Gomphrena macrocephala St.-Hil. (Amaranthaceae) is a perennial herb from the cerrado with medicinal properties and ornamental interest. Plants can be micropropagated through nodal segments, but acclimatization is difficult. The aim of this study was to establish a relationship between anatomical aspects of the roots and the acclimatization process. When cultures were supplemented with IBA, callus and thick and frangible roots appeared at the base of the microcuttings. A fragile vascular connection between roots and shoots was observed. Abnormal adventitious roots showing alteration in the vascular cylinder and hypertrophy of the cortical cells were also noted. These roots interfere in the transfer to extra vitrum conditions. When no growth regulator was used, no callus was formed, the adventitious roots were similar to those found in seedlings, and acclimatization could proceed. The results show that the origin and the structure of roots formed in the microcuttings play an important role in the acclimatization process and thus in the establishment of the micropropagated plants.
Gomphrena; root anatomy; in vitro rooting; indol butiric acid; vascular connection
