banarasi, Krishna and NA-10 are early maturing cultivars. Francis and NA-7 are mid-season cultivars whereas Chakaiya and Kanchan are late maturing cultivars.
Ladder can be used for ease in harvesting. Use of plastic trays is good for collection and transportation of fruits. All the fruits on the tree do not ripen uniformly. Therefore, two to three pickings should be done for harvesting of all the fruits on the tree. Peduncle should be properly clipped to check the spoilage during transportation. The bearing trees of different varieties can yield 100 to 150 kg fruits per tree.
The fruits should be graded into three grades viz A, B and C grades on the basis of size. In general, the fruit diameter should be 4 cm and above in A grade and less than 4 cm in B grade. All the defective fruits should be placed in C grade. Both A and B grade healthy fruits are used for preserve and candy making.
It is common practice in industry that small-sized fruits are used for making Chyawanprash. The fruits are commonly packed in gunny bags and baskets. However, the fruits should preferably be packed in CFB boxes for profitable marketing.
Aonla fruits are highly perishable in nature. The fruits should be handled quickly as period between harvesting and consumption is very limited. Shelf life of aonla fruits at ambient temperature is about one week but can be extended upto 120 days by storing in perforated polythene bags. The spoilage starts after a week at room temperature which is caused due to blue mould.
The fruits can be kept at low temperature (10°C) for two weeks. Shelf life of fruits may be extended upto 75 days in 15 per cent brine solution. Pre-harvest spray of calcium nitrate 1 per cent proved beneficial in extending storability of fruits at ambient temperature.
Varieties of Aonla:
The important cultivars of aonla are Banarasi, Chakiya and Francis etc. Some new strains of these have been developed at N.D.U.A.T., Faizabad (U.P.)
The important ones are:
1. Krishna:
A selection from Banarasi, is semi tall and early fruit maturing but shy bearing.
2. Narendra Aonla-10:
A seedling selection from Banaras is locally known as “Agra Bold”. It is semi tall, earliest maturing, moderate bearing but mildly susceptible to fruit necrosis.
3. Kanchan:
A seedling selection of Chakiya, is a tall tree, late maturing, profuse bearing and free from fruit necrosis.
4. Narendra Aonla-6:
Another chance seedling of cultivar Chakiya, is tall, semi- spreading growth habit, late maturity, moderate to profuse bearing, free from fruit necrosis.
5. Narendra Aonla-7:
A selection of Francis is a tall tree precocious profuse bearing and free from fruit necrosis and good for preserve making and processing.
Aonla can be grown in light, as well as heavy soils except very sandy soil. The trees are well adapted to dry conditions and can grow on saline or alkaline soil. It is a subtropical fruit but also thrives in tropical climate. It grows from the sea-coast to an altitude of 1,800 metres. The young plants should be protected from hot winds during May- June and from frost during winter, at least up-to the age of 3 to 4 years, under North Indian conditions.
Aonla is successfully propagated by budding in the month of June. Inarching gives weak plants with poor survival. Seedlings are used as rootstock. Soft wood grafting is also successful. The budded plants are planted 10 m x 10 m apart during rainy season. The plants are trained with a single stem up to 0.75-1.0 metre. Light pruning of the bearing plants is done after harvesting.
The young plants require irrigation at fortnight intervals during summer. Mature trees, require irrigation between flowering and fruit set to improve fruit set and reduced fruit drop.
The young plants should be manured with 20 kg FYM and bearing plant with 30 to 40 kg FYM per year in September-October. The tree should be fertilized with 30 g N for each year up to the age of 10 years. Afterwards 700 to 900 g of N per plant every year should be given in addition to 1 kg super phosphate and 1.0 to 1.5 kg of muriate of potash. The fertilizer should be applied in two split doses i.e. September-October and April-May.