Understanding dormancy rankings of potato

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 its duration, though also influenced by other factors, is a varietal characteristic. Across varieties, there is a wide range of different dormancies and knowledge of a variety’s expected dormancy period can provide options for storage, for example to appropriately time sprout interventions for long term storage or likely sale periods. However the availability of independent data on dormancy scores for commonly grown varieties is both sparse and conflicting. The conflicts are very likely to be due to variations between the different assessment methods. The establishment of a standardised assessment methodology, and its use to rank the dormancy of many current varieties was needed.

AHDB commissioned this project to generate relative dormancy data from a range of varieties representative of the different end markets for potatoes.

Varieties were stored and assessed at Sutton Bridge Crop Storage Research. The 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.

Results

Seasonal differences in dormancy duration were observed over the three years of the trial. Generally longer durations were found during trial year 2 (2019-20). Approximately 40% of varieties were within a 10% difference of dormancy duration between trial years 1 and 2, 25% between years 2 and 3, and 67% between years 1 and 3. Despite this variation relative dormancy was approximately maintained throughout the trial years to date. However, some varieties, including Arsenal, Melody and Royal, had very different dormancy durations between years of the trials and substantially changed relative position in different years of the trial.

A literature review summarising published information on dormancy and quality changes during storage was also produced (2021).

Aims and Approach

Aim: To provide a reliable ranking of the dormancy characteristics of important varieties grown in the UK.