Eriobotrya japonica (PROSEA)
Eriobotrya japonica (Thunb.) Lindley
- Protologue: Trans. Linn. Soc. London 13: 102 (1821).
- Family: Rosaceae
- Chromosome number: 2n= 34
- Loquat (En)
- Néflier du Japon (Fr)
- Indonesia: lokwat, papalaan (Sundanese)
- Malaysia: lokwat, paginggong (Peninsular)
- Cambodia: tôn leap
- Thailand: lokhwot, pipae (central)
- Vietnam: sơn trà nhật bản, ti bà diệp, nhót tây
Origin and geographic distribution
Loquat most probably originated in south-eastern China and has been cultivated there and in Japan since antiquity. It is now found throughout the subtropics and tropics and grown commercially not only in China and Japan, but also in the Mediterranean region, Australia, South Africa, South America, California (United States) and India. In South-East Asia it is only grown in home gardens at higher altitudes, at least in Peninsular Malaysia, Java and the Philippines.
The sweet-sour juicy fruit is eaten fresh or preserved as jam or jelly. The seeds are used to flavour (almond-like taste) drinks and cakes. The juice can be used to prepare an alcoholic drink. In the Kilimanjaro region of East Africa the tree is commonly grown on the borders of the home compounds and lopped to provide fodder for goats. The wood of the tree is in demand to make stringed music instruments. The tanniferous leaves are astringent and antidiarrhoeic and in China used to heal wounds; the flowers are used as expectorant, as insect repellent and, extracted in oil, in cosmetics; the fruit is considered to be sedative and used in allaying vomiting and thirst. Loquat is also grown as an ornamental tree.
Production and international trade
Loquats are produced in quantity in China but no data on area or production are available. Japan, one of the major producers, reports annual crops ranging from 17 400 to 7000 t over the years 1972-1977, on an area of 2350 ha (10% of which carried immature trees). Small quantities of fruit enter international trade, demand being supported by the fact that loquat is the first fruit to ripen in spring. In tropical areas loquat also tends to ripen outside the main fruit season.
The fruit consists of 60-70% pulp, 15-20% seed, 15-20% skin and core. Per 100 g edible portion the fruit contains: water 85 g, protein 0.4 g, fat 0.05 g, carbohydrates 10 g, fibre 0.9 g. The potassium content is rather high, the sodium content quite low. The fruit is low in vitamin C but some cultivars are a good source of vitamin A. The fruits are a good source of acid and pectin.
- Evergreen shrub or small tree, 5-10 m tall, with a straight low-branched trunk, a dense rounded crown and rusty-tomentose branchlets.
- Leaves alternate, oblong-lanceolate, 12-30 cm × 3-8 cm, remotely dentate, dark glossy green above, rusty tomentose beneath, stiff, with prominent lateral veins that run to sharp teeth on the wavy margins; petiole up to 5 mm long, stipules subulate, persistent.
- Inflorescences in panicles, 10-20 cm long, 80-150-flowered, rusty pubescent; flowers sessile, 15-20 mm in diameter, fragrant; calyx lobes 5, ovate, densely woolly, persistent on top of the fruit; petals 5, obovate, white to creamy; stamens ca. 20, styles 2-5, ovary inferior, 2-5-celled.
- Fruit a globose or ovoid pome, 3-8 cm × 2-5 cm, pale yellow to deep orange, densely pubescent; pericarp fleshy.
- Seeds 1-5, ca. 2 cm long, dark brown.
When grown from seed the trees take 6-8 years to bear fruit, but frequent flushing may halve this period in the tropics. Leaves on juvenile trees are large, flat and thin, but during the season preceding flowering new leaves are narrower and stiff, remaining bowed like a boat.
The growth rhythm of loquat is peculiar in the sense that in their natural environment the trees flower as winter approaches (October-November in northern Vietnam and Thailand). Flowering is protracted because of the falling temperature and may continue for several months in the subtropics, but fruit sets over only a fraction of that period. The fruit ripens in early spring. The period from anthesis to harvest depends on the prevailing temperature, but 3 months is normal. During a post-harvest flush the terminal buds are formed. Tree vigour should be moderate so as not to interfere with floral differentiation of these buds. Subsequently, the floral buds should remain quiescent until winter approaches.
Continued flushing and any flowering during summer are detrimental for prolific bloom in the autumn or early winter. Moreover, out-of-season flowers do not set fruit as a rule. This is the major problem in tropical highlands where favourable growing conditions prevail almost throughout the year, leading to excessive, asynchronous flushing, untimely flowering and negligible crops.
As the tree matures, inflorescences are increasingly borne on spurs formed through sympodial and plagiotropic branch extension (Fagerlind's architectural model). Fruit set is better on these spurs than on long shoots; it is said that 7 or more subtending leaves are needed for strong inflorescences and good fruit set. Several cultivars are self-incompatible and cross-pollination (by bees, flies) is recommended.
Many loquat cultivars exist. Based on origin, two groups are distinguished: the Chinese group with large, pyriform, deep orange fruit, ripening mid-season to late, which can be kept for a week or two, and the Japanese group with small, slender, light-coloured fruit, maturing early and having a shorter shelf life. The first group includes the cultivars "Tanaka", "Thales" and "Tsirifin 8"; examples of the second group are "Advance" (though ripening late), "Acco 13" (the leading cultivar in Israel) and "Mogi" (Japan's major cultivar).
Loquat's ecology is unusual as the natural cropping season is the winter period and summer is the season of rest. Hence mild, humid winters are necessary, although flowers and fruits can stand light frost and the tree survives temperatures as low as -10°C. Where insolation is strong the fruit clusters are bagged to prevent sunburn (purple stains on the fruit in Brazil). On the other hand the fruit remains sour where sunshine is lacking (northern Tanzania). There should be sufficient moisture for a good post-harvest flush, but thereafter limiting factors (low moisture and nutrient levels, competition from a cover crop) should impose quiescence until the time has come for the flush that carries the flowers for the next crop. It is not known what triggers bloom at the right time, but it seems likely that progressive leaf fall during the quiescent period plays an important role. Suitable seasons with mild humid conditions are generally found in tropical highlands at elevations of 700-2000 m. Loquat grows well in these highlands, in fact often too well, leading to poor flowering and fruiting. It is not clear what distinguishes the highlands where the crop is grown successfully; even in the prominent monsoon climate of East Java the growth rhythm tends to become asynchronous.
Loquats grow well in a wide range of soils, preferring acid over alkaline soils; growth is poor in saline soils. The trees require good drainage and protection from the sun for the surface roots. The trees are sometimes planted to mark the borders of fields, but sheltered locations are important for fruit production.
Since seedlings generally yield inferior fruit, loquat is propagated by air layering, budding (shield budding) or grafting (in particular, side veneer grafting). Wood for budding and grafting should be mature (3 months old) and loquat seedlings are used as rootstock. Quince (Cydonia oblonga P. Miller) is recommended as a dwarfing rootstock, but was not successfully used in India, possibly because dwarf trees require rather intensive husbandry. Grafting on apple, pear and medlar (Mespilus sp.) is also possible. Trees are spaced 6-8 m apart, but closer spacing seems possible and dwarf trees in Israel have been planted at 4 m × 2 m.
Cloned trees flower readily within one or two years, but worthwhile fruit set takes a few more years. The young tree is pruned to obtain an unbranched trunk of 50 cm or more. Later, pruning is limited to some thinning of branches in the tree centre and removal of ageing, sagging branches.
Irrigation may be needed from budbreak before bloom and moisture stress should be avoided until harvest, to obtain large fruit and a good post-harvest flush. Thereafter lower moisture levels suffice, but undue loss of leaves should be prevented as this might trigger a flush following replenishment through rain or irrigation. Orchards are normally clean-cultivated, but a cover crop established as the fruit is ripening may be useful to impose quiescence; it could be incorporated as green manure or applied as mulch under the trees when bloom is imminent. Manures or fertilizers should generally be supplied at this time too, to amplify the contrast between fruiting season and rest season. Fruit thinning by cutting terminal parts of the cluster helps to improve fruit size and quality.
The fruit clusters are sometimes bagged to prevent sunburn and damage from fruit flies and birds. The loquat is relatively free from other pests though sucking insects and a bark-eating caterpillar may need to be controlled. Diseases are also few, collar rot caused by Diplodia natalensis being worth mentioning; it attacks the bark and may eventually kill the tree.
Figures for yield per tree vary from 16-20 kg to occasional yields of more than 100 kg. Mean yield in Japan over 1972-1977 amounted to 7.6 t/ha. The highest yield record is for an orchard of dwarf trees in Israel, yielding 25 t/ha in the 7th year. Although the fruit is delicate, it ships better than most tropical fruits. Cultivars of the Chinese group can be stored for a few weeks.
Genetic resources and breeding
The Horticultural Research Institute, Saharanpur, India, holds a germplasm collection of loquat. Breeding focuses on high yield, improving storage quality, taste, size and flavour of the fruit. About 30 Eriobotrya spp. occur in Asia. It is not known whether they hold promise for the improvement of loquat; E. bengalensis (Roxb.) Hook.f., with a wide distribution in South-East Asia, is the closest relative and possible progenitor.
The views presented on growth and development in relation to the ecology and the implications for husbandry are based on piecemeal information; the resulting growth model needs to be checked in the field. Loquat appears to be more productive in the subtropics than in the tropics. The short period from anthesis to harvest and the ease with which out-of-season flowering occurs in the tropics, suggest that it might be possible to manipulate the trees to produce 2 crops per year as is done with apples in East Java. This would turn the handicap of the tropical highlands - continuously favourable growing conditions - into an advantage.
- Endat Hidajat, 1979. Papalaan (Eriobotrya japonica Lindl.) [Loquat]. Buletin Kebun Raya 4(3): 93-95.
- Pathak, R.K. & Hari Om Gautam, 1985. Loquat. In: Bose, T.K. (Editor): Fruits of India. Tropical and Subtropical. Naya Prokash, Calcutta, India. Chapter 23: 548-558.
- Rivals, P. & Assaf, R., 1977. Modalités de croissance et systèmes de reproduction du néflier du Japon (Eriobotrya japonica Lindl.). Fruits 32: 105-115.
- Sawyer, P., Houghton, P. & Manuel L., 1985. Loquats: a literature search. California Rare Fruit Growers Yearbook 17: 23-33.
Nguyen Tien Hiep & E.W.M. Verheij