Boron's Role in plants

Boron plays an important role in regulating plants’ hormone levels and promoting proper growth. Boron increases flower production and retention, pollen tube elongation and germination, and seed and fruit development. Deficiencies that might not seem to affect vegetative growth might show up in poor fruit, nut, and seed production, bud and flower drop, and poor quality crops. For example, boron deficiency can cause incomplete pollination of corn or prevent maximum pod set in soybeans.

Boron is essential for normal development of root nodules in legumes such as alfalfa, soybeans, and peanuts.

Boron and calcium are involved in cell wall structure, and boron facilitates the movement of calcium into and within plants. For example, a peanut ailment called hollow-heart can occur when a boron shortage limits calcium movement, normal cell wall development, and cell division. 

Root tips, new leaves and buds, and other active parts of the plant rely heavily on adequate boron. Boron also ensures the healthy transport of water, nutrients, and organic compounds to these growing portions. A shortage of boron will show up first in these areas. For example, rosetting or stunting of plants is a common symptom of boron deficiency in alfalfa, clovers, and legumes.