Physiological and Biochemical Effects of Rare Earth Elements on Plants and Their Agricultural Significance: A Review

The rare earths include the elements scandium [Sc, atomic number (Z) = 21], yttrium (Y, Z = 39), and the lanthanides from lanthanum (La, Z = 57) to lutetium (Lu, Z = 71). Crop responses to application of rare earth elements (REEs) have only been documented in a few countries. The reasons for promoting growth or yield increases are still not sufficiently understood. Recently, physiological interaction of REEs with calcium (Ca), effects on structure and function of cytoplasm membranes, photosynthesis, hormone metabolism, enzyme activity, and water use efficiency have been discussed. This review covers the significance of REEs for agricultural plant production, beginning with a description of the history of their application. The recorded physiological and biochemical effects and responses of selected crops to REEs were also reviewed. Agricultural research needs on REEs are also suggested.