ABSTRACT - (Developmental studies in Viguiera robusta Gardn., an Asteraceae from the cerrado). The purpose of this study was to add new information about physiological aspects of herbaceous plants from the cerrado. Plants of Viguiera robusta grown from seeds (achenes) were maintained under controlled photoperiodic conditions, and vegetative growth and flowering were observed during the first life cycle; sprouting was also quantified after senescence and during the subsequent growth period. The achenes germinated better under continuous light at 30ºC and 20/30ºC, and the viability was maintained during 12 months with the seeds kept at 5ºC in glass flasks. The growth parameters used, shoot length, leaf number, dry and fresh mass were not significantly different among the photoperiods tested, the least growth response appearing under 8 h photoperiod. Flowering was first induced in shorter photoperiods but occurred also in the longer ones; flowering plants were also observed when long-short day were given. Plants under 8 h - photoperiod presented a higher number of developed capituli. Young plants show opposite leaves which are alterned to alternate leaves during plant growth. This change in phyllotaxis could not be related to flower induction. When flowering occurs, liberation of lateral buds is observed. These buds form new shoots, specially under short-days. Senescence of the aerial parts is followed by sprouting, which is independent of the photoperiodic treatment applied to the plants but is probably better related to the biochemical/physiological conditions of the reserve underground organ.
Flowering; growth; photoperiodism; cerrado; Viguiera robusta
