Crop Guide: Growing Banana

Index:

Description
Soil type
Varieties
Climate
Irrigation
Planting density and expected yield
Plant nutrients consumption
Nutrients removal in fruit harvest by different crops
Nutrients contents in various crops (kg/ha)
Relative contents of plant nutrients in banana leaves
Relative contents of plant nutrients in banana fruits
Relationship between soil K content (0 – 20 cm.) and banana yield
The effect of potassium levels, under sand culture conditions, on banana leaf size

1.1 Description

The banana plant is a large perennial herb with leaf sheaths that form trunk-like pseudostems. The plant has 8 - 12 leaves that are up to 270 cm long and 60 cm wide. Root development may be extensive in loose soils, in some cases up to 9 m laterally. Plant height, bunch size and various other charactreristics depend on the variety.

Flower development is initiated from the underground true stem (corm) 9 - 12 months after planting. The inflorescence (flower stalk) grows through the center of the pseudostem. Flowers develop in clusters ("hands") spirally around the main axis. In most cultivars, the female flowers are followed by a few "hands" of neuter flowers that have aborted ovaries and stamens. The neuter flowers are followed at the terminal ends by male flowers enclosed in bracts. The male flowers have functional stamens but aborted ovaries.

Fruits mature in about 60 - 90 days after flowers appearance. Each bunch of fruits consists of variable numbers of "hands" along a central stem. Each "hand" consists of two transverse rows of fruits ("fingers").

The fruit quality is determined by size (finger length and thickness), evenness of ripening, abscence of blemishes and defects, and the arrangement of the clusters. Quality standards may differ in various markets.

Bananas grow well over a wide range of soils. The ideal soil should be well drained but have good water retention capacity. Soil pH should be between 5.5 and 6.5. Soil must not be compact.

1.3 Varieties

Cavendish and Brazilians are the two major groups of dessert bananas. The Cavendish group includes 'Williams', 'Valery', 'Hamakua', 'Grand Nain', and 'Chinese' varieties. The Brazilian bananas are often, incorrectly, referred to as apple bananas. This group includes the 'Dwarf Brazilian'. The Bluefields group, which includes ‘Bluefields’ and 'Dwarf Bluefields', was the leading commercial variety. Currently, this group accounts for less than 1% of banana production in some countries due to its susceptibility to the Panama wilt disease. Starchy cooking bananas, or plantains, are also grown in some countries. Largo, Maia maole, and Popoulu are various plantain groups.

1.4 Climate

Bananas grow best in areas with 2,500 mm or more of well-distributed rainfall per year. Irrigation is needed if rainfall is inadequate or irregular. Banana plants do best in protected areas, because they are susceptible to wind damage. Average temperature of 27^oC (81^oF) and full sun are also beneficial for optimum plant development and yields.

The optimum conditions for ripening bananas are at temperatures of 20-21^oC (68-70^oF) and 90% relative humidity. As the fruit ripens, internal starch gradually turns into sugar.

1.5 Irrigation

Water is probably the most limiting a-biotic factor in banana production. The stringent water requirements of this crop can be evenly satisfied by effective rainfall and by irrigation. The use of these two sources varies widely throughout the world.

Banana is a plant with a rapid growth rate, high consumption of water, shallow and spreading roots distribution, roots with weak penetration strength into the soil, poor ability to draw water from drying soil, low resistance to drought, and rapid physiological response to soil water deficit.

These factors indicate that banana is sensitive to even slight variations in soil water content and that irrigation scheduling is critical. The water holding capacity of the soil, effective rooting depth of the plant, and the depletion percentage of total available water allowed before irrigation, determine the amount of water to apply, while crop coefficient together with the evapo-transpiration data determine the irrigation interval.

In Israel, where water scarcity is crucial, banana orchards are generally grown in net houses in order to reduce water losses by transpiration and reduce leaf tearing by the wind.

1.6 Planting density and expected yield

Banana plants are usually not planted closer than 2 - 3 m apart. Planting density depends on the banana varieties planted and the management practices. The number of suckers developing should be kept to a maximum of 4 or 5 per mat, depending on planting distance and other practices.

Yields of 15, 20 and up to 45 ton/ha can normally be obtained for the 'Brazilian', 'Bluefields' and 'Cavendish' varieties, respectively. Yields of 84 ton/ha have been reported under optimal conditions.

1.7 Plant nutrients consumption

Banana crop is a heavy potassium (K) feeder in comparison to many other crops (Table 1) and it has to be taken into account when a fertilization program is planned.

Table 1: Nutrients removal in fruit harvest by different crops

Fruit crop	Fruit yield (ton/ha)	N	P₂O₅	K₂O
Fruit crop	Fruit yield (ton/ha)	(kg/ha)
Mango	15	100	25	110
Banana	57	322	73	1,180
Citrus	20	22	12	57
Pineapple	84	150	45	530
Papaya	80	225	60	180
Grape	20	160	40	180
Litchi	10	220	35	290

Table 2: Nutrients contents in various crops (kg/ha)

Fruit crop	Yield (ton / ha)	N	P₂O₅	K₂O
Corn	6	120	50	120
Wheat	6	170	75	175
Potatoes	40	175	80	310
Tomatoes	50	140	65	190
Peanuts	2	170	30	110
Sunflowers	3	120	60	240
Apples	25	100	45	180
Avocadoes	15	40	25	80
Citrus	30	270	60	350
Banana	40	320	60	1000

Potassium content in a banana leaf is rather high (Fig. 1), but in fruits it exceeds 50% of its dry weight (Fig. 2).

Figure 1: Relative contents of plant nutrients in banana leaves

Figure 2: Relative contents of plant nutrients in banana fruits

Figure 3: Relationship between soil K content (0 – 20 cm.) and banana yield

(B. L. Smith, South Africa, 1995.)

Potassium level in soil affects not only the yield, but also plant growth (Tab. 3). The higher the K level in soil, the larger foliage area is achievable.

Table 3: The effect of potassium levels, under sand culture conditions, on banana leaf size (Lahav, 1972)

K level (ppm)	Length		Width		Area		Life span		Total foliage area
K level (ppm)	cm	%	cm	%	m²	%	days	%	m²	%
292	129	100	68	100	0.66	100	111	100	75	100
146	123	95	64	94	0.62	94	107	96	67	89
73	104	81	56	82	0.45	68	94	85	44	59
36	101	78	54	79	0.42	64	71	64	32	43
18	106	82	57	84	0.47	71	40	67	30	60
0	86	67	47	69	0.29	44	56	50	18	24
SE (P = 0.01)	5		4		0.06		4		6