Role of Boron in Citrus Production

Boron is involved in various enzyme systems and in carbohydrate metabolism and translocation.

Boron, like calcium also has an important role in cell structure and cell wall integrity.

Boron and yield

Citrus is highly sensitive to boron producing significant yield responses in trial.

Boron and yield in lime, India

Yield increases result from a higher fruit number per tree, minimizing fruit drop and from boosting fruit weight.

Boron and juice content

Adequate supplies of boron have a positive effect on juice content. They will also bring forward ripening and maturity, often improving crop marketability.

Boron and TSS

Boron influences fruit quality by increasing sugars in the fruit.

Boron and vitamin C

Boron can also improve vitamin C content in the fruit.

Boron effect at growth stages

Stage	Boron effect
Fruit Set	Minimize fruit drop, prevent fruit deformities or storage problems from peel breakdown
Fruit Enlargement and Maturation	Maintain fruit yield

See more on Citrus Growth Stages.

General guidelines for Boron application

Boron supply needs to be properly managed, as there are only small differences between being deficient and being toxic. Soils with high boron levels – such as old marine soils – need good water management to reduce the risk of boron toxicity. In these situations it is important to use rootstocks that are tolerant to boron.

Boron deficiencies in Citrus

Boron deficiency can occur when growers use fertilizers without added micronutrients, after a long period of drought or in soils naturally low in boron (e.g. sands). The tree loses its apical dominance and sends out multiple shoots.
Symptoms also include corkiness of leaf veins and gum spots in the albedo of the fruit and flesh near the rind. Seeds may be shrivelled and the fruit may develop a gray-brown discoloration.