Climatic requirements
of cotton
 |
- Warm season (tropical) crop.
- Cotton can be profitably grown in regions with rainfall of
850-1100 mm. However, economic yields can not be realized in the
region with a rainfall less than 500 mm.
- 50cm of well-distributed rainfall is necessary for higher yields.
|
- Production depends on vagaries of monsoon since 2/3 cotton area is
rainfed.
- Very sensitive to water logging (both shading).
- Rains during boll bursting period spoil the cotton quality.
- Cotton requires at least 450-500 mm of water for ET inorder to give
higher yields.
- Very sensitive to low temperature during the period of floral bud
initiation during which temperatures of 21 degree C and above are desirable.
- During flowering and fruiting, temperatures of 26-32 degree C are
desirable during the daytime, but the nights should be cool.
- In general, temperatures above 35 degree C are not desirable, however,
when the moisture supply is favourable, the cotton plant is capable
of enduring without permanent injury, very high temperatures (upto 43-45
degree C) for short periods. If these high temperatures persist for
several days, however, the yields will be adversely affected.
- During maturation of bolls and fibres, which is essentially a drying
process, relatively high temperatures are desirable with an average
daily temperature of 22 degree C, 68 days were required for boll maturation
when the average daily temperature approaches 38 degree C, the period
of maturation is still further shortened, but the bolls are smaller
and the fibres do not develop fully, and yields are reduced. For optimal
development and high quality of the fibres, hot and clear days are required.
Under these conditions the quantity of fibres per boll increases, and
the fibre is somewhat shorter but thicker and stronger than otherwise
provided that the moisture supply is adequate.
- When soil temperature fall below 20 degree C, even for short periods,
the uptake of water is slowed down, and the cotton plants may wilt even
when there is ample soil moisture.
- At still lower soil temperatures (below 10 degree C) the geotropism
of the cotton roots is affected, and abnormal root-growth results.
- Excessively high soil temperatures (>40 degree C) also have adverse
effects.
- High light intensities throughout the growing period are essential
for satisfactory vegetative development, for minimal shedding of buds
and bolls and hence for higher yields.
- Reduced light intensities, as a results of cloudiness, reduce the
rate of boll-set and cause excessive vegetative development. The increased
shedding that is frequently observed following rains which occur during
the cotton's growing period, can probably be ascribed to the reduced
light intensity rather than to the effects of the rainfall per
- Reducing light intensity to one-third of normal, reduced carbohydrate
content of the leaves by 24 percent, of the stems by 38 percent, and
of the bolls by 8 percent, the cotton yield being reduced by 47 percent.
- All wild species of Gossypium are short-day plants and do not flower
so long as the day-length exceeds twelve hours.
- Present-day cultivated varieties are generally insensitive to day
length.
- Cannot tolerate frost (180 - 240 frost free days in North is required)
- Crop can be grown up to 1000m altitude
Climate Criteria for Cotton
|
Parameters |
Degree of limitation and suitability class |
| None
|
Slight
|
Moderate |
Severe |
Very
Severe |
|
|
S1 |
S2 |
S3
|
N1
|
N2 |
| I. Climatic Parameters
|
| Total rainfall (mm) |
850-1050 |
|
550-700 |
< 550 |
|
| Rainfall during growing season
|
750 |
|
450 |
< 450 |
|
| Rainfall during boll development
(90-120 days after sowing) |
100-200 |
|
60-80 |
< 60 |
|
| Length of growing period
(days) |
160-180 |
|
120-140 |
< 120 |
|
| Mean tem ºC in growing season
|
22-28 |
|
> 32 |
|
|
| Mean maximum temperature
|
|
|
|
< 36 |
|
| Mean minimum temperature
|
|
|
|
> 19 |
|
| Mean relative humidity in
growing season |
60-80 |
|
|
< 50 |
|
| Length of dry spell (in days)
At seedling stage – At boll development |
< 7 < 14 |
7-10 14-21 |
10-15 21-28 |
> 15 |
|
- S1= most suitable, S2=suitable, S3=marginally suitable, N1=non
suitable could be improved N2=permanently unsuitable.
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Climate and Soils