Boron (B) regulates transport of sugars through membranes, and also plays a key role in cell division, cell development and auxin metabolism.
Under condition of boron deficiency growing buds die, and plants appear bushy, having shorter internodes. Leaves thicken and roll upward; leaf tissue darkens and collapses. Brown necrotic patches appear on tubers, and internal rust spot are formed. (Fig. 25)