Nigeria accounts for 60% of the world's yam output and 74% of the total production in West Africa. Grown as a staple food, the tuber of the yam plant is economically quite important. The yam tuber is essentially a starchy or carbohydrate food and its principal nutritional function is the supply of calories.
The challenge, however, is that the onset of maturity in yam is not well understood and the date of harvest often bears no relationship to the functions and activities of the tuber. As a result farmers aren't able to accurately determine the best time to harvest the crop.
The accumulation of starch in the tuber reached its peak when accumulation of starch in the leaves made them turn yellow. The starch content of leaves was the determining factor for when the tuber had reached maturity. The yam tuber is fully matured when minimum starch content was obtained in the leaves. These low levels of starch content were marked by the yellowing of the lower leaves of the plant. This provided a clear indication of the earliest possible time to harvest the yam.
By using the simple technique of harvesting when the lower leaves begin to turn to yellow, farmers can harvest before the entire leaves decompose and be sure of matured yams being harvested. It will also mean that farmers will be able to use the fields to plant for income-earning crops such as vegetables before the end of the farming season. This could translate into improved livelihoods for farmers.
Source: phys.org
