Agriculture Reference
In-Depth Information
drainage can arise. Sandy-clay loam soils are best suited for banana cultivation with
the optimum soil texture being around of 30:10:60 (clay:silt:sand) (Robinson and
Galán Saúco
2010
).
It is possible to cultivate bananas in soils of 40-60 cm in depth (vitro plants
cultivated to a few -one or two- cycles, (Israeli and Nameri
1987
), but the recom-
mended soil depth for banana cultivation should be a minimum of 80 cm or, even
better, 1.20 m.
Soto (
1995
) recommends that bananas are best cultivated within a soil pH range
of 4.2-8.1. For optimum production, the soil pH, measured in water, should be
between 5.8 and 6.5 (5.0 and 5.8 if measured in potassium chloride). The most im-
portant cations are potassium (K), calcium (Ca), magnesium (Mg) and phosphorus
(P). In certain soils there may be a specific shortage of minor elements such as zinc
(Zn) or boron (B). The banana crop is very demanding on K and large quantities of
this element are removed from the soil. Potassium has been the most widely studied
element in banana soils, and this crop is very sensitive to cation imbalances (Lahav
1995
). In particular, the K/Mg and Ca + Mg/K ratios are very important. Potassium
deficiency symptoms may be observed when soil Mg or Ca reserves are high, rela-
tive to K (Robinson and Galán Saúco
2010
). Salinity is usually only a problem in
dry mediterranean climates, such as Israel and the Canary Islands, often occurring
in the absence of summer rain or poor quality irrigation water. The optimum ratio
for soil K/Na is 2.5 with Na ideally less than 2 % of the total exchangeable cations
on a mili-equivalent % basis. Values of electrical conductivity in the soil solution
higher than 2.5 dS/m have been found detrimental for root development (Rodríguez
and Lobo
2008
).
Climatic Requirements
Although the major banana growing areas of the world are geographically situated
between the equator and latitudes 20 °N and 20 °S there are commercially profitable
plantings in the subtropics at latitudes close or even slightly higher than 30 °N and
30 °S. Climatic conditions in the tropics are characterised by comparatively small
day to night and summer to winter temperature fluctuations. In contrast, the main
climatic characteristics occurring in the banana growing areas of the subtropics are:
(a) wide day to night and summer to winter temperature fluctuations, (b) high and
low temperature extremes in summer and winter respectively, and (c) poorly dis-
tributed, low annual rainfall.
Temperature is the main limiting factor of banana growth where enough water is
available. Robinson and Galán Saúco (
2010
) indicate the cessation of new leaf emer-
gence when the mean daily temperature threshold [(maximum + minimum) ÷ 2] falls
below 16 °C. The net rate of growth (dry matter assimilation) ceases at temperatures
below 14 °C, with 22 °C considered as the optimum temperature for both growth
and flower initiation, and, approximately 31 °C as optimum for leaf emergence rate.
In general, around 27 °C is considered as the best overall mean temperature for
