Growth and fructan contents in plants of Vernonia herbacea (Vell.) Rusby cultivated under nitrogen supply

Abstract

Plants of V. herbacea accumulate high amounts of fructans of the inulin type in the underground organs, named rhizophores. The effect of different concentrations of nitrogen, 6, 12 and 24 kg N.ha-1 supplied as (NH4)2SO4 on plant growth and fructan accumulation was investigated in plants obtained from rhizophore fragments and cultivated in a cerrado area. Young, sixmonthold plants, showed lower amounts of fructans and increases in height, leaf area, dry mass of the aerial organs and rhizophores with increasing concentrations of nitrogen. After 12 months, growth was estimulated only in plants receiving 6 to 12 kg N.ha-1. The data showed that in young plants fructan content is negatively correlated to growth and to increasing nitrogen concentrations. On the contrary, plants with 12 months treated with 24 kg N.ha-1 accumulated 6.0 g fructan per plant while in control plants, not treated with supplementary N, this value was only 3.5 g. These results indicate that the 24 kg N.ha¹ concentration is recomended for fructan production in plants with 12 months.

Asteraceae; cerrado; fructan; inulin; plant growth