There are three main criteria which define the quality of potato: tuber quality, skin finish and storage and cooking quality. A balanced crop nutrition program is important to help manage all of these criteria.
Tuber quality, whether it is dry matter content, starch content, internal disorders or cooking ability is critical for the end user.
Nitrogen encourages leaf and tuber growth and maximizes starch production, phosphate maintains leaf and tuber growth and influences starch quality and content, potassium maximizes water uptake and dry matter production and can help reduce the level of bruising, calcium minimizes internal rust spot and black spot, magnesium ensures a strong photosynthetic capacity and good growth, boron helps reduce internal rust spot and enzymatic blackening.
Skin finish is becoming more important as consumers increasingly demand potatoes with clean, attractive skins, particularly when buying pre-packed or loose potatoes. Tubers with surface diseases are not only less attractive, they are likely to have a reduced storage life.
Correct balanced nutrition of the plants will reduce the incidence of tuber skin disorders and improve the skin finish. Calcium strengthens tuber skins providing better resistance to diseases, boron enhances the effect of calcium by improving uptake and so and can reduce levels of common scab and other tuber diseases, zinc can minimize powdery scab and sulphur may reduce both powdery and common scab infection.
Storage and Cooking Quality
Storage and cooking quality cannot be overlooked and once the crop has been harvested the job is not finished as in most countries potatoes have to be stored to provide continuity of supply throughout the year. Tubers which are less prone to bruising or discolouration will store significantly better and retain better cooking qualities.
Correct balanced nutrition of the crop prior to harvest will influence the storage and cooking quality of the potato tubers. Potassium, calcium, magnesium and boron all have positive effect on potato tuber storage and cooking quality by reducing tuber bruising, enzymatic blackening and discolouration.