Effects of Growth Substances on Reserve Starch

Abstract

The effect of indoleacetic and naph-thoxyacetic acids upon the hydrolysis of reserve starch was tested, with the following results (1) Lanolin applications (1%), applied for 6 days to tomato cuttings cultured in a sucrose, maltose, lactose, glucose or levulose medium in the dark, brought about a depletion of starch from regions activated by the growth substances. Untreated cuttings had an abundance of starch at the end of the same period. A large amt. of starch, however, was deposited in the endodermal root-caps of primordia induced by the growth substances. (2) 0.02 and 0.002% aqueous solns. of indoleacetic acid inhibited digestion of starch in thin sections (up to 0.5 min.) of tomato and bean stems. (3) A 0.02% soln. of indoleacetic acid, plus or minus sucrose, accelerated the digestion of starch in comparable tissues of bean cuttings. Lower concs. in (2) and (3) were apparently without effect.