General Information and Agronomic Aspects
Bananas are perennial tropical plants whose fruits are used both for cooking (plantains) and as table fruits. They may also be processed into starch, chips, puree, beer (in Africa), vinegar, or may be dehydrated and sold as dried fruit. Flour is produced from both plantains and table bananas, which can then be used in soups, baking or as a drink.
The flowers can be used as a vegetable, but they have to be heated briefly in salty water to remove the bitterness. The fresh leaves have a high content of protein and cattle and chicken like them because of their taste. The leaves are also used as packing material and for roofing. Together with the stem (pseudo-stem) it also offers an excellent mulching material. Bananas can also be planted as a windbreak to a vegetable garden.
Bananas are a staple food in many of the lower altitude, wetter areas of East Africa. They are mostly grown as a subsistence crop, although there is much internal and regional trading.
Nutritive Value per 100 g of edible Portion
|Raw or Cooked Banana||Food|
(Calories / %Daily Value*)
(g / %DV)
(g / %DV)
(g / %DV)
(mg / %DV)
(mg / %DV)
(mg / %DV)
|Vitamin B 6|
|Vitamin B 12|
(mg / %DV)
(mg / %DV)
(g / %DV)
|Banana raw||89.0 / 4%||22.8 / 8%||0.3 / 1%||1.1 / 2%||5.0 / 1%||22.0 / 2%||0.3 / 1%||358 / 10%||64.0 IU / 1%||8.7 / 15%||0.4 / 18%||0.0 / 0%||0.0 / 2%||0.1 / 4%||0.8|
*Percent Daily Values (DV) are based on a 2000 calorie diet. Your daily values may be higher or lower, depending on your calorie needs.
Climatic conditions, soil and water management
The ancestors of the commercial bananas originated from the Malaysian Peninsula, New Guinea and South-East Asia. They grow in alluvial and volcanic soils, as well as in river deltas and forest perimeters, where the soil is rich in organic matter. They are found at the top or the middle of secondary forests, depending on variety. Some varieties are more or less adaptable to shade.
Bananas grow well in fairly hot and humid areas that is within an altitude of 0-1800 m above sea level with the exception of "Dwarf Cavendish" which can grow well up to 2100 m.a.s.l. (metres above sea level). For survival a rainfall of at least 1000 mm per year is necessary, but in order to achieve good yields bananas should receive 200-220 mm water per month as a regular supply. For most commercial banana growers this means irrigating during the dry months. Commercially used varieties cannot endure stagnant water conditions, so flood irrigation should only be used if the soil has good drainage.
Temperature is a major factor; the optimum for growth is about 27degC and the maximum 38degC. Plant growth is retarded and chilling injury occurs below 13degC.
Bananas are sensitive to strong winds, which shred the leaves, cause crown distortions and blows plants over, and are susceptible to lodging in the absence of windbreaks. Planting in wind sheltered positions and in blocks rather than strips is recommended. If planted in blocks the plants protect each other against wind.
The best soil for bananas is a deep, friable loam with good drainage and aeration. High fertility is a great advantage and organic matter content should be 3% or more. Bananas, therefore respond well to application of well decomposed good quality composts. The plants tolerate pH of 4.5-7.5 and optimum pH is between 6 and 7.5. Plantains require more fertile soils than table bananas. Agricultural lime or preferably dolomitic lime (Ca + Mg content) can be added to soils that are very acidic in order to make them less acidic and better suited for banana production.
Propagation and planting
Bananas are propagated by vegetative means. There are several types of vegetative planting material. Selection is done according to availability, required amounts and transport possibilities. Smallholders propagate banana mostly by corms / rhizomes (the bottom part of the plant that remains underground and bears several buds which develop into suckers) and suckers. Corms / rhizomes can be used as a whole or in pieces each bearing one or more buds. Using whole corms is laborious, requires a large amount of starting - planting material and involve high transport costs. Using corm pieces is less expensive.
Suckers are produced profusely at the base of each plant. Very young suckers just appearing above the ground, known as peepers, are easy to transport, but will produce first yield after 2 years. Sword suckers, about 75 cm high with corm diameter of about 15 cm, have a well-developed base with narrow sword-shaped leaves. They will produce the first yield about 18 months after planting. Maiden suckers are tall suckers normally 5-8 months, which have not yet set a bunch. They will produce a bunch in the first year. Water suckers, which have broad leaves should not be used for propagation since do not produce healthy banana clumps and the survival rate after planting is low.
Banana plants are also propagated through tissue culture (TC). Normally disease and pest free plantlets are multiplied under controlled conditions. Plantlets are grown in pots and are planted in the field after hardening them off. These tissue culture bananas yield considerably higher than traditionally propagated bananas when planted in clean soil that has not been previously used for banana production in the recent past. They are commercially available in Kenya from both Kenya Agricultural Research Centre, Thika, Jomo Kenyatta University of Agriculture and Technology, Juja and several private companies. The TC banana plants should be minimum 200-300 mm high at planting and have at least 5 healthy dark leaves and wider internodes at time of transplanting.
Planting material should be selected from healthy plants, free of diseases and pests (e.g. bunchy top virus, nematodes and banana weevils), having all the desirable bunch qualities and high yielding ability. It is very important that the planting material is undamaged. Prior to planting, the roots and any damaged part of the rhizome should be removed with a sharp knife. Rhizomes or suckers showing symptoms of disease or pest attack (in particular nematodes or banana weevils) must be discarded.
Planting holes should be at least 0.6 m deep and 0.6 m in diameter and should be filled with topsoil mixed with organic manure. In areas with marginal rainfall larger holes of about 1.5 m in diameter and 1 m are recommended.
The spacing depends on variety, soil conditions and type of planting system. Short varieties, such as the 'Dwarf Cavendish', can be planted in a density of 2500 plants/ha, but more commonly in holes with spacing of 3 m x 3 m. The taller varieties 'Giant Cavendish', 'Robusta' or other strongly developing varieties are set at 600 - 1200 plants/ha or in planting holes spaced at 3 m x 4 m. Experiences in the different regions have led to various recommendations regarding size and depth of hole required, which should be followed. It is recommended to cover the planted rhizome with mulch.
The most suitable planting period is towards the end of the dry season, or at the beginning of the rainy season.
Bananas can be combined with practically any type of cultivated or wild plant, which has similar requirements. Young banana plants are excellent nurses for other crops and forest plants (cocoa, coffee, black pepper etc.), which can be planted very close to the bananas. During the first year bananas should be intercropped with shallow rooted crops for ease of weeding. Following illustrations show 3 examples how to intercrop bananas:
Diversification strategies, Example 1
|These diversifications strategies are suitable for the common eating (table) banana. Because of their high demands on soil, an intensive accompanying vegetation is required. With sufficient foresight and planning, this can later be used to replace the bananas.|
(c) Naturland e.V. (www.naturland.de)
Diversification strategies, Example 2
|If no other crops are to be integrated into the system, then it is sufficient to combine the bananas with forest trees and native fruit trees. If other crops are to be introduced onto an existing monoculture plantation, the fruit carrying pseudo-stems will need to be thinned out.|
(c) Naturland e.V. (www.naturland.de)
Diversification strategies, Example 3
|A wide variety of species and high density of plants should be striven for. The high plant density can be useful for example in suppressing the growth of other vegetation (like grasses, etc.) It also provides sufficient mulching material, which needs to be continually cut and added to the soil. Satisfactory banana production can only be achieved with a large amount of organic material produced on the plantation itself.|
(c) Naturland e.V. (www.naturland.de)
Around 4-6 weeks after the bananas and additional crops have been planted, a primary selective weeding should be done. Frequent shallow weeding is required until the plants shade out weeds. Weeds are controlled by mechanical means (slashing, hoeing, etc.) or by hand. Grasses should be pulled up, and replaced by other non-creeping plants, for instance jack beans (Canavalis ensiformis) and Crotalaria spp.
Surplus shoots need to be regularly cut away from the planted bananas. The number of plants to leave per stool depends on the farmer's preferences. Many plants on a stool will result in a large number of small bunches per stool. Fewer suckers per stool will result in less but bigger bunches than are readily marketable. A common practice is to allow 1 flowering or fruiting stem and 2 to 3 suckers of different size for continuous banana production.
Tissue culture bananas produce large numbers of suckers 1-2 months after planting. These suckers should be cut off at the ground level to allow the development of the mother plant or until the mother plant reaches 1 m in height, at which time 1 following sucker is selected to continue. For good yields it is extremely important to follow the correct sucker selection:
a) Selection should be done when the mother plant is 1 m tall.
b) When the mother plant is 1 m tall 3 vigorous sword suckers facing eastward up to the slope (on sloppy land) should be selected. All other suckers should be cut at base, gorged out in the middle and growing point destroyed. After 1-2 months, the most vigorous sucker should be selected and the rest removed. This will be the first ratoon crop and the first sucker. The first sucker that is produced by the first ratoon sucker should be selected as the second ratoon crop. If the sucker selection is properly done, a large daughter sucker and a small grand daughter, a peeper all aligned in one direction will be seen.
Mulch vegetation (bushes and trees) should be cut back, and the resulting material chopped up and spread around the surface as a mulch. This should be carried out once or twice a year, according to growth.
Regular mulching with organic matter derived from pruning and weeding help to maintain a layer of humus and also enhances microbiological activity in the soil. Pruning and weeding also helps in improving the general hygiene of the plantation, increase light penetration and air circulation, thus stimulating new growth. It also results in a continuous supply of organic matter for mulching.
It is important that the material is spread evenly throughout the entire plantation. However, mulching material should be placed away from the stool (about 60 cm) to ensure that the roots bury themselves deep in the ground at the base of the corm in search of moisture giving good anchorage to the plants. In addition, thrash/mulch may give shelter to banana weevils and should not be left near to the stool.
Addition of Mijingu rock phosphate will promote strong root formation and intercropping with legumes such as mucuna, dolichos or cowpeas for green manure will help supply nitrogen from the atmosphere. These measures will suffice to maintain the fertility of the soil even in situations of continuous banana growing.
The majority of banana varieties cultivated for export purposes require a high soil quality. In natural forest ecosystems, banana plants must be replaced by other species about every 10-15 years. If this is not done the soil will be depleted of nutrients and incidence of pests and diseases may build-up thereby necessitating application of fertilisers and pesticides.
Banana stems are liable to break under the weight of a heavy bunch. As the fruits develop and the weight of the bunch increases, the fruiting stem should be supported with a wooden pole to prevent the whole stem from breaking. Forked poles are used to keep the stems upright and support the weight of the bunch.
Irrigation is necessary in areas with a long dry season but also if rainfall is less than 220 mm per month.
Harvesting banana bunches is usually spread evenly throughout the whole year. Whilst still green, the fruits have a distinctly edged appearance, which gradually becomes almost round as they ripen. The stage of maturity is judged by the angularity of the fingers: The more rounded a finger is in a cross-section, the more mature it is. The fingers are considered mature for harvesting when they are 3/4 round (75% maturity) and still green.
The fruits in a bunch do not ripen at the same pace. If some fruits have begun to turn yellow on the plant, then it is already too late to transport them any great distance, as they quickly become too soft and rot.
Bunches are harvested by cutting them away from the plant just above where the fruit begins. The stem is cut-off with a clean cut at ground level after harvesting the bunch. It is very important that bunches do not fall or bump during transport, as this causes them to blacken and rot. To avoid damaging the bunches during harvesting at least 2 people should be involved in harvesting, in particular heavy bunches or tall varieties, one to do the cutting and the other one to support the bunch so that it does not fall to the ground. An experienced worker, however, can harvest alone.
Harvested bunches should be kept in the shade. It is advisable to handle and transport banana hands rather than the whole bunches because this reduces physical damage. Bunches are dehanded and the hands are deflowered, washed, sorted and packed in carton boxes.
Storage life of matured green bananas ranges from 21 to 30 days at 13-15degC.
Ripening is increased when bunches are packed in closed chambers with restricted air circulation.
Fresh Quality Specifications for the Market in Kenya
|(c) S. Kahumbu, Kenya|