Changes in Auxin, Germination Inhibitors, Gibberellins, and Cytokinins during the Breaking of Seed Dormancy in Fagus sylvatica

Abstract

Studies on the effect of constant chilling temperature of 4 °C and normal fluctuating temperatures out-of-doors on germinating percentage and endogenous IAA, ABA, gibberellins and cytokinins during the breaking of dormancy of Fagus sylvatica seeds was investigated. Dormant seeds showed 40 and 64 per cent germination after 12 weeks stratification at constant chilling temperature and normal fluctuating temperatures, respectively. Marked increase in IAA levels occurred as a result of both treatments. The increase in IAA was found to be 64 per cent greater at normal fluctuating temperatures than at constant chilling temperature after 12 weeks stratification. The results also showed an equal loss in endogenous ABA after 12 weeks stratification at both treatments. Moreover, a marked increase in gibberellin-like activity at both treatments was found to be almost 75 per cent more at normal fluctuating temperatures than at constant chilling temperature after 12 weeks stratification. The results also showed a high yield in the butano soluble cytokinins with both treatments. The increase in cytokinins was found to be 50 per cent more at normal fluctuating temperatures than at constant chilling temperature.