Studies on the hawthorn (Crataegus azarollusL.): II. Changes in abscisic acid content during cold stratification in relation to seed germination

SummaryThe effect of various periods of cold stratification (0,20,40,60,80,100 and 120 days) on the content of endogenous abscisic acid (ABA) and the germination of the hawthorn Crataegus azarollus L. was investigated. The results indicated that cold stratification reduced free and bound ABA contents of the seeds and their endocarps. A sharp decline in ABA was observed during the first 20 days, after which the decline was gradual. Even though cold stratification for 100 and 120 days significantly improved germination percentage over the other periods, the percentage is considered low. The results suggest that a high germination percentage with Crataegus azarollus L. seeds might be obtained if stratification extended for more than 120 days, during which time a considerable increase in endogenous growth promoting hormones would be expected.