Changes in endogenous hormone contents of pear stock (Pyrus betulaefolia Bge. and Pyrus calleryana Dcne.) seeds during cold stratification
In this study, changes in endogenous hormone contents of pear stock seeds during cold stratification were investigated. Abscisic acid (ABA) content decreased with increase in the periods of stratification of pear stock seeds. However, gibberellic acid (GA) and indole-3-acetic acid (IAA) contents of Pyrus betulaefolia and Pyrus calleryana gradually increased and then decreased, and the GA and IAA contents of P. betulaefolia and P. calleryana seeds reached maximum level at 40 and 50 days, respectively. The results suggest that ABA and GA had regulatory roles in dormancy release, but IAA seems to be involved in the germination process.
Key words: Pear stock seed, cold stratification, hormone.