3. OVERVIEW OF LYCHEE PRODUCTION IN THE ASIA-PACIFIC REGION

S. K. Mitra ^[3]

1. INTRODUCTION

Lychee (Litchi chinensis Sonn.), which originated in southern China and possibly northern Viet Nam belongs to the Sapindaceae family. The Sapindaceae is a relatively large family containing at least 125 genera and 1,000 species, which are widely distributed in the tropics and warm sub-tropics. The most widely cultivated fruit trees in this family other than lychee are rambutan (Nephelium lappaceum L.) and longan (Dimocarpus longan Lour.).

The main centre of origin of lychee is believed to be between latitudes 23° and 27° north in the subtropical parts of southern China, northern Viet Nam, and Malaysia. It seems to have been in cultivation since about 1500 BC by people of Malayan descent and has since been subjected to intense selection. China has a long history of lychee cultivation for more than 2000 years and from China it reached Burma (Myanmar) by the end of 17^th century and was introduced in India and Thailand about 100 years later. Lychee reached Madagascar and Mauritius around 1870 and was introduced in Hawaii in 1873 by a Chinese trader. It arrived in Florida, from India, between 1870 and 1880 and was introduced in California in 1897. Lychee was probably brought to Australia by Chinese migrants in 1954 and arrived in Israel sometimes between 1930 and 1940. China, Taiwan Province of China, Thailand, India, South Africa, Madagascar, Mauritius and Australia are now major lychee producing countries in the world.

2. PRESENT SITUATION OF LYCHEE CULTIVATION IN THE ASIA-PACIFIC REGION

Lychee is widely spread across south China, between latitudes 31° and 18°N and longitudes 101° and 120°E, whereas the commercial production zone lies between latitudes 19° and 24°N (Wu, 1998). In south China lychee has become a major industry since the 1980s. It provides huge scope for employment of the local populace and about 320,000 people are involved in this industry. In 1999, lychee output was about 950,000 tonnes from 530,000 hectares for China as a whole. Guangdong Province is the most important area for lychee production in China. Other provinces where lychee grows well include Guangxi, Fujian, Hainan and Yunnan (Chen and Huang, 2000).

In India lychee is grown mainly in the states of Bihar, West Bengal and Uttar Pradesh. It is also grown in limited scale in Tripura, Orissa, Punjab, Himachal Pradesh, Assam and the Nilgiri hills in the south. Current production of lychee is about 429,000 tonnes from an area of about 56,200 hectares (Ghosh, 2000).

Lychee is mainly grown in the northern part of Thailand where the climate is classified as sub-tropical. The major concentrations are in Chiang Mai, Chiang Rai, Phayao and Nan provinces in the north and Samut Songkhram in Central Thailand. The production of fresh lychee fruit in Thailand during 1999 was 85,083 tonnes from 22,200 hectares.

Northern Viet Nam includes part of the geographical area where lychee originated. This species has been grown commercially for many centuries near Hanoi, but production has only expanded rapidly in the past five years. The total area under cultivation is about 25,000 hectares, with 10,000 hectares under bearing trees and the total production in 1998 was 27,000 tonnes (Ha Min Trung, 2000).

Lychee is mostly grown in central and southern Taiwan Province of China. The total area under cultivation in 1999 was 11,961 hectares, with 11,580 hectares of bearing trees and 108,668 tonnes of total production (Anon., 2000).

In Bangladesh, lychee is grown in Dinajpur, Rangpur and Ragshahi districts. The total area under cultivation in 1998 was 4,750 hectares with 12,755 tonnes of total production.

Although lychee was introduced into Australia about 60 years ago, major commercial plantings commenced only from the 1970s. Currently, there are about 350 growers with an annual production of about 3000 tonnes. About 50 percent of commercial plantings are found in northern Queensland, 40 percent in southern Queensland, and the balance in northern New South Wales (Menzel, 2000).

3. CULTIVARS

The Chinese consider that the lychee has more cultivars than any other fruit crop. Although over 200 cultivars are grown, only about eight are commercially important in China. In Guangdong Province, the cultivars Baila, Baitangying, Heiye, Feizixiao, Gwiwei, Nuomici and Huaizhi are being cultivated commercially and each of these cultivars covers more than 20,000 hectares. However, Guiwei and Nuomici are most widely cultivated (more than 60,000 hectares under each cultivar). In Fujian Province, Lanzhu is the main cultivar covering about 25,000 hectares (Chen and Huang, 2000).

The most important cultivar of Taiwan Province of China is Hap Ip, which accounts for about 90 percent, and is followed by Yu Her Pau (in the southern area) and No Mi Tsu (in the central area) (Yen, 2001).

The dominant lychee cultivars of India are Shahi, Bombai, China, Deshi, Calcutta, Rose Scented and Mazaffarpur (Ghosh et al., 2000).

There are over 40 cultivars of lychee in Australia. Cultivars currently being planted in northern Queensland on the Atherton Tablelands and coast include Kwai May Pink, Fay Zee Siu and Souey Tung. Kwai May Pink is also popular in central and southern Queensland and in northern New South Wales, along with Salathiel and Wai Chee.

In Thailand the main cultivars are Haak Yip, Tai So and Wai Chee (locally known as Baidum, Hong Huey and Kim Cheng). The lychee cultivars of Thailand are, however, divided into two groups, namely the lowland lychee or the tropical lychee and the sub-tropical lychee. The tropical lychee is well adapted and commercially grown in the Central Region with warm winter months. Almost 20 cultivars are known in this group. The sub-tropical group of lychee grows in the northern part of the country where the winter months are rather cool. About 10 cultivars are known in this group (Yapwattanaphun and Subhadrabandhu, 2000).

A number of local cultivars are found in the northern mountainous provinces of Viet Nam, but most of these are low yielding and sour. There are a number of local cultivars in Ha Tay province (Trang Cat, Yang Anh and Vai Do). The main cultivars are Thiew Thanh Ha, hybrid lychee and Phu Ho. Thiew Thanh Ha is the most popular and more than 90 percent of the production is from this cultivar. Seven cultivars were also imported from Australia and planted in the Luc Ngan District and Ha Giang Province of which Wai Chee and Salathiel appear the most promising.

4. CLIMATIC REQUIREMENTS

The lychee is adapted to the warm sub-tropics, cropping best in regions with brief, dry, frost free winters and long, hot summers with high rainfall and humidity. Poor production is experienced in most countries. This is often because winters are not cool or dry enough to induce a growth check prior to flowering. Irregular flowering in lychee is related to variations in the timing of flushing. If early flush development, when buds3 swell, coincides with days of 20°C or cooler, then flower panicles will be initiated. On the other hand, if the warm or the cool weather arrives when the buds are longer than a few millimeters, then the flush will be vegetative (Batten and McConchie, 1995; Menzel and Simpson, 1994). In some parts of southern Queensland, Australia, winter frosts may damage the panicle and developing flowers and limit fruit production in that season. In China, conditions during flowering are often cool and overcast. This can prevent pollination and fruit set. More frequently, conditions during spring and early summer in Australia are hot and dry. Similar conditions are found in the lychee areas of northern India. Flowers may dehydrate and fail to develop, while fruit may drop or split. This is because lychee has a low ability to transport water from roots to leaves. Wet soil alone cannot prevent the development of tree water stress. In Thailand, however, the cultivars are divided into two groups according to temperature requirements for flowering: (i) the cultivars that require no or only a short cool period for flowering (for the central part of Thailand); and (ii) the cultivars that require a longer cool period for flowering (for the northern part of Thailand). In India, the major producing state is Bihar (more than 40 percent of the total area under lychee in India) where a longer cool period before flowering is available in most years. In West Bengal, occasional hot and dry conditions prior to flowering restrict production.

5. PLANTING DENSITY

Traditionally, lychee trees were planted with wide spacing of 9 or 10 m x 12 m or even 12 m x 12 m, with about 70-80 trees per hectare. Such plantings can have very high yields on a tree basis after 10 or 15 years, but are wasteful of land in the early years. Also, with large trees there are problems with harvesting, spraying and protection from birds and bats (Menzel et al., 2000). The old plantations in India, Australia, Thailand, and China were planted at a density of 80 to 150 trees per hectare. New orchards in Australia are planted at a closer spacing of 6 m x 8 m or 4 m x 6 m or 7 m x 3 m, equivalent to 200 to 600 trees per hectare (Menzel et al., 2000). In China, starting from the 1980s lychee trees were planted in closer spacing, popularly 5 m x 4 m or 6 m x 5 m, i.e., 330-500 trees per hectare. There are also some extra dense orchards containing 1500 trees per hectare (3 m x 2.5 m) (Chen and Huang, 2000). In India different planting systems (square, hedge row, double hedge, paired planting and cluster planting) as well as density (204 to 453 plants per hectare) are now being investigated under the All India Coordinated Research Project in different locations. Initial results have shown that hedgerow planting is more remunerative during early fruiting years.

6. NUTRITION MANAGEMENT

One of the major factors limiting fruit production in lychee is lack of a suitable nutrition programme. Yields may be low because of excessive vegetative growth in winter following late or heavy N fertilization. Deficiencies of N and K, and to a lesser extent of B, Zn and Cu, may limit yield by restricting the set and subsequent development of fruit. Although leaf nutrient standards are available for China, Australia, Thailand and India lychee growers usually apply fertilizers based on canopy sizes, fruit loads or tree age. In China the recommended annual dosage is 0.6 kg urea, 1.2 kg super-phosphate and 0.6 kg of potassium chloride on a five-year-old tree basis, with the N:P:K ratio of 1:0.96:1.3. Fertilizers are generally used separately in three stages, i.e. inflorescence emergence (early to mid-January), rapid fruit growth (early to mid-May) and the time to stimulate autumn flushing (late June to July). However, in most orchards fertilizers are applied frequently and in small doses each time (in many cases over 10 applications of both soil and foliage sprays). A fertilizer schedule based on tree age and canopy size is available for Australia (Menzel and Simpson, 1989). However, these rates are considered as a guide and should be supported by leaf and soil analysis. The suggested rates for a 10-11-years bearing tree with 4.0-4.5 m canopy diameter and 12-16 m canopy cover are 500 g N, 170 g P₂O₅ and 700 g K₂O. The recommended application schedule being half the annual amount of nitrogen after panicle emergence and other half after fruit set. The other nutrients (P and K), are supplied in two equal applications, after panicle emergence and after harvest. In India, a fertilizer schedule based on tree age is available which, however, varies in different growing regions. Bearing trees of 7 to 10 years in age usually receive 400-600 g N, 200-300 g P₂O₅, 400-600 g K₂O and 40-50 kg organic manure annually. The full dose of organic manure and three fourths of the total inorganic fertilizers are applied in June-July after harvesting. The remaining one-fourth inorganic fertilizers are applied in early April when fruits grow to pea size.

Tentative leaf nutrient standards based on survey of high-yielding trees in southern Queensland, Australia are available for lychee. Leaf nutrient levels for Guangdong and Guangxi Province of China and for India are also available.

Tentative standard leaf nutrient levels for Australian lychee orchards after panicle emergence during May-August are: 1.50-1.80 percent for N, 0.14-0.22 percent for P, 0.70-1.10 percent for K, 0.66-1.00 percent for Ca, 0.30-0.50 percent for Mg, 50-100 mg/g for Fe, 100-250 mg/g for Mn, 15-30 mg/g for Zn, 10-25 mg/g for Cu, 25-60 mg/g for B, <500 mg/g for Na and <25 percent g for Cl. The suitable leaf nutrient levels for Guangdong Province of China are suggested as 0.93-2.10 percent for N, 0.08-0.21 percent for p and 0.12-0.33 percent for K. In Guangxi, suggested levels are 1.766-1.78 percent for N, 0.25-0.28 percent for P and 0.75-0.92 percent for K. The suitable levels for microelements are 1.5-5.0 mg/kg for available Zn, 1.5-5.0 mg/kg for exchangeable Mn, 1.0-5.0 mg/kg for available Cu, 0.40-1.00 mg/kg for water soluble B and 0.15-0.32 mg/kg for available Mo.

7. IRRIGATION MANAGEMENT

In Australia, India and northern Thailand, trees are irrigated from flowering onwards until the completion of the post-harvest flush. Many orchards in Australia are watered two to three times per week, but this may be excessive. Indeed, in wet growing areas, such as those around Ballina and Nambour, irrigation might be ineffective in many years. In somewhat drier areas however, such as those around Mareeba and Bundaberg, irrigation is likely to be far more important, especially for successful panicle growth, flowering and fruit development. In India, trees it is suggested that trees be irrigated at 30 to 45 percent available soil moisture depletion. However, the growers practice is to irrigate the tree at 7-10 day intervals from panicle emergence to fruit harvest or until the post-harvest flush appears. While drip irrigation is in practice in most of the lychee orchards in Australia, northern Thailand and in some areas in China, surface irrigation (basin irrigation) is followed in India, Viet Nam, Bangladesh and Taiwan Province of China.

8. MANIPULATING FLUSHING CYCLES AND FLOWERING

Lychee trees initiate flowers when early flush development coincides with low temperatures. Consequently, flowering only occurs if new flushes develop during cool weather. Olesen and his co-workers (2000) from Australia suggested four possible ways to alter flushing and induce flowering in lychee. Trees can be hedged to induce one or two vegetative flushes over summer and autumn, and a second or third in winter or droughted in autumn to prevent more than one or two leaf flushes after the preceding harvest. They can also be pruned going into winter to induce flowering directly below the pruning cut. There is also the possibility of using ethephon (1 to 3 l of ethrel and 5 kg of urea per 1,000 l of water) to selectively remove the young red flushes in winter. Full recommendations (Agrilink) for the strategy will be available for Australian growers this year. However, a good flowering is no guarantee of fruit set or a good crop. Investigations by Yuan and Huang (1993) in China found that an extra peak of root growth in May was the characteristic of young 'Nuomici' lychee, which caused serious fruit drop. Zhou et al. (1996) found absence of this root growth peak in young 'Huaizu' and also bearing trees of 'Nuomici' showed less fruit drop. Positive response of spiral girdling was observed in China in speeding up the maturation of autumn flushes and in inhibiting winter flushing in favour of flower initiation, in increasing percentage of pistillate flowers, in overcoming excessive fruit drop and in improving fruit size and quality. It is recommended that for flowering, girdling should be made at a stage between the turning green of leaves and flower initiation during the winter, and for fruit setting, immediately after bloom. To promote flowering, 'Feizixiao' lychee trees are usually spiral girdled in mid-November, but 'Nuomici' and 'Guiwei' are spiral girdled in late-November/early December on trunks or scaffold branches 10 cm in diameter. However, to improve fruit set in 'Nuomici' and 'Guiwei' girdling is usually made in early May on branches 5 cm in diameter. The girdling width is 2 to 4 mm, with 1-2 spirals and the distance between two neighbouring spirals is about 6-10 cm. Experimental evidence is available from Thailand for flower induction of lychee in cv. Hong Huay by use of ethephon (100 ppm) (Subhadrabandhu and Koo-Duang, 1987) and in cv. Bombai by ethephon, potassium nitrate and TIBA spraying in the months of October-December (Mitra and Sanyal, 2000), however, large scale field testing is needed before any commercial recommendations can be made.

9. PROBLEM OF FRUIT CRACKING

Fruit cracking is a major problem of lychee in many lychee growing areas in India and China. Among the cultivars grown in India, Early Large Red, Deshi, Muzaffarpur and Elaichi are more prone to crack (Mitra and Ghosh, 1991) while the high priced Nuomici and Gwiwei cultivars in China are susceptible to cracking (Chen and Huang, 2000). Plant growth regulators and integrated management showed some positive results in lowering the cracking rate (Li et al., 2000).

10. MAJOR PESTS AND DISEASES AFFECTING PRODUCTION

Over 58 species of pests have been reported damaging lychee trees in China. Of these the major pests are lychee stink bug (Tessaratoma papillosa), lychee barking miner (Conopomorha sinensis), lychee longhorn beetle (Aristobia testudo), lychee midge (Dasineura sp.) and Erinose mite (Eriophyes litchi) (Ren and Tian, 2000). Erinose mite is the most serious pest of lychee in India, Thailand and Viet Nam. The macadamia nut borer (Cryptophlebia ombrodelta) is the most serious pest of lychee in Australia. However, the most devastating damage is caused by flying foxes amounting up to 50 percent of the crop loss in Australia. Fortunately, the lychee growers in other countries of the Asia-Pacific are not facing the problems of flying foxes. Protocols exist for control of most of the other pests in different countries. There are about 25 species of natural enemies of lychee pests. Of these egg parasitoid, Anastatus spp. for controlling stink bug, nematode Steinernema carpocapsae for controlling longhorn beetle and predaceous mite Agistemus exsertus for controlling erinose mite have been used successfully.

There are no serious diseases of lychee. The 'sudden death' phenomenon is, however, observed in Australia, China and Viet Nam. Initial findings suggest that sudden wilt is a soil-borne disease, associated with Fusarium solani, Phytophthora sp. and Phythium sp. Poor drainage, deep planting and inadequate nutrition favour the disease (Ha Minh Trung, 2000). A number of diseases affect lychee after harvest, which are generally not apparent during harvest and packing. They develop as the fruit reach the end of their post-harvest life. Several fungi have been associated with disease symptoms affecting the sides of fruit or around the stem end. Among the post-harvest diseases, anthracnose (Colletotrichum gloeosporioides) is mainly responsible for such loss in China, Australia, Taiwan Province of China, Thailand and India.

11. HARVESTING OF FRUITS AND YIELD

Only few fruits can be compared with the taste of a fully mature lychee fresh from the tree. If growers take care to harvest their fruit only when it is fully mature and then grade, treat and pack it properly, consumers can enjoy that same delicious flavour, and the market for the fruit will develop quickly. Maturity standards based on TSS/acid ratio, fruit weight, peel colour etc., have been standardized for most of the commercial cultivars of India, Australia, China, Taiwan Province of China and Thailand. Lychees are harvested manually in bunches along with a portion of the branch and few leaves. The panicles are cut from the tree with secateurs or harvester meant for the purpose. In most countries, ladders, cherry pickers and picking bags are used.

Average lychee yields range from 1 to 15 tonnes per hectare in different countries of the world. In Taiwan Province of China, the productivity is about 9.4 tonnes/ha compared with 7.63 tonnes/ha in India, 3.83 tonnes/ha in Thailand, 2 tonnes/ha in Viet Nam, 1.8 tonnes/ha in China and 1.66 tonnes/ha in Australia.

12. POST-HARVEST MANAGEMENT

Once lychees are picked, they start to dry out and brown. The mechanisms of pericarp browning, colour retention, and pulp quality maintenance have been the worldwide focus of lychee post-harvest biology research. Progress has been made in lychee pericarp browning and colour maintenance. Fruits should be kept in high humidity and cooled to 5°C as quickly as possible. Hydro-coolers or cool rooms are frequently used for this purpose. Sulphur fumigation has so far been the main post-harvest handling technology in prevention of lychee browning and maintenance of fruit quality. However, it has recently been questioned by both scientists and customers due to the chemical S residues and off-putting taste.

At the moment the cool-chain system can provide satisfying resolution to lychee transportation, storage and marketing problems in developed countries. However, the cool-chain system is still at the very early stage of establishment in developing countries such as China, India, Thailand, Viet Nam, Bangladesh and some other Asian countries.

13. INTERNATIONAL TRADE

Among the major international markets Hong Kong and Singapore receive approximately 12 to 15 thousand tonnes of lychee from China and Taiwan Province of China during June-July. Taiwan Province of China exported about 5,900 tonnes of lychee in 1999, and the main destinations were Philippines (1,735 tonnes), USA (1,191 tonnes), Japan (933 tonnes), Canada (930 tonnes), Thailand (489 tonnes) and Singapore (408 tonnes).

The European markets absorb about 20,000 tonnes of fresh lychee of which nearly 50 percent was imported by France alone and the rest mainly by Germany and the United Kingdom. The market is especially lively between Christmas and New Year's Day. The main suppliers are Madagascar (80 percent), and South Africa (12.6 percent) during this period. The same markets also receive a small quantity from Australia during Christmas and from Thailand between July and August (400 tonnes), India (about 25 tonnes), China and Taiwan Province of China. The lychee market in the United Arab Emirates, Saudi Arabia, Yemen, Lebanon, Dubai and Canada are expanding and can absorb a few hundred tonnes more fresh lychee. Except for Australia (exporting about 25-30 percent of the total production), the other lychee producing countries in this Region are exporting very little (0.2-5.5 percent) of their total production. The reasons are mainly that all the producing countries have a good domestic market and lack proper cool-chain and other exporting facilities. Small quantities of lychees are, however, frozen and canned (about 2,500 tonnes in China, and 500 tonnes in Taiwan Province of China) and exported to Japan, USA, Canada, Malaysia, Republic of Korea and Australia. About one third of the total production of China (300,000 tonnes) was dried in 1999 as lychee nut, which were marketed domestically and also exported to Southeast Asia.

14. DEVELOPMENT STRATEGY

The expansion of the fresh lychee market will depend mainly on: (a) availability of high quality fruits in abundance, (b) availability for a longer period by lengthening of fruiting seasons, and (c) emergence of new supplier countries capable of transporting fruits by sea.

China is rich in lychee germplasm of lychee and some high yielding, good quality lychee cultivars/clonal lines have already been identified. Further breeding efforts, including molecular breeding, offer good scope for developing promising cultivars of lychee for greater adaptation and higher yield. Already, the major production zones in this Region are distributed in such a way that good quality fruits are available both in November-December (Australia) and May-August (India, China, Taiwan Province of China, Thailand). The experience of Israel, Taiwan Province of China and Mauritius has shown that further lengthening of the fruiting season is possible. Technologies to enhance shelf life through temperature management during storage and transportation are available. Consequently, the supply of good quality lychee for fresh fruit markets all the year round should receive a major development thrust.

Market restructuring for lychee is essential. Presently Europe is the main destination and fresh fruit is the major commodity market. New markets and product diversification, new products, new packaging, organic lychee and others are new options.

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