Efeito do fotoperíodo no crescimento e no padrão de acúmulo de frutanos em plantas aclimatizadas de Gomphrena macrocephala St.-Hil. (Amaranthaceae)

Abstract

Gomphrena macrocephala is a perennial herb, native to the Brazilian cerrado, with medicinal properties and ornamental potential. As with other plants of the cerrado, it is characterized by well defined phenological phases. This species has been studied because of its particular fructan accumulation in the tuberous root, the variation of these carbohydrates being related with phenological phases. Micropropagated and acclimatized plants were used in the present study to investigate the presence of fructans in tuberous roots and to verify if the photoperiodic conditions interfere on growth, phenological behavior and on fructan accumulation. Short days (8 h) provided lower shoot growth, and induce the appearance of senescence characteristics and accumulation of polysaccharides, as already reported to plants in early dormancy. Long days (12 and 16 h), however, increased shoot growth and resulted in lower fructan contents, similar to what is observed in the vegetative growth phase of this plant.