Natural dormancy: independent data now available

A number of factors contribute to effective sprout suppression and, where possible, strategies should make the best use of all of them. One such factor is dormancy.

Potato tubers have a dormancy period during which they show no sprout growth and it’s duration, though also influenced by other factors, is a varietal characteristic. Across varieties, there is a wide range of different dormancies and those with longer dormancies can help reduce the reliance on sprout suppressants.

However, the current data on varietal dormancy is of variable quality and AHDB has commissioned a trial to generate relative dormancy data from a range of varieties representative of the different end markets for potatoes.

For the first two years of the trial, varieties were grown on Strategic Potato (SPot) Farms, stored, and assessed at Sutton Bridge Crop Storage Research. These common conditions for growing and storing the potatoes provided the basis for relative dormancy ranking. For the trial the working definition of dormancy break was when more than 50% of the tubers stored at 15 °C had sprouts of 3mm or greater.

In the second year of the trial, seed from the same stock of each variety was grown at both SPot North and West to investigate the effect of different growing conditions (site) on dormancy. Figure 1 shows the average dormancy (at °15 C) for varieties across both trial sites. This relative dormancy ranking shows the wide variation found in varieties used within Great Britain. Dormancies range from 160 to 260 days from Tuber Initiation (40 -140 days from harvest).

Figure 1. Average dormancy (at °15 C) for varieties grown at SPot West and SPot North. * variety planted only at SPot West.

There are many factors to consider for potato variety selection including yield, market demand, disease resistance etc. The removal of CIPC has focused attention on the importance, and costs, of sprout suppression. Dormancy is an available tool and can be given consideration in variety selection using, for example, the figure above to compare potential varieties.

You can hear Glyn discuss these results in more detail our storage webinar below.

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