Role of Magnesium in Citrus Production
Magnesium is needed for many processes in the citrus tree, particularly chlorophyll production.
Magnesium and yield
Magnesium applications have been proven to increase yield, as shown in egyptian trials with navel oranges.
Magnesium and juice content
Increases in yield are largely due to increased fruit weight. However, optimum use of magnesium also boosts juice content of the fruit.
Magnesium effects on TSS and acidity
Soil applied magnesium can increase acidity and decrease the TSS/Acid ratio.
Magnesium effect at growth stages
| Stage | Magnesium effect |
| Fruit Set | Continued strong growth |
| Fruit Enlargement and Maturation | Maintain fruit fill, fruit size and condition |
See more on Citrus Growth Stages.
General guidelines for Magnesium application
Trials show that applying magnesium to citrus crop has provided significant yield increases, largely due to increased fruit weight. Optimum use of Mg also boosts juice content of the fruit. Because this nutrient is needed throughout the main fruiting season, a constant supply is required. Magnesium nitrate is the preferred form offering a synergistic uptake of two beneficial nutrients.
Magnesium deficiencies in Citrus
Magnesium deficient leaves have tip and margin interveinal chlorosis while the base of the leaf blade remains green. These symptoms are more likely to be seen in cultivars that produce higher levels of seed in the fruit, which require a higher Mg nutrition, or where calcitic rather than magnesium-containing dolomitic lime has been used to correct soil pH. Magnesium deficiencies are more likely on weathered, acidic soils which are naturally low in magnesium. Uptake might also be reduced in calcareous soils which have high levels of free calcium.
Where deficiencies are common, magnesium fertilizer applications and/or foliar sprays are effective at correcting problems and should be used as part of the complete nutrient program.
