High temperature tolerance in cotton 2013-14
Cotton originates from hot climates, but does not necessarily yield best at excessively high temperatures. The optimum temperature range for cotton is 20 – 30°C (Reddy et al., 1996.
However, the average maximum daily temperature in the US Cotton Belt is always above 32°C, i.e. well above the optimum for photosynthesis and reproductive development. In
South Africa daytime temperatures during flowering (the most sensitive stage) also often exceed 30°C. This is considered a major reason for lowered and variable yields
experienced in cotton production. Cotton yields in Arkansas are less than half of the theoretical maximum (Baker, 1965).