This month we shall learn about two terms used regularly in potato farming; dormancy and dehaulming
- Seed dormancy
Seed Dormancy is a condition where seeds will not sprout even when the environment conditions are favorable for sprouting. There are two types of dormancy innate and enforced. Innate, also called true or absolute dormancy is caused by factors genetically controlled while enforced dormancy is caused by external factors like temperature, light, humidity and age of the tuber.
How to break seed dormancy
The potato tuber undergoes several physiological stages as soon as they are formed on the parent plant. Innate dormancy can be broken naturally by storing tubers in diffused light stores until sprouts are observed or by use of dormancy breaking products like phytochemicals
Sprouted seed potatoes in a diffused light store ready for planting
Dehaulming, in potato production refers to the act of detaching the vegetative part of the potato plant, found above the ground, from the root tubers. When 60-70 per cent of the number of tubers is in seed size grade, dehaulming can be done by use of hand tools or uprooting the entire stems at the ground by pressing around the plant and pulling the stems with the other hand. Alternatively, the foliage is cut at soil level and removed out of the field. At times dehaulming is done earlier in the event of likely build-up of vectors like aphids which transmit virus disease.
After dehaulming the tubers are left in the ground for 2 weeks to harden the skin which reduces injuries during post-harvest handling. When the field is large, spraying with suitable non- selective herbicides is done to kill the foliage and the tubers are left in the soil for 2- 3 weeks for the skin to harden.
Dehaulming of potato done by hand.