Abstract
Sucrose phosphate synthase (SPS) activity of sugarcane internodes was measured in field-grown and greenhouse-grown plants. The concentration of sucrose increased and that of reducing sugars decreased at lower temperatures in plants both in the field and in the greenhouse upon ripening. SPS activity increased in winter and at lower temperatures in the greenhouse. These results indicate that the SPS activity increased under ripening conditions. The sucrose concentration and SPS activity of cv. NiF4 were higher than those of cv. F172 both in autumn and winter in the field. However, the results under the greenhouse conditions did not indicate a clear relationship between the SPS activity and sucrose concentration among the different varieties. Acid invertase (Al) activity, whose physiological function in sugar accumulation is opposite, was considered to play a more important role in the greenhouse. The results of this experiment supported the assumption that the SPS activity is one of the factors that control sugar accumulation in sugarcane.
