Climate

• Potato basically requires relatively mild temperature during early growth and cool weather during tuber development.
• It does well under well-distributed rains or moist weather situations to high temperature, humidity rains are not conducive to potatoes as these lead to insect-pest, disease, viruses epidemics.
• Impeded drainage or lack of aeration also is considered harmful as it restricts the tuber development.
• Therefore, climatic conditions are very crucial for determining the potato yield.
• Its general and specific climatic requirements are delineated as under.

General climatic requirements

• Potato is a temperate or cool season crop which needs a low temperature, lower humidity, less windy and bright sunny days.
• It thrives best in cool regions where there is sufficient moisture and fertile soil.
• Potato needs about 25°C at the time of germination, about 20°C for vegetative growth but between 17-20°C for tuberization and tuber development.
• It is noticed that higher temperature has an adverse effect on the tuber growth, where as temperature above 30°C stops tuber formation completely.
• It is probably because at higher temperature the rate of respiration increases and the carbohydrate formed by the process of photosynthesis is consumed rather than stored in the tubers.
• Under higher temperature the plants are elongated leaves become wrinkled and plants have silky appearance.
• Tubers do not develop under such situations.
• Cloud days, rains and high humidity are very congenial for spread of fungal, viral and bacterial diseases, and such conditions are not good for the crop.

Specific Climatic Requirements of Potato

• Potato is a crop of temperate climates and its importance is great both for human consumption and for industrial uses.
• There are different varieties of potatoes which are classified on the basis of the length of the vegetative period.
• There are early varieties with 90 days vegetative period; others are medium verities with 90-120 days of vegetative period and still others are late varieties with over 120 days of vegetative periods.

Temperature

• Potatoes are planted when the soil temperature at a depth of 4 inches is 8 ° to 10 °C. When they are planted at a higher temperature, the tubers are damaged, but when they are planted at a lower temperature, the sprouting is retarded.
• It has been estimated that a mean daily air temperature of 10 ° C, the length of the period from sowing to sprouting is 27 days.
• But when the mean daily air temperature is 22 ° C, sprout appears after 12 days.
• Experiments have shown that a most favourable temperature for the potato tubes is 18 ° to 20 ° C. At 22 ° to 25 ° C the formation of the tuber is retarded and beyond 29 ° C it completely stops.
• Mild frost to the extent of -1° C partially damages the potato leaves, but when the temperature falls below -2° C, the exposed parts of the most of the varieties are destroyed.

Moisture

• The water requirements of the potato crop during its vegetative period are not very high.
• It has been estimated that rainfall of 15 to 20 cms or an equivalent amount of irrigation is sufficient for the normal crop.
• At the time of germination, the crop requires little external moisture, because the potato tubers themselves contain adequate amount of water. However, as the leaves grow after sprouting, the water requirements of the crop increase.
• The optimum soil moisture for the potato crop is 65 to 80 percent at the field capacity.
• Just after sowing and before sprouting, heavy rains adversely affect the crop.
• Alternate dry and rainy weather leads to an excessive growth of potato plant and encourages the formation of the off-shoots in the young tubers.
• Potato requires a high light intensity if the crop remains in shade or if it is too densely planted, the yield is adversely affected.