The dynamics of indole‐3‐acetic acid in Acer platanoides seeds during stratification and germination

Abstract

During stratification at 5°C indole‐3‐acetic acid (IAA) levels in embryos of Acer platanoides decreased during the early stages but subsequently increased again throughout the remainder of a 144 day period. The reduction in IAA levels in embryos of fruits stored at 17°C was even more pronounced, and in addition, no increase was observed after longer storage periods at this temperature, the levels of IAA remaining very low. Germination in seeds maintained at 5°C was not observed until after 120 days or longer, but germination potential increased at an earlier stage, as shown by the fact that seeds transferred to 20°C gave appreciable increases in germination after much shorter chilling periods. Endogenous IAA levels in embryos from seeds transferred to 20°C after a chilling period, long enough to break dormancy, increased within 24 h, i.e. before visible germination, to levels similar to those observed in embryos from seeds chilled continuously for 144 days. Embryos from seeds chilled for 120 days, i.e. when the samples already showed visible germination and when the endogenous IAA content was already high, showed no further increase in endogenous IAA during a three day incubation at 20°C. None of the treatments employed was effective in inducing germination of seeds or embryos from fruits stored at 17°C.