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close this bookTraditional Storage of Yams and Cassave and its Improvement (GTZ)
View the document(introduction...)
View the documentPreface
View the document1 Introduction
View the document2 Socio-cultural aspects involved in the production of roots and tubers
View the document3 Basic comments on the storage properties of roots and tubers
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
close this folder4.5 Causes of storage losses for yams
View the document(introduction...)
View the document4.5.1 Dormancy
View the document4.5.2 Transpiration
View the document4.5.3 Respiration
View the document4.5.4 Germination
View the document4.5.5 Rot due to mould and bacteriosis
View the document4.5.6 Nematodes
View the document4.5.7 Insects
View the document4.5.8 Mammals
close this folder4.6 Traditional storage systems for fresh yams
View the document(introduction...)
View the document4.6.1 Leaving the yam tubers in the ridges after maturity
View the document4.6.2 Storing the yam tubers in trench silos
View the document4.6.3 Storage of yam tubers in heaps on the ground
View the document4.6.4 Storage of yam tubers in clamp silos
View the document4.6.5 Storage of yam tubers under a conical protective roof made of maize or millet stalks
View the document4.6.6 storage of yam tubers in mud huts
View the document4.6.7 The storage of yam tubers in the yam barn.
close this folder4.7 Measures to improve traditional yam storage
View the document(introduction...)
View the document4.7.1 Care in harvesting transport and storage
View the document4.7.2 Curing
View the document4.7.3 Influencing dormancy
View the document4.7.4 Influencing the storage climate
View the document4.7.5 control of rot
View the document4.7.6 Control of nematodes
View the document4.7.7 Control of insects damaging stored produce
View the document4.7.8 Measures for protection from mammals
View the document4.7.9 The improved traditional yam barn
close this folder5 Cassava
View the document(introduction...)
View the document5.1 The environmental requirements of cassava
View the document5.2 The cassava root
View the document5.3 Economic aspects of cassava production
View the document5.4 Causes of limitations to storage for fresh cassava roots
close this folder5.5 Ways of and limits to. storing fresh cassava roots
View the document(introduction...)
View the document5.5.1 Storing cassava roots in the soil after maturity
View the document5.5.2 Traditional methods of storing fresh cassava roots
View the document5.5.3 Storage of fresh cassava roots in clamp silos
View the document5.5.4 Storing fresh cassava roots in crates
View the document5.5.5 Storing fresh cassava roots in a dip
View the document5.5.6 Storing fresh cassava roots in plastic bags
View the document5.5.7 Use of modern methods to store fresh cassava roots
View the document5.5.8 Measures to prepare fresh cassava roots for storage
View the document5.5.9 Suitability of storage systems for fresh cassava roots on a small farmholder level
close this folder5.6 The processing of cassava roots
View the document5.6.1 The purpose of processing
View the document5.6.2 Hydrogen cyanide and its release
View the document5.6.3 The production of cassava chips
View the document6 Summary
View the document7 Bibliography

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).