including the การคืนสภาพ condition to test pollen viability, the germination result is much worse than the real value. And this also reminds us of cautious using of in vitro germination method to compare pollen viability. In plants, it has proved that controlled การคืนสภาพ allows the กระดาษแก้วs in the plasma membrane bilayer to go through phase transition before being exposed to bulkwater (Crowe et al., 1989). Thus the change of การคืนสภาพ condi-tion probably suggest the transition of physiological state of plasmamembrane which is the mechanism of early change of pollen viability.