Improve the quality of citrus fruits by foliar application of potassium fertilizers.


Foliar fertilization has beneficial effects on the quality, size, appearance, and taste of citrus fruits.


Potassium fertilization is important for citrus fruit; potassium improves the weight, color, thickness of the bark, the caliber or the taste.

Based on studies of Clementine varieties in the Garb region at the National Institute for Agricultural Research using two types of potassium nitrate fertilizer (KNO3) and potassium sulfate fertilizer (K2SO4) ). Results showed that:

The weight

Potassium fertilization improves the weight of citrus fruit which has shown an increase of 6 to 8% on average.

The caliber

The use of three-fold potassium fertilizers also improves the caliber. According to the study carried out, a triple application of foliar fertilizer (nitrate (KNO3)) concentrated to 8%,  gave between 57 and 73% of extra-sized citrus fruit depending on the density of trees on the plot.

The results of the study show that two applications are not enough. This quantity does not make it possible to reach a yield with a high rate of fruits at good caliber.

The color

Potassium gives the fruit bark a more orange color, regardless of planting density.

Thanks to the potassium fertilization, the color can gain up to 10 units of hue compared to an untreated fruit. The Color Index (CI) is the measure that allows evaluating the intensity of the red/orange color, the higher the number, the better.

Warning! Overdose can have the opposite effect. It causes a staining delay regardless of the density.

The thickness of the bark

Potassium fertilization causes an increase in the thickness of the bark. The higher the concentration and the number of applications, the more the bark will thicken. This parameter is interesting for farmers because thick skin induces better resistance to pests and transport.


Potash fertilizers have an impact on the taste of the fruit and more specifically on the acidity and sugar content. An increase in the number of inputs or the concentration results in an increase in the acidity of the fruit.

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