Essentiality of boron in higher plants

Plants need to supply the essential nutrients at the optimal level for normal growth and produce optimal and marketable yields. Over the last centuries, scientists have evaluated the essentiality of different mineral elements for plants from various aspects. They finally introduced 17 elements, including C, O, H, N, P, K, Ca, Mg, S, Fe, Mn, Cu, Zn, B, Mo, Cl, and Ni, as the essential nutrients for plants. Most of the scientists agree on the fact that without the presence of any of these nutrients in the growth media, the plant life cycle is not complete or deviates from the normal process; also, each of these nutrients has a unique function in the plant growth cycle that cannot be done by another nutrient. Boron (B) is one of the essential micronutrients that its necessity for plant growth was first reported in the 20th century. It has vital functions in the plant life cycle, and impairments in numerous metabolic and anatomical processes are induced by its deficiency or toxicity. Suppose the plant life cycle is divided into two general phases, the vegetative phase, and the reproductive phase. In that case, B has unique functions in each of these two phases, and supplying its optimal concentration is needed for the normal completion of each phase. The necessity of B is mainly related to its functions on cell wall strength and development, cell division, fruit and seed development, sugar transport, and hormone development. Investigation of the B essentiality for higher plants is the main focus of the present chapter, and it will be tried to provide further shreds of evidence that plants need B nutrition management for optimal and normal growth and yield.