EVALUATION OF PHENOLOGICAL STAGES OF FORAGE SORGHUM CULTIVARS IN DIFFERENT SOWING TIMES

Abstract

To obtain information about the behavior of forage sorghum in different sowing times, a group of trials was set up in the experimental field of the Department of Plant Science, Universidade Federal de Viçosa, Minas Gerais State, Brazil during the 1999/2000 growing season. Eight experiments were used, starting in the first fortnight of October 1999 through May 2000. Each experiment was arranged in randomized blocks with four replications. The sorghum cultivars used were: AG 2002, BR 501, BR 506, BR 601, BR 602 and BR 700 (forage), AG 2005E and Massa 03 (dual purpose) and AG 2501C and BR 800 (cutting and grazing). The phenological stages (floral differentiation, flowering and maturation) for each cultivar were evaluated for each sowing time. It was concluded that the cultivars AG 2002, BR 501, BR 601, BR 602, and BR 700 were sensitive to photoperiod, while AG 2005E, AG 2501C, BR 506, BRS 800, and Massa 03 were insensitive. The temperature decrease caused a delay in the phenological development for all cultivars, while the increaseadvanced the cycle.

KEY-WORDS: Sorghum bicolor; photoperiod; cultivar; forage; temperature.