Successful potato production depends on adequate water supply throughout the crop’s growing season. Water, which comprises 90-95% of plant tissue and 70-85% of tubers, is probably the most important production factor limiting potato production.
WATER REQUIREMENTS DURING DIFFERENT STAGES OF THE GROWING SEASON
| Growth Stage | Irrigation Requirements | Field Capacity | Shortage | Excess |
| Before planting | 12mm | 60% | – Less stems per plant
– Delayed and uneven emergence |
– Promotes poor stand
– Increased clod formation |
| Planting (Soon after) | 44mm | 80-90% | ||
| Planting to emergence | – No irrigation recommended | 65-80% | ||
| Vegetative stage | 15-20mm | 70-80% | – Restricts plant development and response to fertilization | – Impairs the development of a well-developed root system
– Leaching of nutrients from the root zone |
| Tuber initiation | 25.4mm | 80-90% | – Limits the number of tubers initiated
– Promotes common scab and malformation |
– Can induce tuber disorders (brown center associated with hollow heart). |
| Tuberisation (tuber bulking) | 50.8mm | 80-90% | – Limits foliage development and hastens senescence
– Tuber size is limited and therefore yields are reduced. – Promotes development of common scab. – Alternating deficits result in tuber disorders. |
– Promote luxurious foliage growth that can be conducive to the development of diseases such as early and late blight.
– increases leaching – Leads to enlarged lenticels |
| Maturation | 38mm | 60-65% | – Tubers dehydrate
– Vascular tissue discolors if foliage is killed artificially |
– Enlarged lenticels
– Delay foliage senescence and skin set – Higher reducing sugar content and darker chip color – Promotes weed growth – Decreases relative tuber density |
| Harvest | No irrigation | <60% | – Tubers bruise easily
Clods are conductive to mechanical damage of the tubers |
– Increased incidence of tuber cracks
– Soil sticks tubers, which hampers harvesting and may induce tuber decay during storage. |