Camellia sinensis (L.) Kuntze
Family
Camelliaceae
Synonyms
Thea sinensis L., Camellia thea Link, Camellia theifera Griff.
Vernacular Names
| English | Tea. |
| Indonesia and Malaysia | Teh. |
| Philippines | Tsa (Tagalog). |
| Burma (Myanmar) | Leppet. |
| Cambodia | taè. |
| Laos | s’a:, hmièngx. |
| Thailand | Cha (Central), Miang (Northern). |
| Vietnam | ch[ef], tr[af]. |
| French | Théier (plant), thé (product). |
Geographical Distributions
The natural habitat of C. sinensis is the lower montane forest on mainland Asia from south-western China (Sichuan) to north-eastern India (Assam). The primary centre of origin is presumed to be near the source of the Irrawadi (Ayeyawadi) river in northern Burma (Myanmar), but early human interest in the stimulating properties of tea may have been instrumental in its wider dispersal in Asia. The tea plant was already known to the Chinese peoples more than 4000 years ago. Written records dating from the 5th Century AD confirm its widespread cultivation and general use as a refreshing beverage in several Chinese provinces. Tea cultivation in Japan was started in the 9th Century with seed introduced from China. Tea became an important export commodity for China, first through the Mongols by old overland trading routes in central Asia to Turkey and Russia (mainly as brick tea), and then from the early years of the 17th Century also to Europe by sea, through the Dutch and English East India Companies (green, and later black tea). For more than 300 years all the tea drunk in the Western world came from China (100 000 t in 1850), but this monopoly on the international tea market gradually came to an end with the development of tea plantations in India (1840), Sri Lanka (1870) and Indonesia (1880). By 1925 very little of the 300 000 of tea imported into Europe came from China. Tea exports from China were resumed in quantity in the 1960s.
The tea grown in China and Japan is all C. sinensis var. sinensis (‘China tea’), which has smaller leaves and more cold tolerance but grows less vigorously than C. sinensis var. assamica (Mast.) Kitamura (‘Assam tea’) discovered in the forests of north-eastern India in 1823. Assam tea and subsequently hybrids between the two varieties (‘Indian hybrid tea’) became the basis for the tea industries of South, Southeast and West Asia, as well as for those established in Africa and South America. In Southeast Asia, tea cultivation is most important in Indonesia, Vietnam, Papua New Guinea, Malaysia and Thailand.
Description
Camellia sinensis is an evergreen, multi-stemmed shrub which can grow measuring up to 3 m tall (var. sinensis), or tree up to measure 10-15 m tall with one main stem (var. assamica). In cultivation it is pruned to measure about 1-1.5 m and trained as a low profusely branching and spreading bush. The strong taproot and many lateral roots rise to a dense mat of feeding roots in the top 50-75 cm of the soil. Some lateral roots grow 3-4 m deep. The feeding roots are in association with endotrophic mycorrhiza while the root hairs lack. The branchlets are finely pubescent at the apex.
The leaves are arranged alternate and with short petiole. The blade is obovate-lance-shaped, measuring 4-30 cm x 1.5-10 cm, serrate, obtuse with broad cusp to acuminate, slightly pubescent on the lower surface when young, stomata on the lower surface only, characteristic sclereids (stone cells) in mesophyll and calcium oxalate crystals in phloem of petiole. In var. sinensis the blade is leathery and usually stiff-erect, narrow and usually less than 10 cm long. It is dark green with dull, flat surface and indistinct marginal veins while in var. assamica it is thinly leathery and horizontal or pendant, wider and longer (15-20 cm long), lighter green with glossy, blistered upper surface and distinct marginal veins.
The flowers are axillary, single or in clusters measure of 2-4, 2.5-4 cm in diametre and very fragrant. The pedicel is short. The sepals are 5-7 and persistent. The petals are 5-7, obovate, concave in shape, white or light pink in colour and slightly coherent at the base. The stamens are 100-300 and with 2-celled yellow anthers. The outer filaments are fused at the base and coherent with petals while the inner ones are free. The pistil is with 3—5-loculed superior ovary, 4-6 ovules per carpel, and 3-5 free (var. sinensis) or partly fused (var. assamica) styles with stigmatic lobes.
The fruit is a nearly spherical capsule, measuring 1.5-2 cm in diametre, thick-walled and woody. It is brownish-green, usually 3-lobed and 3-loculed and with 1-2 seeds per locule.
The seed is spherical or flattened on one side, measuring 1-1.5 cm in diametre, light brown testa (shell) and hard and integument thin papery. The endosperm is absent. The cotyledons are thick and rich in oil while embryo is straight.
The seedling is with epigeal germination.
Ecology / Cultivation
C. sinensis originated from an area of monsoon climates (warm, wet summers and cool, dry winters) but is presently grown in a range varying from Mediterranean to tropical climates, between 42°N (Georgia) and 27°S (Argentina) latitudes, as well as from sea-level to 2300 m altitude.; Mean annual rainfall varies from 1500 mm (Uganda) to 3500 mm (West Java). About 1700 mm annual rainfall is the minimum requirement for economic tea production. Additional irrigation is only effective under sufficiently high air humidity. On the other hand, rainfall of 5000 mm has no adverse effect on tea growth. Rainfall should not fall below 50 mm per month for any prolonged period. Hail can be a serious hazard to tea, causing yield losses of 10-30% in some areas (e.g. in Kenya above 2000 m altitude). Generally, optimum temperatures for shoot growth are between 18-30°C. The base temperature (Tb), below which shoot growth stops, is about 12.5°C, but this can vary between genotypes from 8-15°C. The thermal time – i.e. the product of number of days and effective temperatures (T – Tb) – for the SRC in tea is on average 475 day, in the absence of water stress. It has been shown to be a very useful parameter to estimate seasonal and geographical effects of temperature on the length of the SRC and consequent yield patterns. At average daily temperatures of 22.5°C the SRC would thus be 48 days against 79 days at 18.5°C. The thermal time parameter is not applicable at temperatures above 30°C, as the co-occurring high vapour pressure deficits of the air (> 23 mbar) depress shoot growth. Tea is not killed by the night frost that occurs in important tea-growing areas at higher latitudes. China-type teas are more tolerant of colder climates. Daylength does not have a large influence on seasonal variation in growth (yield) or flowering.
At high altitudes in tropical areas the photosynthesis of whole canopies of the tea crop becomes saturated at 75% of full sunlight. Tea is generally more productive without shade, but shade trees may be necessary to reduce air temperatures during hot periods, e.g. in Assam and Bangladesh. Shelter belts of trees planted between fields are beneficial in protecting tea against prevailing strong winds.
Tea is grown successfully in a wide range of soil types developed from diverse parent rock material under high rainfall conditions. Soils suitable for tea cultivation should be free-draining, have a depth of 2 m, a pH between 4.5 and 5.6, a texture of sandy loam to clay and good water-holding capacity.
Climatic conditions have a great influence on the quality of the tea, especially on the flavour. Fast shoot growth — for instance at low altitudes, during the best part of the growing season or shortly after the bushes have been pruned back — is detrimental to the quality of tea, particularly the flavour, but induces high production. Hence, both in respect of plucking method and inputs to encourage growth (e.g. heavy manuring) the grower has to choose between high yield and good quality. Nevertheless, high yields and excellent quality tea can be obtained in tropical countries on fertile soils, especially at elevations of 1200—1800 m above sea-level. At still higher elevations, the tea will have a well-developed flavour but it will lack strength and yields will be lower. Likewise, the retarded shoot growth during a dry period and the proliferation of growing points with an attendant reduction in shoot vigour shortly before the next pruning round result in better flavour but low yields.
Line Drawing / Photograph
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References
- Plant Resources of South-East Asia No. 16: Stimulants.
