A new protocol for estimating the determinacy – how crops utilise fertilisers – of potato varieties will be released in the next few months and will be added to the AHDB’s Nutrient Management Guide (RB209).
This should help breeders and those involved in variety development, save time and money when producing nitrogen recommendations for new varieties. From this, growers and agronomists will gain more accurate nitrogen/determinacy groupings for both new and existing cultivars, and thus fine-tune the N rates applied to crops.
A key component of nitrogen fertiliser recommendations, as used in the AHDB Nutrient Management Guide, is the nitrogen (determinacy) group. These are based on four groups: Group 1 (very determinate) through to Group 4 (very indeterminate).
Potato varieties such as Accord, Estima and Innovator are part of Group 1 as they cease leaf production after the first (or indeed second or third flowers) but when compared with indeterminate varieties, they will produce fewer leaves.
In contrast, varieties classified as group 4 determinacy, for example Cara, Markies and Royal, continue to produce leaves and flowers until they are curtailed by shorter days and frost. It is essential to know the grouping of your variety, in order to calculate the correct nitrogen recommendations, according to Alice Sin, an AHDB resource management scientist.