Chapter 9: Crop Plants and Exotic Plants

TEA
Camellia sinensis (L.) O. kuntze, family Theaceae
Tea is an evergreen shrub widely cultivated throughout the tropics and subtropics especially in hilly or mountainous regions for its tender leaves that are dried and used for a mildly stimulating beverage. Asia produces more than a billion pounds annually; Africa, more than 200 million pounds; and South America, more than 26 million pounds. We import about 140 million pounds from Africa, 100 million pounds from Asia, and 3 million pounds from South America (Purseglove 1968*). Harler (1969) stated that about 970 pounds per acre were produced in northeastern India.

Tea growing was tried in South Carolina over a century ago on about 300 acres, and, even though it grew well, its production was not economical so it was discontinued (Mitchell 1907).

Plant:
Tea prospers in areas with a moderate temperature, high humidity, and moderate to high rainfall. It is killed by frost. Under cultivation, it is usually kept pruned to a spreading shrub 2 to 5 feet in height, with about 2,000 plants per acre. A plant may live 40 to 100 years, its shoots (the bud and two tender leaves) can be plucked each 7 to 14 days, 4 pounds of which yield 1 pound of dried or "made" tea. Mature plants annually yield about 1,000 pounds of made tea per acre.

The fruit is a thick-walled, brownish-green, three-lobed, and usually three-celled capsule, 3/4 to 1 inch in diameter. Upon maturity, 9 to 12 months after flowering, it splits from the apex to release the 1- to 11/2-cm long seeds.

Tea is planted from seed, the estimated acreage planted annually ranging from 20,000 to 50,000 acres. Planting is at the rate of about 40 pounds of seed per acre. When seed is produced commercially, only 70 to 100 trees per acre are maintained instead of the 2,000 used for production of leaves. Production of 1,000 pounds seed per acre is considered a conservative estimate. This means that annually from 800 to 2,000 acres must be devoted to production of seed.

Inflorescence:
The fragrant flowers, 2.5 to 4.0 cm in length, are axillary, solitary, or in clusters of two to four flowers. They have five to seven white or pink-tinged petals, numerous 1/2-inch-long stamens, with three to five stigmatic lobes of the style about level with the anthers. According to Free (1970*), the flower opens in the afternoon and remains open for 2 days.

Pollination Requirements:
The flowers are pollinated by insects. Tea is virtually self-sterile and almost entirely cross-pollinated (Purseglove 1968*, Wight and Barua 1939, Wu 1967). Kutubidze (1958) reported that supplementary pollination produced more, larger, and heavier capsules, better viability, and a higher grade of seed. Simura and Oosone (1956), in studying the embryology of the tea plant, noted that, as in many other plants, self-pollen grows much more slowly in the style than foreign pollen. Tomo et al. (1956) also concluded that tea was highly self-incompatible, largely due to inhibition of pollen tube growth at the tip of the ovary. Kutubidze (1958) noticed that supplementary pollination of hybrid and commercial strains by mixed pollen of other plants of the same strain increased set of fruit and size of capsule. Bakhtadze (1932) reported that isolated plants had an 85- to 95- percent reduction in seed set. Self-pollination did not help to increase set, and, furthermore, only 34-percent germination resulted from selfed seed, whereas crossed seed had 75-percent germination. A greater percentage of the crossed seeds developed into plants that reached maturity, and these plants were more vigorous than the selfed plants. Harler (1964) stated that only about 2 percent of the tea flowers on a tree produced seed, although by artificial pollination this can be raised to 14 percent. He concluded that, to get even 2 percent, at least nine random trees are needed for cross-pollination. Pollinating agents were not mentioned.

Bakhtadze (1932) stated that bees are the chief pollinating agents of tea, but that there were not enough bees present in his area to effect complete pollination of all the flowers. He made no mention of bringing in pollinators to the crop. Kutubidze (1964) recommended that steps be taken to obtain additional cross-pollination for increasing yield and quality of tea.

Pollination Recommendations and Practices:
None, although the evidence is sufficiently strong to recommend the building up of pollinators in tea seed fields.

LITERATURE CITED:
BAKHTADZE, K.
1932. POLLINATION OF TEA, CAMELIA SINENSIS, IN GEORGIA. Subtropics 2(12): 63-80.

HARBER, C. R.
1964. THE CULTURE AND MARKETING OF TEA. 262 pp. Oxford University Press, London.

______ 1969. UNPRUNED TEA IN UPPER ASSAM. Investors' Guardian 213: 1020-1022.

KUTUBIDZE, V. V.
1958. [INTRAVARIETAL SUPPLEMENTARY POLLINATION OF THE TEA PLANT WITH A POLLEN MIXTURE.] Agrobiologiya 4: 53-56. [In Russian.] Abstract in Plant Breeding Abs. 29(4): No. 4254, p. 835, 1959.

______ 1964. [METHODS OF THE PRODUCTION OF TEA HYBRID SEEDS, THE INCREASE OF ITS YIELD AND THE IMPROVEMENT OF ITS QUALITY.] Makharadze. Vses. Nauch.-Issled. lnst. Chaya. [ Subtropical Crops. ] 4: 39-42. [In Russian, English summary.]

MITCHELL, G. E.
1901. HOME-GROWN TEA. U.S. Dept. Agr. Farmers' Bul. 301, 16 pp.

SIMURA, T., and OOSONE, K.
1956. [STUDIES ON THE FERTILIZATION OF THE TEA PLANT.] Ikushugaku Zasshi-Jap. Jour. Breeding 6: 11-14. [In Japanese, English abstract.]

TOMO N., FUCHINOUE Y., and FUCHINOUE, H.
1956. [STUDIES ON SELF-FERTILIZATION OF THE TEA PLANT.] Chagyo Kenkyu Hokoku-Tea Res. Jour. 7: 14-20 [In Japanese, English Abstract.]

WIGHT, W., and BARUA, P. K.
1939. THE TEA PLANT INDUSTRY, SOME GENERAL PRINCIPLES. Indian Tea Assoc. Tocklai Expt. Sta. Memo. 7, 13 pp.

WU, C. T.
1967. [STUDIES ON THE PERCENTAGES OF FRUIT-SETTING OF SELF- AND CROSS-POLLINATION AND ITS RELATION TO SOME ECONOMIC CHARACTERS OF THE F₁ HYBRIDS IN TEA PLANT Agr. Assoc. China, Jour. 59: 24-39. [In Chinese, English summary.]