The root system is the main organ for water and mineral nutrient absorption in plants, as well as the
organ for synthesis, assimilation and transformation of important substances such as amino acids and
hormones in the plant body. Therefore, the growth and activity of roots directly affect the growth, nutrient
level and yield level of individual plants, and it is of practical importance to determine the root vitality.
Plant roots can oxidize α-naphthylamine adsorbed on the root surface to produce red α-hydroxy-1-
naphthylamine, which is precipitated on the surface of oxidized roots, causing this part to be dyed red. α-
Naphthylamine interacts with sodium p-aminobenzene sulfonate and nitrite under acidic conditions to
produce a red azo dye. Root vitality can be expressed by the reduction of α-naphthylamine.
Reagents and Equipment Required but Not Provided:
Spectrophotometer/Microplate reader, water bath/incubator, adjustable pipette, filter paper, micro
glass cuvette/96 well plate, distilled water..
