CHANGES IN HORMONE CONTENT OF PANAX-QUINQUEFOLIUM SEEDS DURING STRATIFICATION

The changes in hormone contents of Panax quinquefolium seeds during th e after-ripening period under controlled stratification conditions wer e investigated. The seeds were stratified in sequence at 18-20 degrees C for 80 d, at 8-13 degrees C for 54 d and at 0-5 degrees C for 88 d. The water content of the stratified medium (sand) was kept at about 1 0%. Gibberellin (GA(3)) and indole-3-acetic acid (IAA) contents in the endosperm were very low at the beginning of stratification, then incr eased slowly to reach a small peak on day 164 and day 144, respectivel y, and finally both increased remarkably by day 198. The changes in th e GA(3) and IAA contents in the embryo were similar to those in the en dosperm. Zeatin might be responsible for cell division of the embryo o f the seeds. The changing pattern of zeatin content in both the embryo and the endosperm was low-high-low, which corresponded to the changin g pattern of the embryo growth rate. Abscisic acid (ABA) concentration s in both the embryo and the endosperm remained high before chilling ( 0-5 degrees C); and dropped to very low values at the end of stratific ation. The drop in ABA contents might be due to the effect of low temp erature during stratification.