Tetrazolium: an important test for physiological seed quality evaluation

The production of high quality seeds is linked to a good quality control system. In this system, the tetrazolium test plays an important role in the evaluation of the seed physiological quality, not only due to its relative quickness, but also because of the amount of information that the test presents, such as the indexes of viability and vigor, in addition to providing the diagnosis of possible seed quality problems, such as mechanical damage, insect damage, pre-harvest weathering and deterioration during storage. The development of the test had its beginnings at the end of the 19th century, with great evolution in its concepts and methods in the 20th century. For that, there was the dedication of dozens of professionals in several countries, such as Germany, Japan, Russia, Serbia (former Yugoslavia), United States, Argentina and Brazil. The test indirectly measures the respiration processes that occur in the mitochondria of the cells that make up the tissues of the seeds. The reducing reaction of the solution of the tetrazolium salt under the action of dehydrogenase enzymes results in triphenylformazan, which presents a red carmin coloration. By the interpretation of the resulting staining patterns, seed viability, vigor and the main problems affecting seed quality are determined.