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close this bookTraditional Storage of Yams and Cassave and its Improvement (GTZ)
close this folder4 Yams
View the document(introduction...)
View the document4.1 The environmental requirements of yams
View the document4.2 The yam tuber
View the document4.3 Farm-economic aspects of yam production
View the document4.4 Yam harvesting
Open this folder and view contents4.5 Causes of storage losses for yams
Open this folder and view contents4.6 Traditional storage systems for fresh yams
Open this folder and view contents4.7 Measures to improve traditional yam storage
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4.4 Yam harvesting

There are two processes of harvesting yams:
- single harvest
- double harvest

The single harvest involves harvesting all the tubers of a plant in one working procedure. The time for harvesting is not a critical date since one month prior to wilting point (sign of physiological maturity of the tuber) the growth of the tuber is extensively completed. Harvesting should however be finished within 1 - 2 months of the wilting point, or otherwise losses due to tuber rot must be expected (ONWUEME, 1 978).

The double harvest is divided into a first and a second harvest Depending on the sort of yam, the first harvest takes place about 4 - 5 months after emergence of the plants. The tubers are carefully uncovered and separated from the plant without damaging it. After the harvest, the bed which has been dug open is re-prepared The plants react to this interference with increased production of tuber tissue so that a second harvest can take place after the wilting point.

The double harvest the properties of the tuber The tubers from the second harvest have pronounced "planting features.' and are less suitable for eating. Thus the high work input in the process of double harvesting is mainly for the purpose of producing plants for vegetative propagation.

The tubers from the first harvest are available early. They are highly estimated and attain correspondingly high prices on the markets.

The double harvest is a process with a very high input of labour. Mechanisation is very difficult which means work relief through the use of technical progress is hardly possible (ONWUEME, 1978).