Functions of nickel in higher plants: A review

Nickel (Ni) is an essential microelement for higher plants and an important one for many other living organisms. It is present in every part of the biosphere. Higher plants have small requirements towards Ni for their optimal growth and development. That is why its latent and acute deficiencies in nature rarely occur. Soil and water pollution with Ni is a global issue. This is the reason special attention is paid to the effects of higher Ni concentrations on plants metabolism, their organic production, as well as on the possibility of using plants for phytoremediation of Ni contaminated habitats. Depending on the present concentrations, nickel may favourably, unfavourably or not affect the metabolic processes of plants at all (enzyme activity, photosynthesis, respiration, water regime, mineral nutrition, etc.), and thus the growth and development of plants. There are still many questions about the mechanism of Ni influence on the physiological and biochemical processes of plants. Therefore, we believe the presentation of the previous knowledge about the effect of Ni on plants' life processes can contribute to a better understanding of the biotechnical and ecological significance of Ni, and it can indicate further research directions in this field.