With the purpose to evaluate the effect of short (12 hours) and long (13 and 14 hours) photoperiods and air temperature regimes (winter and summer growing seasons) on soybean behaviour, greenhouse experiments were installed at the Federal University of Viçosa, Brasil, from June 1984 to December 1985. In each experiment, under a completely randomized design with 12 treatments (soybean cultivars) and eight replicates: duration of vegetative period from emergency to stage R1 or flowering (DVP, in days); plant height (PH, m); number of nodes per plant at stage R1 (NNP); and duration of soybean cycle from emergency to stage R7 or physiological maturity point (DC, days), were evaluated. The results permit to conclude that: the vegetative period from emergency to flowering and the juvenile period are significantly affected by the photoperiod and temperature differences; shorter photoperiods or higher temperatures anticipate flowering; longer photoperiods under the same temperature regime or higher temperature under the same photoperiod regime result in higher plants.
phenology; plant height; photoperiodism