Abstract
In this paper, the optimal harvest time for two harvests per year in forage sugarcane variety, KRFo93-1, was studied. The growth stability and yield productivity were examined in plots harvested in July-May, August-May, September-May and October-May. This experiment was conducted until the 5th ratoon crop for three years. Although there was no significant difference in annual dry matter yield among the four plots, the highest annual dry matter yield of the three-year average was 3.89 kg m-2 both in the August-May and September-May plots. In the 2nd crop of the October-May plot, weeds grew vigorously because the canopy of forage sugarcane was not closed. On the other hand, in the July-May and August-May plots, forage sugarcane controlled weeds because the canopy was closed before the onset of winter. As mentioned above, it is concluded that the August-May plot is the optimal harvest time. The relationship between the growing degree days (GDD, base temperature 14.3°C ) and dry matter yield were also studied to predict the yield. The dry matter yield was expressed by the following regression curve, Y=6.21 ［0.0154exp(−0.00113 X)］ and R2 was 0.892. This regression curve is expected to help in deciding the harvest time of forage sugarcane.
