Studies on Characteristics of Sugarcane Varieties Related to the Adaptability to Mechanical Billet Harvesting and Billet Planting

To reveal the sugarcane characteristics related to the adaptability to the mechanical harvesting-planting system using a cane harvester and billet planter, we compared the germination numbers (GN) and yields between the plots planted with harvester-prepared (HV) and manually prepared (control) setts of recommended varieties for Kumage-region. In 2017, GN and yields were lower in the HV-sett plots than in the control-sett plots in all varieties. In 2018, without rainfall for 2 weeks after planting, GN were considerably lower in the HV-sett plots than in the control-sett plots. Increase of planted bud numbers improved GN in the HV-sett plots, although the effect was less in the varieties with a larger stalk diameter. At harvest, the stalk numbers and yields were lower in the HV-sett plots, indicating that GN affected the yield through the stalk numbers. When the HV-setts were planted by a billet planter, GN, stalk numbers and yield of the variety ‘Harunoogi’, which showed thinner stalks, larger node numbers and higher germination rate, were highest. Although the variety ‘NiTn18’ showed the smallest GN, the yield was second-highest because of the compensatory tillering. These results indicated that the success of germination was most important in the mechanical harvesting-planting system, and that sugarcane characteristics such as thinner stalk and larger node number which contribute to the increase in bud number per unit weight of HV-setts, as well as higher germination and tillering abilities, were important for the adaptability to the system.