Search

Rare earth elements (REEs) are a group of chemical elements that include lanthanides as well as scandium and yttrium. Today REEs are used in various industries, such as agriculture where they are used as micro fertilizers and feed additives, the latter being used in medicine as well. There is no indication that REEs might be essential for any form of life. At lower concentrations, they can favorably influence certain physiological processes of plants (enzyme activity, hormone content, photosynthesis, seed germination, plant growth, etc.). They may induce an increase in some antioxidant systems and thereby increase the tolerance of plants to environmental stressors caused by high concentrations of heavy metals, herbicides, lack of water and essential nutrients, UV radiation and oxidative stress. Thus, their favorable effect was documented regarding the yield of cultivated species as well as the effect of their chemical composition on the content of vitamin C, soluble sugars and essential elements, reduction of the concentration of toxic heavy metals, improvement of the quality of wheat kernel for different uses. REEs have been commonly used as feed additives in organic and inorganic forms in livestock production. The available literature on the use of REEs as feed additives in livestock suggests positive outcomes (affected various physiological processes, increase in milk, egg and meat production, promoted growth and reproductive performance), but further investigation and results are needed before extending their use to zootechnical purposes.

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.