What is the role of potassium in apple production?

Positive effect of potassium

When soil reserves are low, yield responses have been recorded following potassium applications of up to 600-700 g / K / tree in low density orchards.

Negative effect of potassium on yield

Potassium applications must take into account its level in the soil; when it is high, too much fertiliser can lead to lower yields.

Potassium and Sun Scorch

A high potassium concentration in fruits reduces the frequency of solar scalds. But a high concentration of potassium promotes the appearance of bitter pit. A correct balance K / Ca is therefore important to preserve the quality of the fruits.

Potassium and colouring of the fruits

By playing an important role on the increase of the rate of anthocyanin, the potassium improves the colouration of the fruit. This effect has been demonstrated on several varieties.

Potassium and Bitter Pit

The commonly accepted optimum value of the K / Ca ratio is around 15 for 40-60 g fruits and should not exceed 30 at harvest to minimize the risk of biting pit. This index can be measured on young fruits and used to prescribe the additional sprays needed to correct any imbalances.

Potassium and soluble sugar content

Potassium, through its action in the transport of sugars, plays an important role in increasing the content of SST (or ° Brix).