Characteristics of Sugarcane Varieties Related to the Number of Undamaged Buds per Unit Weight of Setts after Mechanical Harvesting for Billet Planting

Abstract

Considerable labor-saving in sugarcane planting work can be expected by introducing the billet planter which plants mechanically-harvested sugarcane setts. However, decrease in germination rate after planting due to physical damage on buds caused by mechanical harvesting is one of the major problems. In this study, characteristics of sugarcane varieties related to the number of undamaged buds after mechanical harvesting were investigated. Our survey on the conditions of the setts of recommended varieties for Kumage-region after mechanical harvesting revealed that 5-10% of buds were lost in all varieties, and that the varietal difference in damage rate in the remaining buds was not clear. On the other hand, the number of undamaged buds was larger in varieties with thinner stem and/or many nodes. Comparison of 2 varieties with different bud dormancy indicated that the germinated buds on standing stalks in the field were more susceptible to physical damage than the ungerminated buds. The number of damaged buds after mechanical harvesting was larger in NiTn18 compared to Harunoogi which had a higher rate of ungerminated buds than NiTn18. Furthermore, the number of damaged buds increased when stalks were detrashed. The results of the present study indicated that varieties with characteristics such as stalk thinness, larger node number, strong bud dormancy and difficulty of detrashing could be an advantage in suppression of mechanically-caused bud damage and in maintenance of undamaged bud number per weight of unit setts after mechanical harvesting.