LITCHI OR LYCHEE
Litchi chinensis Sonn., family SapindaceaeThe litchi, or lychee, is grown for its agreeable sweet-acid tasting, white fleshy, juicy, translucent aril, or pulpy covering of its seed, which may be eaten fresh, canned in sirup, or dried to produce "litchi nuts."
The litchi was introduced into Florida in the 1880's but remained only a novelty until 1940 when an association of litchi growers was formed and some 250 to 300 acres were cultivated (Palmer 1956). Less than half that acreage exists now, due to urbanization and the occasional freezing weather that kills the plants. A few trees are grown in California.
Plant:
The plant is a dense, polygamous, oval evergreen tree, which grows to 30 feet high. It is widely scattered throughout the tropics but does well only at higher altitudes. It is propagated vegetatively, 20 to 50 trees per acre. It will grow about anywhere citrus will grow, but young plants are extremely sensitive to cold and require cold protection. The plants will produce as much as 10,000 pounds of fruit per acre. The fruit must ripen on the tree, then is harvested over a 6-week period. The shelf life of the fresh fruit is only 10 to 14 days (Palmer 19S6).
The round fruit, about the size of a large strawberry, is pendant in a loose cluster or panicle of several dozen fruits (Cobin 1952) (fig. 126). The leathery skin is covered with sharp-tipped tubercles and is usually red when ripe. The seeds are dark brown (Groff 1921).
The self-compatible 'Brewster' cv. comprises the bulk of the trees in Florida, but it is noted for being a light and irregular bearer. 'Mauritius' is a new and promising cultivar (Young 1966, Knight et al. 1968, Campbell and Malo 1968) but is not resistant to anthracnose.
The lychee tree lives for centuries. Banta (1952) reported that two trees in China are said to be 1,200 years old, the largest being 10.5 feet in diameter. Lychee thrives in the Florida citrus belt, but California's climate is generally too dry. Banta (1952) stated that a 4-year-old tree will produce 2 to 3 pounds of fruit, and a 12-year-old tree yielded 308 pounds.
[gfx] FIGURE 126. - Litchi tree with mature fruit.
Inflorescence:
The small (2 to 3 mm), greenish-yellow flowers are in terminal clusters, sometimes a foot long. They are present from mid-February through March. They have no petals, about eight stamens, a two-lobed stigma, an ovary on a short stalk, and one ovule in each of its two or three sections (Bailey 1949*). Grove (1951) stated that there are staminate and pistillate flowers. Butcher (1957a), however distinguished three types of flowers: Male or staminate flowers with no functional ovary, which appear first; female or functionally pistillate flowers with anthers that do not dehisce; and imperfect hermaphrodite flowers. Pollen produced on the last type is most viable (Mustard et al. 1953). In some years, certain cultivars produce only male flowers, and as a result no fruit sets. The reason for this is unknown but should be explored.
A nectary occurs on every flower as a large fleshy crenulate gland within a cup-shaped calyx and to which the stamens and pistils are inserted. Nectar is secreted only in the morning. The nectar is highly attractive to honey bees and flies. Lychee pollen seemed unattractive to wild bees in Florida (Butcher 1957a, Nakato 1956). When lychee' trees are plentiful, honey bees gather immense stores of high-quality honey (Groff 1943).
Khan (1929) cited two examples to show the floral variation on an individual panicle. On one plant, the panicle began flowering and for 10 days bore only male flowers. The next 11 days, the flowers were mixed (male or female). The remaining 6 days, only male flowers opened. Another panicle had male flowers for 13 days, mixed flowers for 2 days, all female for 2 days, mixed again for 3 days, and all male for the last 7 days. From 20 to 50 percent of all the flowers were functionally female.
The flowers open throughout the day but mostly before 6 a.m. Anther dehiscence also occurs more or less throughout the day and night, but it reaches its maximum around 10 a.m. Ultimate fruit set ranges from 2.8 to 8.2 fruits per panicle.
Pollination Requirements:
Mustard et al. ( 1953) concluded that shedding of fruit may be due to fertilization failure and embryo abortion. Chaturvedi (1965) reported 43 percent fertilized flowers on open pollinated branches, zero percent on branches bagged with muslin, and 15.5 percent on branches bagged under mosquito cloth. Das and Choudhury (1958) also reported no set of fruit on bagged panicles.
Pandey and Yadava (1970) reported that only 0.03 to 0.10 percent of flowers caged to exclude insects set fruit, whereas 0.7 to 11.2 percent (100 times as many) flowers exposed to insect pollination set fruit. Butcher (1957a, b) also reported that no fruit set on a tree caged to exclude insect pollination, proving that lychee plants require insect pollination. These tests supported Campbell and Malo (1968) by showing that the lychee is self-fruitful and that interplanting of compatible cultivars is unnecessary, but the pollen must be transported from anthers to stigmas for fruit set.
Pollinators:
Butcher (1957a, 1958) reported that in Florida the insect visitors to lychee flowers in order of numbers were: Calliphorid and screw-worm (Callitroga [=Cochliomyia] macellaria (Fab.)) flies and honey bees. No wild bees were seen on the plant although they were present on other flora. Pandey and Yadava (1970) reported that in India Apis spp. and Melipona spp. comprised 98 to 99 percent of the total visitors. Chaturvedi (1966) mentioned honey bees, flies, ants, and wasps as floral visitors. Groff ( 1943) considered bees the most outstanding beneficial insects on lychee. Butcher (1957a) concluded that the value of the honey bee was obvious in the setting of lychee fruit. Das and Choudhury (1958) stated that the chief pollinators were bees, other Hymenoptera, and flies.
Pollination Recommendations and Practices:
Although no specific number of colonies per unit of lychee has been recommended, Butcher (1957a, 1958) stated that supplying honey bees to lychee plantings is an important and practical recommendation for assuring adequate pollination and fruit-setting. He further felt that the bees should be present continuously throughout bloom. The degree to which growers go to in the use of bees has not been recorded.
LITERATURE CITED:
BANTA E. S.
1952. BEHOLD! THE LYCHEE. Amer. Fruit Grower 72(10): 10-11, 20-21.BUTCHER, F. G.
1957a. POLLINATING INSECTS ON LYCHEE BLOSSOMS. Fla. State Hort. Soc. Proc. 70: 326-328.____ 1957b. BEES POLLINATE LYCHEE BLOOMS. Fla. Lychee Growers Assoc. 1956 Yearbook and Proc. 3: 59-60.
____ 1958. POLLINATING INSECTS ON LYCHEE BLOSSOMS. Fla. Lychee Growers Assoc. 1957 Yearbook and Proc. 4: 39-41.
CAMPBELL C. W., and MALO, S. E.
1968 THE LYCHEE. Fla. Agr. Ext. Serv. Fruit Crops Fact Sheet 6. 2 pp.CHATURVEDI, R. B.
1965. PRELIMINARY STUDIES IN THE SEX DISTRIBUTION, POLLINATION AND FRUIT DEVELOPMENT IN LITCHI (LITCHI CHINENSIS SONN.). Allahabad Farmer 39(2): 49-5LCOBIN, M.
1952. THE LYCHEE IN FLORIDA. Fruit Varieties and Hort. Digest 6: 52-53.DAS, C. S., and CHOUDHURY, R.
1958. FLORAL BIOLOGY OF LITCHI (LITCHI CHINENSIS SONN.). So. Indian Hort. 6(1): 17-22.GROFF, G. W.
1921. THE LYCHEE AND LONGAN. 188 pp. Orange-Judd Publishing Co., New York.____ 1943. SOME ECOLOGICAL FACTORS INVOLVED IN SUCCESSFUL LYCHEE CULTURE. Fla. State Hort. Soc. Proc. 56: i34-155.
GROVE, W. R.
1951. THE LYCHEE IN FLORIDA. Fla Dept. Agr. Bul. (n.s.) 134, 15 pp.KHAN KHAN SAHEB ABDUR RAHMAN.
1929. POLLINATION AND FRUIT FORMATION IN LITCHI. Agr. Jour. lndia 24: 183-187.KNIGHT, R. J., JR., MANIS, W. E., KOSEL, G. W., and WHITE, C. A.
1968. EVALUATION OF LONGAN AND LYCHEE INTRODUCTIONS. Fla. State Hort. Soc. Proc. 81: 314-318.MUSTARD, M. J., SU-YING, LIU, and NELSON, R. O.
1953. OBSERVATIONS OF FLORAL BIOLOGY AND FRUIT-SETTING IN LYCHEE VARIETIES. Fla. State Hort. Soc. Proc. 66: 212 - 220.NAKATA, S.
1956. LYCHEE FLOWERING AND GIRDLING. Hawaii Farm Sci. 4(3): 4-5.PALMER, G.
1956. SOME ASPECTS OF THE LYCHEE AS A COMMERCIAL CROP. Fla. State Hort. Soc. Proc. 69: 308.PANDEY, R. S., and YADAVA, R. P. S.
1970. POLLINATION OF LITCHI (LITCHI CHINENSIS) BY INSECTS WITH SPECIAL REFERENCE TO HONEYBEES. Jour. Apic. Res. 9(2): 103-105.YOUNG, T. W.
1966. A REWEW OF THE FLORIDA LYCHEE INDUSTRY. Fla. State Hort. Soc. Proc. 79: 395-398.