How to reduce potato tuber discolouration

Discolouration or internal blackening or browning of potato tubers is responsible for significant post-harvest losses.

It is caused by the oxidation of phenolic substances, mainly tyrosine to melanin. Potassium, magnesium and boron can all have effects on discolouration and blackening.

Crop Nutrition and Potato Tuber Discolouration

Potassium

Potassium affects enzymatic blackening and after-cooking blackening and low levels of potassium can increase the incidence of after-cooking blackening.

Potassium and potato tuber discolouration

Potassium influences the concentration of organic anions such as citric acid or ascorbic acid (i.e. vitamin C within the tuber). These 2 molecules have an antioxidative function, which decreases the incidence of enzymatic and non-enzymatic discolouration by slowing down the oxidation processes.

This trial from the USA shows the influence of potassium on enzymatic discolouration on two different varieties.

Magnesium

Low magnesium levels can increase susceptibility to enzymatic discolouration.

Magnesium and potato tuber discolouration

This trial from the USA shows the influence of magnesium on enzymatic discolouration.

Boron

Boron reduces the oxidation of phenols that are responsible for enzymatic discolouration. Thus, a good supply of boron reduces the occurrence of enzymatic discolouration in potato tubers.

Boron and potato tuber discolouration

Other crop management practices influencing potato tuber discolouration

  • Selecting the right variety to meet production needs
  • Taking care during harvest and grading to reduce physical damage and bruising
  • Holding capabilities are present
  • Irrigating to prevent, or minimise diseases such as common scab
  • Harvesting in good conditions to avoid physical damage and disease infestation.
  • Controlling temperatures and humidity in storage

Recommended Yara fertilisers for potatoes

YaraVita ZINTRAC 700
YaraVita Zintrac 700 is a highly concentrated flowable zinc
YaraVita MAGFLO 300
YaraVita Hydromag Liquid is a highly concentrated flowable formulation contains almost 3 times more magnesium than epsom salts.
YaraVita BORTRAC 150
YaraVita Bortrac 150 is a concentrated liquid boron formulation manufactured to exacting quality control standards to guarantee consistent analysis, crop safety and product performance.
YaraMila 8-11-20
YaraMila (8-11-20) is a high quality, granular NPK product which also contains sulphur and micronutrients.
YaraMila COMPLEX
YaraMila Complex (12-5-15) is a high quality, prilled NPK product which also contains magnesium and sulphur as well as micronutrients.
YaraBela CAN-27
YaraBela CAN-27 contains 27% total Nitrogen, 50% in the nitrate form
YaraLiva NITRABOR
YaraLiva Nitrabor (15.5% N + 18% Ca + 0.3% B) is a high quality calcium nitrate product, with added boron, for field application.
See all fertilisers products

See all potato nutrition articles