Physiological development

Immediately after harvest, the tubers are dormant for a while. The length of this dormant period varies from one variety to another and depends on the growing conditions, the tuber’ smaturity and the presence of tuber injuries. Other important factors are the storage conditions, such as temperature, relative humidity and light. After the natural dormancy, a singlesprout, the apical sprout, will develop.

The sprouting stage is an indication of the tuber’s physiological stage. The apical sproutstage is the transitional stage from dormancy to normal sprouting. In this stage the sprouting of other eyes is suppressed. After a certain length of time, more sprouts will form. They will ultimately branch,while the tuber remains firm. Long, thin hair sprouts and a soft tuber characterise the final physiological stage, senescence. When a
                                        tuber is senile it is no longer suitable for use as seed.