Role of Manganese in Citrus Production
In citrus production, manganese is involved with photosynthesis, efficient use of N, protein metabolism and enzyme activation.
Manganese and yield
Both soil application and foliar sprays of manganese increase yields in deficient trees. This is mainly as a result of increasing the number of fruit per tree.
Manganese and fruit number
Yield increases as a result of manganese nutrition are mainly due to a higher number of fruit per tree, as can be seen on Balady oranges in Egypt.
Mn and Zn combined and yield
Manganese deficiency is often associated with zinc and iron deficiencies. These are common on calcareous soils. In practice, a combined foliar application of Zn and Mn is often more effective in alleviating the respective deficiency symptoms, than single sprays on their own.
Mn/Zn sprays - effects on quality
Manganese, often in association with zinc, increases TSS contents of the fruit. The image above shows quality improvement on mandarins in India.
Manganese and vitamin C content
Manganese can also improve the ascorbic acid content of the fruit. As a result, manganese has little influence on the TSS/Acid ratio and this combination of improved sugars and acidity content produces more desirable fruit for the consumer.
Manganese effect at growth stages
| Stage | Manganese effect |
| Fruit Set | To maintain fruit yield and quality should be applied with each leaf flush |
| Fruit Enlargement and Maturation | Maintain fruit yield |
| Post Harvest | When needed for post harvest foliage flush |
See more on Citrus Growth Stages.
General guidelines for Manganese application
Persistent, severe manganese deficiency reduces cropping, growth and yield. Manganese is involved with photosynthesis, efficient use of N, protein metabolism and enzyme activation. Both soil application and foliar sprays increase yields in deficient trees. This is mainly as a result of increasing the number of fruit per tree.
Manganese deficiencies in Citrus
Manganese deficiency is usually seen on young leaves as a mottled yellowing of the leaf. The veins stay green whilst the interveinal areas are light green to yellow. In extreme cases white spots can also be found between veins. The usual practice is to apply Mn foliar sprays with zinc to overcome any deficiency. Mn and Fe have strong interactions; plants deficient in Mn will be high in Fe and vice versa.
