Qualidade fisiológica de sementes de soja, milho e tomate expostas a cério e cério combinado com fósforo

Abstract

The rare earth elements are a group of 17 chemical elements, with 15 of them belonging to the group of lanthanides, in addition to scandium and yttrium. Cerium is the most abundant of the REEs, being present in the earth's crust in concentrations as high as those of the micronutrients copper and zinc. For decades, REEs have been a subject of interest, due to their use in various segments of industry and agriculture. In agriculture, the use of REEs has been taking place since 1970 in countries like China, which was the first country to recommend the use of fertilizers containing REEs. In Brazil, the use of REEs is done indirectly through phosphate fertilizers and soil conditioners, such as phosphogypsum. The long-term use of fertilizers is a major source of REEs to the soil. Therefore, the continuous use and application of them can increase significantly the concentrations of REEs in soils. This scenario speaks for the need of studies to verify the physiological responses of soybeans, maize, and tomato seeds when exposed to these elements throughout the germination process, as well as to check which concentrations might have possible positive effects on the physiological quality of these seeds, since these three crops are very demanding in fertilization, mainly with phosphorus. The objective of this study was to evaluate the physiological quality of soybean, corn, and tomato seeds exposed to different concentrations of cerium, either alone or combined with phosphorus. With that, we hope to aggregate additional information that may contribute to unraveling the role of ETRs in plant metabolism, which is still not well known in the world literature. The seeds of these three species were submitted to four concentrations of cerium nitrate and two concentrations of phosphorus. These concentrations were added on the germinating paper in the amount equivalent to 2.5 times the dry mass of the paper and subsequently submitted to the tests for the physiological quality assessments. It can be concluded with this work that the exposure of corn, soybean, and tomato seeds to concentrations of 0.8; 3; 14 and 57 μmol L-1 Ce3+ and Ce combined with 435 and 2608 μmol L-1 P showed no increase in germination and vigor.