The growth and yield of forage sugarcane variety, “shimanoushie”, under the two harvests per year system with different harvest times in the Amami region of Kagoshima prefecture

Abstract

In this paper, the optimal harvest time under the two harvests per year system for forage sugarcane variety, “Shimanoushie”, was examined in the Amami region of Kagoshima prefecture. The growth stability and yield productivity using the two harvests per year system were examined in the plots harvested in April and July (AJ), May and August (MA) or June and September (JS). The two-year average value of the annual dry matter yield was 4.05, 4.12, 3.45 kg m–2in the AJ, MA and JS plots, respectively. The yield was significantly lower in the JS plot than in either the AJ or MA plot. Heavy lodging and damage to crops by field mice were seen in the crop harvested in April in the AJ plot. The dry matter ratio of the crop harvested in June in the JS plot was very low and not suitable for silage. The vegetative cover rate by the ratoon crop in early growth stage was significantly correlated with the mean temperature, and it was high in the post-crops of June harvest in the JS plot and of July harvest in the AJ plot. On the other hand, the rate was low in the post-crops of September harvest in the JS plot during the temperature was low, and the growth competition with weeds was concern. It is concluded that harvesting in May and August is optimal in the two harvests per year system in the Amami region.