Effect of Sucrose Concentration on Seed Settling Rate and Germination Rate in Toxicodendron vernicifluum Seed Sorting

Abstract

The recent rapid increase in the demand for tree lacquer from Toxicodendron vernicifluum for national treasure has made it essential to cultivate T. vernicifluum forests and increase the production of its seedlings. The seeds of T. vernicifluum are dormant and have a low germination rate. Moreover, their germination rates vary even after dormancy-breaking treatments. The presence of empty seeds may be one possible cause, which can be tackled via specific gravity sorting with salt water. However, increasing the specific gravity of the solute may improve the selection rate. In this study, sucrose was used as a solute to improve the sorting rate in the specific gravity sorting of T. vernicifluum seeds. The results showed that the sedimentation rate decreased even at sucrose concentrations exceeding a saturated salt solution. This finding suggests that even non-sufficient seeds, which cannot be removed by saltwater sorting, could be removed using this method. Furthermore, the germination rate of the selected T. vernicifluum seeds increased with increased sucrose concentration. Increased germination rates were also observed in seeds settled in sucrose solutions with a specific gravity higher than that of saturated salt solutions, suggesting that the settled seeds in saturated brine were empty.