1522

2: Edible fruits and nuts

Mangifera indica L.

Sp. Pl.:200 (1753).

ANACARDIACEAE

2n = 40

Mango (En). Manguier (Fr). Indonesia: mangga, mempelam. Malaysia: mangga, mempelam, ampelam. Papua New Guinea: mango (Pidgin). Philippines: mangga (Tagalog), paho (Bisaya), mango (Ilokano). Burma: tharyetthi. Cambodia: svaay. Laos: mwàngx. Thailand: mamuang. Vietnam: xoài.

The mango supposedly originated in the Indo-Burma region, that is in the margin of the area of distribution of the genus, and in fact in the subtropics. It has been cultivated in India for several thousand years, but its progenitors are not known. The mango spread throughout South-East Asia about 1500 years ago and to the east coast of Africa about 1000 years ago. Further expansion to Australia, West Africa and the Americas occurred during the last few hundred years. Although widely distributed in the tropics and subtropics, the mango remains the fruit of India, also through the role the tree plays in Hinduism.

Mango is cultivated for the fruit which can be eaten in 3 distinct ways, depending largely on the cultivar: unripe (mature green, very popular in Thailand and the Philippines), ripe (the common way to enjoy mango throughout the world), and processed (at various stages of maturity, in the form of pickles or chutneys, dried slices, canned slices in syrup, juice, puree or paste, etc.). The green fruit is also used to flavour fish and meat dishes in the same way as tamarind and other sour fruits.
Seed kernels form a by-product of processing; they can be used as feed for cattle and poultry. In India the kernels are also important as a famine-food, but the astringency has to be removed by boiling, roasting or soaking the kernels for a long time. Young leaves are eaten fresh or cooked as a vegetable. Dried flowers or bark and decoctions of the kernels serve as astringents in traditional medicine. Extracts of unripe fruit and of bark, stems and leaves have shown antibiotic activity.
The wood is fairly strong, hard and easy to work but it must be treated with preservatives when used in construction and outdoor applications. It makes excellent charcoal and is also used to culture mushrooms.

Annual world production in the late 1980s is estimated at 15 million t. The important mango-producing countries are India, Mexico, Brazil, Pakistan, Thailand, China, Indonesia, the Philippines and Bangladesh. Most of the production is for domestic consumption; minute numbers of fresh mangoes are exported. About 1 million ha are under mango cultivation in India (1982). Production was 308 600 t from 77 387 ha in Indonesia (1981), 27 300 t from 7900 ha in Peninsular Malaysia (1988), 289 000 t from 48 000 ha in the Philippines (1988), and 422 000 t from 183 500 ha in Thailand (1988). The volume of world trade in 1985 was approximately 90 000 t only, but international trade is increasing fast. The major markets for mango are in South-East Asia, Europe, the United States and Japan. Singapore and Hong Kong are the major mango importers in South-East Asia; they are supplied largely from Thailand and the Philippines. Japan currently imports mango from the Philippines and Thailand.

The mango fruit is composed of 11—18% skin, 14—22% flesh and 60—75% stone. Mango flesh contains per 100 g: water 78—85 g, protein 0.3—0.8 g, fat 0.1—0.2 g, carbohydrates 13.2—20 g, fibre 0.6—0.7 g, calcium 9—25 mg, phosphorus 10—15 mg, and iron 0.1—0.2 mg. Energy value is 225—350 kJ per 100 g. Mango is a particularly rich source of vitamins: 100 g flesh contains 14—62 mg vitamin C, 0.03—0.09 mg vitamin B1 and 0.05—0.08 vitamin B2.

Evergreen, erect, branched tree, conforming to Scaronne's architectural model, 10—45 m tall, 60—120 cm trunk diameter with long taproot and dense surface mass of feeding roots; bark greyish-brown, longitudinally fissured. Leaves spirally arranged, simple, produced in flushes; young leaves usually reddish, turning dark shiny green; petiole up to 10 cm long, with pulvinus at base; blade variable in size and shape, usually narrowly elliptic to lanceolate, 8—40 cm x 2—10 cm, somewhat leathery, tapering at base, margin often undulate, apex acuminate, nerves 12—30 pairs, elevated on both surfaces. Inflorescences terminal panicles, widely branched, up to 60 cm long, densely flowered, tomentose, bearing male and hermaphrodite flowers; flowers greenish-yellow, 5—8 mm in diameter, pedicels 1 mm long; calyx 5-lobed; petals 5, twice as long as calyx, creamish to pinkish; disk short-cupular, 5-lobed, fleshy; stamens 5, usually 1 fertile; pistil abortive in male flowers, style lateral, stigma simple. Fruit a fleshy drupe, very variable in shape, size and colour, usually ovoid-oblongoid, up to 30 cm x 10 cm, very unequal-sided, yellowish-green to reddish; exocarp fairly thick and gland-dotted; edible mesocarp variable, yellow to orange, fibrous or free of fibres, juicy and sweet to turpentine flavoured; endocarp thick, woody and fibrous. Seed inside endocarp, mono- or poly-embryonic, not labyrinthine.

The mango seedling (or seedlings in the case of polyembryonic seeds) emerges in 2 weeks and grows rhythmically from the start: a flush brings out the new shoot which extends in about 1 month time, after which the buds remain quiescent for shorter or longer periods. In a mature tree many twigs produce no extension growth for a year or longer, but in saplings most twigs flush up to 4 times per year if there is enough moisture. Flushes occur more or less synchronously depending upon the climate; during a long wet season the synchronization is gradually weakened. Leaves can remain functional for several years. The tree roots to a considerable depth, enabling it to find the moisture necessary for flowering/flushing during the dry season.
Normally only the buds at the compressed shoot tip partake in extension growth and flowering. Vigour finds expression in shoots of larger size and in the leafing out of more — often up to 5 — lateral buds at the shoot tip. A seedling mango comes into bearing after 5—7 years, some terminal buds producing an inflorescence whereas other terminals extend a flush of shoots. With the onset of bearing, the number of flushes is reduced to 2 or 3, including the dry-season flush which coincides with flowering.
Studies of several mango cultivars have revealed biennial flowering at the twig level, which means that shoots emerging from twigs which have flowered are unlikely to flower in their turn, even where flowering did not result in fruiting. Also, shoots of the last flush before flowering are less likely to break into bloom than twigs of previous flushes which have gone through much longer quiescent periods. In many Indian cultivars these tendencies are so strong that prolific bloom or late flushing necessarily lead to failure of the following bloom, thus leading to biennial bearing. It remains to be shown whether or not similar extremes occur in South-East Asian cultivars.
The inflorescence can reach full bloom from the time of flower initiation in as little as 25—30 days. Considering that each flower is a transformed shoot, an inflorescence is essentially as complex as a sizeable tree; hence the rate of organogenesis leading to bloom is astounding. Presumably the preceding quiescent period somehow paves the way for this explosive floral development. The fruits also grow fast: they ripen after 3—4 months, some late cultivars after 5 months.
Pollination is largely effected by insects (flies, bees); wind pollination is not very effective. Stigmas remain receptive for a short period only, mainly during the night and morning. Cross-pollination is recommended but polyembryonic cultivars in particular are often planted without pollinators. Fruit set is rather poor and variable, and losses due to premature drop occur right up to the harvest. Hence only about 1 out of 1000 perfect flowers can be expected to yield a fruit.

There are numerous cultivars and there is much confusion about their names. Cultivars can be classified in 2 groups:
— monoembryonic cvs, forming seed with a single zygotic embryo; seedlings not true to type. The large majority of Indian cultivars and their offspring belong to this group: 'Dashehari', 'Langra', 'Neelum', 'Pairi', 'Alphonso', 'Bombay', 'Mulgoa'. In Florida (selected from seedlings of Indian cvs): 'Irwin', 'Tommy Atkins', 'Zill', 'Ruby', 'Kent', 'Keith'. In the Caribbean: 'Amelie', 'Divine', 'Julie'.
— polyembryonic cvs, forming seeds with several adventitious embryos in the nucellar tissues. These are true to kind and in most cultivars tend to suppress the zygotic embryo. South-East Asian cultivars belong to this group. In Indonesia: 'Golek', 'Gadung', 'Arumanis'. In the Philippines: 'Carabao' (constitutes 2/3 of the crop), 'Pico', 'Pahutan'. In Thailand: 'Keow Sawoey' (consumed green), 'Nang Klangwan', 'Nam Dokmai', 'Tong Dum'. In Australia: 'Kensington'. In South Africa: 'Sabre', 'Peach' (both used in wetter highlands). In East Africa: 'Dodo', 'Boribo'. In Central America/Florida: 'Cambodiana', 'Manila'.

The mango thrives both in the subtropics and the tropics. In the subtropics the cold months ensure excellent floral induction, but late frosts are a major risk: tender parts of the tree are killed by frost. In the tropics the mango grows almost anywhere up to 1200 m elevation, but for fruit production a prominent dry season lasting more than 3 months is necessary. A flowering flush is produced during the dry season, but — contrary to the subtropics — flowering is erratic and a yield-limiting factor. At elevations above 600 m in the tropics the climate becomes too cool for the commercial cultivars, the optimum temperature being around 24—27°C. Rainfall ranges from 750 to 2500 mm per year in tropical centres of production.
Mangoes grow in a wide range of soils and moisture regimes. The trees are drought-tolerant, and on the other hand do not seem to suffer from occasional flooding. A deep (rooting depth 2.5 m) but rather poor soil is preferred; easy access to water and nutrients tends to stimulate growth at the expense of flowering. A high pH is less detrimental than acid soils, the preferred range being 5.5—7.

Polyembryonic cultivars used to be propagated mainly from seed, but budding and grafting are now becoming the rule, as was already the case for monoembryonic cultivars. Rooting of cuttings and layers is possible but not done on a commercial scale.
To obtain uniform rootstocks, seedlings are raised from polyembryonic cultivars, e.g. 'Madu' in Indonesia, 'Kaew' in Thailand, and 'Kensington' in Australia. Research programmes to identify suitable dwarfing rootstocks are showing promising results in India. Seeds lose their viability in a matter of weeks and are pre-germinated as soon as possible after extraction. They are placed on their sides, the dorsal (most prominently curved) edge upwards, to produce a straight stem and root. Germination can be hastened by removing the tough endocarp before sowing.
Grafting can be done at any rootstock age, the earliest moment being when the thinnest possible graftwood matches the girth of the rootstock (in about 8 weeks from sowing). The rootstock stem should be sufficiently woody and thick (pencil size) to support cuts for budding. There is no consensus about the best method: in Thailand inarching of bagged rootstocks in mother trees is preferred, in the Philippines wedge grafting, elsewhere often side veneer grafting or patch budding. High temperature (25—30°C), actively growing rootstocks and hardened scion wood are important ingredients for success.
Nursery work takes 1—2 years; trees are preferably planted early in the rainy season. In Thailand the recommended spacing ranges from 12—8 m x 12—8 m, that is 69—156 trees/ha. The closest spacing is on raised ridges in the Central Province where a high water table limits rooting depth and tree size.

In the tropics mangoes are mainly found in home gardens and scattered in non-irrigated fields or field borders. Orchards are common in the subtropics and gaining importance in South-East Asia: they dominate in Thailand and the Philippines.
Husbandry comes to the fore in mango orchards. Irrigation in the first years after planting promotes flushing (and suppresses flowering), so that tree size increases quickly. Irrigation also widens the scope for intercropping — e.g. with papaya, banana, pineapple or vegetables — during the establishment phase. When the trees are big enough to produce a substantial crop, irrigation is stopped, or at least interrupted long enough to impose quiescence leading to flower initiation. Trees of most cultivars have a dense canopy, and with a little weeding the orchard floor can be kept clean.
Numerous traditional methods exist to promote flowering of mango in the tropics: cincturing the trunk or branches, root pruning, exposing the roots for a few weeks by removing the topsoil, applying salt in a furrow round the tree, and smudging (smoking the orchard for several weeks with trash fires). These methods are laborious and far from foolproof, but growers hope to advance as well as to promote flowering in order to get a much higher price for their crop. Smudging used to be employed in the Philippines. There is evidence that ethylene is the active ingredient in the smoke and spraying ethylene-releasing compounds proved an effective alternative. However, spraying potassium nitrate (KNO₃) has superseded smudging and ethylene, as it is a simple and reliable method for the leading cultivars 'Carabao' and 'Pico' in the Philippines. As a result yields are much higher and more stable. However, experiments on other cultivars and in other countries have so far failed to yield convincing results, and the way in which KNO₃ affects flowering remains obscure. Meanwhile there are indications that the growth retardant paclobutrazol has similar effects as KNO₃ on a wide range of cultivars in different countries.
Fertilizer recommendations seem rather whimsical and there is no agreement on standard leaf nutrient levels. Different sources agree that liberal amounts of nitrogen stimulate growth at the expense of flowering and that fertilizers or manure should be applied shortly after harvest (to encourage the post-harvest flush) and just before bloom (to aid fruit growth). In the absence of irrigation the topdressing can only reach the roots if applied well before the end of the rainy season; the hoped-for effect of application at that time is stronger flowers which remain fertile for a longer period, resulting in better fruit set. The following figures are an estimate of the nutrients extracted by the crop (in kg/t fruit): N 6.5, P 0.75, K 6.2, Ca 5.5 and Mg 2.9. The low phosphorus extraction corresponds to the low P-levels in several — but not all — fertilizer recommendations. The fruit contains much potassium and this should be balanced by adequate Ca and Mg levels to avoid physiological disorders in the fruit.
Some formative pruning is practised to shape young trees, but thereafter trees are usually left unpruned till the ageing lower limbs need to be removed. In Thailand annual pruning of watersprouts and overlapping branches is recommended. Biennial flowering of twigs provides an important clue for more precise pruning practices: if in cultivars with prominent biennial flowering the twigs which have flowered are cut out after harvest (either all or some of them, depending on flowering intensity), canopy structure is simplified and largely limited to twigs which are more likely to flower next time. Flowering twigs which do not set fruit may be removed shortly after bloom. If this pruning method leads to better fruiting, both the pruning and the enhanced fruiting help to limit tree size.

Some 25 fungus diseases affect mango, the most serious and widespread disease being anthracnose (Glomerella cingulata, conidial stage Colletotrichum gloeosporioides). Anthracnose infects shoots, flowers and fruits; it is particularly ruinous if the trees flower under wet conditions. The dark-brown spots can develop at any time, on the fruit also after harvest from latent infections. Polyembryonic cultivars are generally less susceptible. Control with fungicides is possible, but may require up to 20 treatments per season. Other fungus diseases, not usually controlled in South-East Asia, are powdery mildew (which may cause substantial crop losses, as it infects flowers and fruitlets as well as the leaves), leaf spots and various storage rots of the fruit.
Malformation of inflorescences is a major cause of alarm in the subtropics. The disease, caused by Fusarium moniliforme var. subglutinans in conjunction with mites, apparently does not thrive in the warmer tropical climates. Affected parts are burned to contain the problem, but curative treatments, e.g. with the growth hormone naphtyl acetic acid and with mangiferin-chelates, are showing promise. There are also several bacterial diseases, of which bacterial black spot, caused by an Erwinia sp., is feared in Australia. So far there have been no reports of virus diseases in mango.
Mango hoppers can ruin even a heavy bloom and are the most important mango pest in South-East Asia. The hoppers are controlled by insecticides applied before bloom and at the beginning of a flush; the timing of the treatments is critical. A host of other pests can do serious damage, but these occur more incidentally: stem-, shoot- and twig-borers (the latter can also spoil bloom in a bad year), fruit-piercing moth, tent caterpillar or mango leaf-webber, mango weevil, flush caterpillar, leaf-cutting weevils and numerous sucking insects such as thrips, mealy bugs, aphids, scales, etc. Fruit- flies are feared because maggots in a few fruits can ruin the entire export business by putting off the consumers. Control rests on strict hygiene (making sure that maggots in infested fruit are destroyed by treating the fruit with hot water or burying it deep in the ground), bait sprays and bagging the fruit.

The fruit is picked by hand, either by climbing the tree or by using a picking bag with a cutting edge mounted on a bamboo pole. It is difficult to assess maturity from the appearance of the fruit. Mature-green fruit should have attained full size, the 'cheeks' should be well-developed and the endocarp should have hardened. There are more objective standards for major cultivars based on degrees Brix, specific gravity and firmness, but the simplest guide is number of days from full bloom or fruit set as established under an ASEAN research project.

From the statistics on area and production a mean annual yield of 6 t/ha in the Philippines, 3.5 t/ha in Peninsular Malaysia and 2.3 t/ha in Thailand can be calculated. These mean yields are quite low: for tropical high-quality cultivars 10 t/ha is considered a good annual yield. In the subtropics 10—30 t/ha is aimed at, depending on the cultivar (in particular its tendency to biennial bearing).

The fruit is perishable and as a rule marketed as quickly as possible. It is graded by size and the fruit stalk is trimmed so that it does not puncture other fruit. For the local market the mangoes are packed in bamboo baskets lined with some protective material. The fruit bruises easily and single-layer trays, preferably partitioned into single-fruit compartments, are used for the best quality fruit to the most discerning markets in Japan, the United States and Europe. Such fruit is washed and dipped in fungicide or hot water to control anthracnose; it is shipped by air.
To extend the short supply season, fruit can be eaten green, or be ripened artificially using, for instance, ethylene-releasing carbide (Indonesia). Cool storage can postpone ripening for up to one month; storage conditions depend very much on the cultivar.

The International Board for Plant Genetic Resources (IBPGR) promotes and coordinates germplasm collections in all important mango-growing countries; it lists 4743 accessions in 26 countries. All South-East Asian countries participate and extend and evaluate their own cultivar collections.

Little genetic information is available on mango. The main breeding objectives are dwarf tree size, good keeping and eating qualities, regular cropping, good cropping in the wet tropics, early or late season cropping, resistance to diseases (anthracnose) and pests (fruit flies). In South-East Asia improvements in mango production have resulted from selection within populations of polyembryonic seedlings. Programmes based on hybridization are being conducted.

The mango is the most important seasonal tropical fruit. However, mango is still a poorly understood crop. Large differences between cultivars and areas of production in the tropics and subtropics defy generalizations about tree phenology, fruitfulness, nutrient requirements, crop protection, etc.
In South-East Asia the need for improved post-harvest handling and marketing is often emphasized, but the low mean yield levels indicate that the greatest challenge is to improve fruitfulness. The change-over to commercial production in orchards, complemented by the emergence of nurseries which supply large quantities of uniform planting material, provides a favourable basis for a breakthrough in productivity.
Further progress should come from the study of the growth rhythm of leading cultivars in the centres of production. Such studies can reveal the correct timing of fertilization, crop protection measures and growth regulation in order to improve the quantity and quality of bloom. Detailed study of the growth rhythm at the twig level and of floral biology should give insight into the real constraints to fruitfulness, leading to well-defined pruning practices and — hopefully — to better pollination and fruit set.
Higher yield per tree reduces shoot growth, giving the grower a measure of control over tree size, a prerequisite for more intensive crop management. Development along these lines also holds promise for advancing the season of flowering and fruiting; in view of the short supply season, this is as important as a breakthrough in productivity. As shown in the Philippines, it drastically changes the prospects for marketing.
All the ingredients for the development outlined above are in fact available. The limited success in their application is largely due to one missing link: clarification of tree phenology, that is, the interaction of the crop growth rhythm with seasonal weather conditions, compounded by carry-over effects — e.g. biennial flowering and fruiting — from one year to the next.

Chadha, K.L., 1985. Mango cultivation. Extension Bulletin No 9. M/S Prithvvi Printers, Bangalore, India. 28 pp.
de Laroussilhe, F., 1980. Le manguier. Maisonneuve & Larose, Paris. 312 pp.
FAO, 1988. The world market for tropical horticultural products. FAO Commodities and Trade Division, Rome, Italy. pp. 5—6.
FAO, 1989. Selected indicators of food and agriculture development in the Asia Pacific Region, 1978—88. RAPA, FAO Bangkok, 1989/7: 78.
Lal Singh & Abdul Aziz Khan, 1939. Relation of growth to fruitbearing in mangoes. Indian Journal of Agricultural Science 9(6): 835—867.
Mendoza Jr., D.B. & Wills, R.B.H. (Editors), 1984. Mango: fruit development, post harvest physiology and marketing in ASEAN. ASEAN Food Handling Bureau, Kuala Lumpur, Malaysia. 111 pp.
Mukherjee, S.K., 1972. Origin of mango (Mangifera indica). Economic Botany 26: 260—264.
Singh, L.B., 1968 (reprint from 1960 edition). The mango. Botany, cultivation and utilization. Leonard Hill, London. 438 pp.
PCARRD, 1978. The Philippines recommends for mango. PCARRD Technical Bulletin Series No 38. 70 pp.
Whiley, A.W., 1984. Mango. In: Page, P.E. (Compiler): Tropical tree fruits for Australia. Queensland Department of Primary Industries, Information Series QI 83018, Brisbane. pp. 25—31.

Somchai Sukonthasing, Montri Wongrakpanich & E.W.M. Verheij

Sukonthasing, S., Wongrakpanich, M. & Verheij, E.W.M., 1991. Mangifera indica L.. In: Verheij, E.W.M. and Coronel, R.E. (Editors): Plant Resources of South-East Asia No 2: Edible fruits and nuts. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea