The effect of nitrogen surplus in fertilizing rates applied to Echinacea purpurea (L.) Moench. On the production of its active substances

Pot experiments were conducted to study the effect of nitrogen surplus in form of NH: and NO; in relation to the presence of ions Ca2+, Li+, Na+ from applied fertilizers, and the effect of SO42-, HCO3- and Cl- on the production of active substances in Echinacea purpurea (L.) Moench. The effect of carbon on nitrogen nutrition of plants was studied in variants with additions of cattle dung, cattle manure, mustard, white clover, wheat straw with constant C contents, and parallelly with constant N content at different C : N ratios. Variations in nitrogen content in plants (N-min + N-tot) were examined in relation to variations inactive substances in plants. Variations in total, mineral and mineralizable nitrogen in the soil of vegetation pots were also studied. No significant difference was demonstrated between the forms of nitrogen applied by N-fertilizing and its effect on the content of active, substances in E. purpurea; the study of cation effects showed that contrary to calcium effects the production of active substances was supported by univalent cations moderately but statistically significantly. Different effects of anions SO42-, Cl- and HCO3- are statistically insignificant at fertilizing with ammonium nitrogen. Even though the C : N ratio is satisfactory, the production of active substances is reduced by applications of organic manures apparently through an increase in mineralizable nitrogen and a decrease in mineral nitrogen in the soil of vegetation pots. It is surprising that both fast and slow decomposable carbon sources, i.e. glucose and wheat straw, are ineffective in this aspect. Similarly like in the preceding variants, the largest immobilization effects in variants with constant N contents in organic matter additions were observed in mustard, not in straw as expected. Variations in the content of nitrogen forms in pot soil are surprisingly in good agreement with the production of active substances in E. purpurea plants. Variations in the contents N-min + N-tot in plants in relation to variations, in their contents of active substances have not only a nonlinear course but they are evidently a result of at least two different processes. A relation of the production of active substances in E. purpurea to increasing nitrogen rates expressed by an N-min: K ratio was also studied. Maximum production was attained at a 6 : 1 ratio in the soil used.