Effects of Stevioside and Its Relative Compounds on Growth of Rice and Lettuce Seedlings

Abstract

Biological activities of steviol-glucosides such as stevioside, rebaudioside B, stevioside A₃, dulcoside A and rebaudioside C were tested by the rice seedling assay using one usual variety, Nihonbare and one dwarf variety, Tan-ginbozu. At the dosage of 100μM by root treatment method, 6 tested compounds were active in the leaf sheath elongation of Tanginbozu. But normal variety, Nihonbare showed no response to all glucoside at dosage tested. On the other hand, treatment of coleoptile application method indicated that a degree of activity of glucoside for the Tan-ginbozu is approximately the same as that by the root treatment method, at a dosage of 10μg per plant. These compounds also promoted the elongation of the hypocotyl and radicle of lettuce at concentration higher than 200μM. However, growth response to glucoside in seedling tests was at lower activity than that by steviol, aglycone of them.