Boron

Boron is an important trace element because it is involved in plant development, cell division, cell wall structure and pollination. Boron deficiencies can lead to stunting and deformation of growing points, as well as inhibited leaf expansion, a property that directly impacts the plants ability to photosynthesise. Boron is responsible for straight trees, and is therefore used in forests, for trees used for wood and for palm trees. The window between deficiency and toxicity is very narrow and because boron is immobile in plants, it is common for young plants to show deficiency symptoms. A boron concentration higher than 5 ppm in agronomic crops (stable food crops such as rice and wheat) can be toxic. Bisley sells multiple boron-based fertilisers, where the most commonly used is boric acid. 

Hooda, P. (2010). Trace elements in soils. Wiley.