Application of Gibberellin to Potato Seed Tubers Enhances the Yield of Small Tubers

In potato production, there is an increasing demand for smaller seed tubers. Dense plant cultivation or heat shock treatment is considered to produce small tubers. However, utilization of these methods is limited because of the high cost and the unstable effect. Therefore, in this study, we investigated whether small tubers can be efficiently produced by treatment of seed tubers with gibberellin (GA) using two different varieties. Application of GA increased the number of stems and yield of small tubers in both varieties. However, there was a significant difference in the response to GA treatment with the variety in various growth characteristics. The results suggested that the susceptibility to exogenous GA differed with the variety. GA is known to inhibit tuber initiation, and decrease the tuber weight at an early growth stage in highly susceptible varieties. However, in highly susceptible varieties, Application of GA increased the number of tubers at the harvesting period similar to that in less susceptible varieties. These results suggest that the nutrient competition among the tubers at the early growth stage was suppressed by GA treatment in highly susceptible varieties, so that the number of tubers at the harvesting period increased compared with the control. This study revealed that the treatment of seed tubers with GA increases the number of tubers at the harvesting stage in any variety irrespective of the susceptibility to GA.