Determination of manganese with crystal violet in plant material in different fertilization
Agricultural University – Plovdiv
12, Mendeleev Str., 4000 Plovdiv, Bulgaria
A study in a multiple-factor stationary field experiment with 16 variants NPK on background with and without annual fertilization with manure was carried out at the Agricultural University in Plovdiv, Bulgaria. The manganese content in the roots of radishes, cultivar Red with white tails, was determined by a new extraction-photometric method with Crystal Violet. The ion-associate of manganese (VII) was completely extracted in a single extraction of only 30 s. The molar absorptivity of the associate was (1.54 ± 0.05) x 104 l mol-1 cm-1. This indicates the high sensitivity of the given reaction. Manganese has been determined by atomic-absorption method, too, in order to compare the results. It was established that fertilization has an effect upon the manganese content in the roots of radishes. The roots of radishes accumulate the highest level of manganese 116.25 mg/kg in a mineral fertilization N:P:K = 3:2:1 with 40 t/ha manure. The relationship between yield and manganese content in radish roots under the influence of fertilization has been established.