*3.2.2 External factors*

In general, environmental factors would have a very limited impact on dormancy. However, the effects of nitrogen, temperature and light were reported in the experiments. Nitrogen fertilization and relatively high temperatures would shorten the dormancy time. Whereas the light effect would have no significant impact.

The agricultural calendar for potato seed production should take into account the calendar for potato consumption production, the dormancy of tuber seed and the fact that tuber seed is generally earlier harvested when the tuber is still small. Therefore, three examples of calendars are given considering the dormancy duration of Potato varieties in CA countries (**Figures 3–5**), and where very early varieties, early and late ones cannot be scheduled in the same ways.
