Banana

Plant

Plants are large, herbaceous monocots, reaching 25 ft in some cultivars. The "trunk" or pseudostem is not a true stem, but only the clustered, cylindrical aggregation of leaf stalk bases. Leaves are among the largest of all plants, becoming up to 9 ft long and 2 ft wide. There are 5-15 leaves on each plant. The perennial portion of the plant is the corm which may weigh several kilograms. It produces suckers, which are thinned to 2-3 per corm - one "parent" sucker for fruiting and one "follower" to take the place of the parent after it fruits and dies back. The vegetative apex spontaneously initiates a reproductive meristem after 40 leaves have been produced, usually 9 months after initiation of a sucker.

A banana plant bears fruit 10-12 months after planting; plantains take longer, 14-19 months, particularly in areas with cool winters. The life of a banana plantation is 25 years or longer, but individual "stools" are removed after production declines in 4-5 yr, which helps to control diseases as well. Fields are cleared, sometimes fumigated, then replanted with "bits" of new corms.

Flowers

The inflorescence is a spike originating from the tip of the corm. Initially, it appears above the last leaves in an upright position, and consists only of a large, purple, tapered bud. As this bud opens, the slim, white, tubular, toothed flowers are revealed, clustered in whorled double rows along the stalk, each cluster covered by a thick, waxy, hood-like bract. The bract lifts from the first hands in 3-10 days. Female flowers, with inferior ovaries, occupy the lower 5 to 15 rows on the stalk, with neuter or hermaphrodite flowers in the center, and males at the top. Male flowers and bracts are shed one day after opening, leaving the terminal potion of the stalk naked except for the large, purple, fleshy bud at the tip containing unopened male flowers (except Dwarf Cavendish - males persistent). The flower stalk begins to droop down under its own weight shortly after opening; the flowers are negatively geotropic, and turn upright during the first 10 weeks of growth.

Pollination

Bananas of the Cavendish group are triploids, and therefore completely sterile; fruit is set parthenocarpically. Traces of the undeveloped ovules are seen as brown specs in the center of the fruit. Floral morphology suggests that wild bananas are bat pollinated in their native range.

Fruit

An epigynous berry, fruit are borne in "hands" of up to 20 fruit, with 5-13 hands per spike. Fruit appear as angled, slender, green "fingers" during growth, reaching harvest maturity in 90-120 days after flower opening. The large, fleshy, terminal bud on the stalk may be removed if fruit set is high, to allow more complete filling of fruits (thinning) since this organ continues to grow throughout fruit development.

'Giant Cavendish' bunch = 110 lbs @ 363 marketable fruits.
'Gros Michel' - produces 3-7 tons/acre/yr in Central America.
'Maricongo' - high density plantings (5x5 ft) produce 13 tons/acre/yr.

Soils and climate

Soils: Deep, well-drained alluvial soils are best, but bananas can tolerate a wide variety of soil conditions. Bananas require heavy fertilization for adequate yield - 200-300 lbs N/acre and up to 500-600 lbs K/acre are used.

Climate: The banana is adapted to hot, wet, tropical lowlands. However, in South and East Africa, banana cultivation may extend to 5000 ft above sea level. Mean temperature should be 80 F, and about 4 inches rain/month are required, with dry seasons no longer than 3 months. Frost kills plants to the ground, although the corm usually survives.

Propagation

New banana stools are established using corms or pieces of corms called "bits" or "eyes". In the absence of bits, suckers from existing stools may be removed and planted. B. Propagation. New banana stools are established using corms or pieces of corms called "bits" or "eyes". In the absence of bits, suckers from existing stools may be removed and planted.

Planting design, pruning, training

Design: Spacing between plants varies proportionally to cultivar height at maturity, but generally 400-800 plants/acre are used. Common spacings range from 6x10 to 12x15 ft.

Pruning & training: Stools are allowed to produce only 2-3 pseudostems at a time - one larger, fruiting stem, and another smaller sucker that will produce fruit 6-8 months after the main stem is harvested.

Backyard considerations. 

Banana fruits are sensitive to chilling temperatures ( 50 F), and cannot be produced outside the tropics commercially. However, banana plants may be grown in the southeast as ornamentals, provided they are protected from freezing. Fruiting is an extremely rare occurrence, even in northern Florida, unless corms are overwintered properly and get a head start on growth in spring. Dwarf types may be grown in tubs and moved indoors during the winter, provided there is a sunny window. I fruited ‘Raja Puri' bananas in Savannah in 1998! ..this is a fast maturing, dwarf type plant with purple mottled leaves. Corms were set in February, killed back in a March freeze, but grew to 6-8 ft and had bunches of fruit by November. Of course, the Fall of 1998 was unusually warm.

Maturity

Fruits can be harvested when about 75% mature, as angles are becoming less prominent and fruits on upper hands are light-green in color. At this stage, desiccated styles on tips of fruit can be easily rubbed off. This occurs at 75-80 days after opening of the first hand. Some managers manipulate the harvest date as per the direction of the buyer, and harvest may be delayed up to 100-110 days after opening of the first hand.

Harvest method

Entire spikes are cut from pseudostems by hand with sharp, curved knives. The cutter leaves a portion of bare stalk as a handle for transporting to the packinghouse.

Post-harvest handling, packing

Bananas are carried by hand to a packing shed, or in large plantations, hung on tramways and pulled out of plantings by tractors; this expedites the process and limits handling. Bananas should be kept out of light after harvest, since this hastens ripening and softening. For local consumption, hands are often left on stalks and sold to vendors who cut hands/fingers to customer's order. For export, hands are cut into units of 4-16 fingers, graded for both length and width, and carefully placed in poly-lined 40 lb boxes. Prior to packaging, fruits are sometimes floated in water or dilute sodium hypochlorite solution to remove latex which may cause black peel staining. Fruit are shipped by boat when green, and ripened by exposure to ethylene gas (1000 ppm for 24 hr) at their destination, in sealed "banana ripening rooms".

Storage

fruit can be stored for a short time after ripening at temperatures no lower than 55 F, since fruit are susceptible to chilling injury.

Other than fresh consumption, bananas & plantains are used for:

1. Banana puree - baby food, cake, pie, ice cream, doughnuts, etc.
2. Banana/plantain flour - from sun-dried fruits, used for pastries; sometimes mixed with cassava flour.
3. Cooking - plantains are often fried in fat, and eaten like french fries. Mofongo is fried green plantain mixed with pork and seasoned.
4. Dried fruit - are sliced thin and sold as chips, or larger and more moist sections as "banana figs".
5. Fermented bananas -made into beer and wine in Africa.
6. The terminal male bud can be boiled and eaten as a vegetable.
7. New shoots are collected and eaten as greens.