Possible biological control of the armyworm by the harvest mouse Effects of day-length and night temperature on the flowering of sorghum varieties with a dominant thermosensitivity gene

This study aimed to clarify the flowering habit in sorghum varieties with a dominant thermosensitivity gene. The number of days from sowing to floral initiation in four varieties with a dominant thermosensitivity gene (TT and Tt) and two varieties of which flower initiation does not depend strongly on day-length and night temperatures were evaluated under different day-length and temperature conditions. The day-length treatment at 25°C indicated that anything over a 12.5-h day-length has a long day effect on the flowering of the sorghum varieties examined. Under a long day condition of a 12.5-h day-length, floral initiation was accelerated under 30°C/20°C (day/night) conditions, compared to 25°C (constant) conditions in the varieties with a dominant thermosensitivity gene. Under a 15-h day-length, floral initiation was accelerated at night temperatures of 20°C and 15°C instead of at the constant 25°C. These results suggest that floral initiation was accelerated by a night temperature of lower than 20°C, even under long day-length conditions in sorghum varieties with a dominant thermosensitivity gene.