B is responsible for cell wall formation, stabilization, lignification and xylem ifferentiation. It is involved in nucleic acid metabolism. It facilitates the transport of K in guard cells as well as stomatal opening. Two types of deficiencies are caused due to  B shortage viz., (i) natural deficiency because of the lack of B in the soil forming minerals and (ii) induced deficiency by over liming.

Krochmal and Samuels (1968) reported that deficiency of B causes dwarfing of young plants and slight chlorosis of the younger leaves. Initial symptoms are seen on the roots, which show suppressed lateral root development and sometimes death of the root tip. This is followed by the emergence of short lateral roots with swollen ends. B deficient plants tend to be short due to  reduction in internode length and mildly affected leaves develop  chlorosis consisting of numerous minute light grey or brown spots concentrated mainly at the tips and margins of leaf lobes. Severely affected leaves are reduced in size, deformed and with short petioles. A distinctive symptom of B deficiency is the development of lesions from which a brown gummy substance exudes out on upper petioles and stems. The stem lesions may later coalesce and develop into cankers.