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Cultivation and processing of litchi in Pakistan.

M. M. Nazri (Food Technologist)

Pakistan has successfully grown fruits like Mango and Banana. It is now trying to grow pineapple. Even though Litchi has grown in some areas of Punjab its quality is inferior and output insufficient. But the fact remains that Litchi can be grown successfully in some parts of Punjab, in N.W.F.P. and Hyderabad Division of Sindh.

Litchi to produce of good quality and in large quantities the following methods will have to be adopted.

Litchi is perhaps the most delicate fruits of tropical and subtropical countries. It loses its natural freshness rapidly after harvest.

Southern China is stated to be the home of Litchi where it is very popular. China, India and South Africa are presently major producers of Litchi in the world.

It is also produced in considerable quantities in Bangladesh, Campuchea, Taiwan, Japan, Newzealand, Australia, Madagascar, Thailand and U.S.A. (in Hawaii and Florida).

In India its production has reached about 3 lakh tons, and in its Bihar Province more than half of it.

In Pakistan where Litchi was grown some years ago, mostly in some districts of Punjab, its production is very low not even 3000 tonnes a year.

Botanically known as 'Litchi Chinesis' the height of its tree is about 10 to 12 meters and yield 15 to 100 kgs., depending on the cultivator. The ripened Litchi is consumed fresh. It is processed also as canned, frozen and dehydrated product for commercial purposes.

Soil & Climate

Litchi requires well drained deep loamy soil preferably slightly acidic, for its growth. It is less amenable to neutral or alkaline soils. Bihar province of India is no doubt an exception where it grows on soils containing 30% lime (calcareous alluvial soil). Litchi requires high humidity, occasional rainfall and cool dry weather free from frost and hot winds. A rainfall of 125-150 cm is necessary for its successful growth and development. A temperature of 21-38|degrees~C and relative humidity of 69 to 84% during the flowering of the fruit is necessary.

Young Litchi trees are highly susceptible to frost and must be protected against it during the first 3 to 4 years. However old and mature trees do withstand mild frost, but their resistance varies according to variety, age and conditions of growth.

At major factor, which prevents its cultivation in some parts of India (Bihar, UP, Punjab and Haryana) is the dry and hot wind "Loo" which prevails there between April and June the period when Litchi fruit is matured.

Indian scientists have recommended large red rose scented, "Gulabi" and Seedless ones for cultivation in UP and Bihar. Pakistan can also grow these varieties. In Calcutta (India) late seedless varieties have been found to be more resistant to hot wind and are well suited to hot regions, provided water is available for irrigation in sufficient quantity.

The heavy variety, Panjore common of India has been found suitable for growth in commercial quantities in Punjab and Haryana.

Propagation

Litchi is propagated by seeds or vegetative methods. Trees raised from seeds require 7 to 12 years to yield fruit, but its quality is inferior and in contrast vegetative propagation by layering, budding and planting gives better results. Hence this method is preferable.

Air Layering: It is a method largely practised in most countries, including India. The rainy season from June to August is favourable for its use. It depends on temperature, relative humidity and root producing tissues also.

Four to six weeks are required in India for root development during the monsoon season. Treatment of ringed shoots with 50% aqueous solution of Rootone or 100 ppm of alpha-naphathalene acetic acid (alpha-NAA) in lanolin paste is reportedly successful. Treatment of ringed shoots with indolebutyric acid (IBA) is also helpful in root formation. The use of IBA at 1500 ppm concentration has been shown to induce the highest number of roots as well as the highest root weight per gooty.

Wrapping in gunny cloth, mossgrass and polyethylene and their various combinations have been tested for improving the air-layering technique on late seedless variety. Out of these different combinations, propyethylene - mossgrass combination was found to be suitable.

Cultivation

Young Litchi plants are pretty delicate and highly prone to heavy mortality due to frost or hot-dry winds. Tall-growing trees such as seedling mango, Jamun and Eucalyptus are planted 2 to 3 years prior to the planting of Litchi plants to serve as wind breakers.

Litchi plants are raised during monsoon and spring seasons with light and liberal irrigation respectively. Complete drying up of the soil is not allowed to prevent adverse effects on the beneficial fungi present in the root nodules. The best planting period lies between August and September which may extend upto November, as practised in Punjab. Planting of Litchi is done on square or hexagonal pattern, square system being more prevalent. A spacing of 8-12 meters separates the rows as well as the individual plants.

Physico-Chemical Composition

Litchi is normally grown in UP, West Bengal and Bihar. In Litchi glucose is found to be the main sugar content with smaller amounts of fructose and sucrose protein, fat minerals are also found in smaller quantities.

Litchi - Yield and Harvesting

During the growth and development of the fruit on the plant, its weight, specific gravity, TSS, total sugars and reducing sugars continue to increase till its harvest. Upto 34 days after set, the skin percentage is more than that of seed but a reverse trend was observed after this period. The pulp begins to form after 34 days. The acidity of the pulp gets reduced with progressive maturation of the fruit. The respiration rate of the fruit is high in the initial stages, but it declines with progressive development of the fruit after the 31st day following fruit set. At the time of harvest maturity the respiration rate again decline, followed by high specific gravity and low acidity.

The fruit of most Litchi varieties in India are considered mature for harvest in 98 to 106 days after the bloom. The fruits are found to take 7-8 weeks to attain harvest maturity after the fruit set. In Calcutta variety the fruits are found to be ready for harvest in 55 days after fruit set, with the attainment of bright rosy colour and flattened tubercles. The fruits of Shahi and China varieties are ready for harvest in 49 and 55 days respectively after fruit set.

Harvesting

Harvesting of Litchi fruits begins in the second week of May in India and continues till the last week of June depending on the variety and the region of cultivation. Harvesting is not done during or soon after the rains since wet fruits get spoiled during storage. Immediately after harvest, the fruit clusters are kept in shade to minimize quality deterioration resulting from exposure to sun. Unpacked fruits kept at room temperature (RT) do not remain unspoiled for more than 72 hours after harvest. Desiccation and loss of red colour of the peel starts becoming visible. The next stage is browning of the peel due to enzyme activity, presumably involving aerobic oxidative polyphenase system which is triggered to function by desiccation. This can be avoided by suitable packaging and other measures.

Yield

Litchi trees begin to bear fruit from 3 to 5 years after planting in North India and 6 to 7 years in South India. The yield continues to increase for 25 to 40 years. Generally, mature trees (25-40 years of age) bear larger fruits. The annual yield of fruits per tree varies from 40 to 106 kg depending on the variety.

Storage

Storage life of Litchi, without any treatment, does not exceed 3 days at ambient temperature. For colour retention serious problems have to be faced. The storage life is extended by using polyethylene bag, paper wraps, etc. all these helps in reducing physiological losses in weight.

A storage life of 7-10 days in fresh condition at ambient temperature was achieved in the case of Litchi by treatment with hot water at 50|degrees~C for one minute followed by coating with paraffin-based wax emulsion and gamma irradiation and with packing in small punnets and over wrapping with cling plastic films.

The recommended optimum low temperature and relative humidity are 0|degree~C and 90% respectively. The expected storage life is 5 to 6 weeks (mentioned in recommended conditions for cold storage of perishable produce, International Institute of Refrigeration France 1967). However, the storage life can be further improved with different physical and chemical treatments.

Processing of Litchi

Litchi is highly perishable fruit available in short period. Slightly variations can be marked in the availability of Litchi produced. Seasonal gluts are also a common problem. Hence, the fruits are preserved by bottling, canning, drying, dehydration and freezing.

The processing of Litchi include some important steps such as selection, sorting extraction of juice/pulp bottling and canning care should be taken to avoid wastage. Semi-automatic and automatic machine/equipment are used in large scale processing for home scale production, stringer, hand operated juice extractor scooping knives are necessary.

Litchi Pulp

The peels and stones are removed the pulp heated and filled in bottles and immediately sealed. The bottled filled with pulp is processed in boiling water and cooled in air and stored in cool and dry place.

Freezing

Peeled, deseeded and sliced litchi fruits along with sugar syrup are filled in cans and frozen at -18|degrees~C. The storage life is reported to be about 12 months.

Dehydration of Litchi

Dried Litchi is known as lycheenut in USA and has an export potential. The fruits are washed and blanched for 5 minutes or in steam of atmospheric pressure for 15-20 minutes, followed by immersion in 2% KMS for 48 hours and dried in sun by spreading on suitable wire trays. The moisture content of the fruits should not be more than 3%.

Mechanical Drying

Both peeled and whole litchi fruits can be dehydrated by mechanical means. In this method, the fruits are thoroughly washed, blanched for 2 to 3 minutes in boiling water, sulphured for 5 hour in sulphuring chamber so as to have around 2500 ppm of sulphur-dioxide in flesh. The sulphured fruits are loaded on trays (1.25 kg. per 900 sq. cm) and dehydrated in two stages in a cross flow dehydrator of 72-75|degrees~C for 18 hours and then at 65|degrees~C for 12 hours to get a moisture content of around 2% in the finished products. The final product packed and kept at a cool and dry place.

Canning of Litchi

For canning purposes the Litchi fruits are used within 24 hours after harvest to get good result. The fruits are washed, peeled, destoned, blanched in hot water for about 1 minute and a syrup of 30o Bix with 0.05% Citric Acid added, exhausted, sealed and processed the cans and immediately cooled in running cold water.

The writer when he was incharge (General Manager and Technical Advisor) of a large Food Processing Factory in Dhaka canned Rajshahi variety of Litchi which became very much popular in the country (East and West Pakistan) the Litchi can also be canned successfully in Pakistan and people can have delicious taste of canned Litchi.
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Author:Nazri, M.M.
Publication:Economic Review
Date:Feb 1, 1993
Words:1868
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