Boron (B)

Role in plants

Boron is essential for cell wall structure, membrane function, sugar transport, and pollen tube growth (fruit set). It is poorly mobile in many crops.

Deficiency symptoms

• Brittle, distorted young leaves
• Cracked stems/petioles
• Poor pollination and fruit set
• Hollow or corky tissues in some crops
• Death of growing points in severe cases

Toxicity symptoms

• Leaf tip and margin burn
• Yellowing progressing to necrosis
• Often appears first on older leaves

Natural sources

• Parent material and soil solution
• Some irrigation waters (variable)

Fertiliser sources

• Boric acid
• Sodium borate / Solubor-type products

Plant uptake forms

• H3BO3 (boric acid)
• Borate species depending on pH