Abstract: Mung bean (Vigna radiata (Linn.) Wilczek) seeds were used as experimental materials.Changes during imbibition of mung bean seeds,and effect of preimbibition on desiccation tolerance and leakage of seeds were studied.Water uptake by seeds did not exhibit a marked “plateau phase” of imbibition.The time and thermal time required for 50% germination of seeds were 11?h and 115 degree days,respectively.Relative leakage from seeds significantly increased at the initial phase of imbibition,and then declined.Water content and survival of mung bean seeds preimbibed for different time,fresh weight of seedling and length of radicle and hypocotyls produced by surviving seeds markedly decreased with increasing dehydration.Desiccation sensitivity of seeds also dramatically increased with increasing preimbibition.Relative leakage of preimbibed seeds slowly increased at the early stage of dehydration,and then rapidly increased;and the longer preimbibition time was,the larger relative leakage increased.These results showed that the desiccation tolerance of preimbibed mung bean seeds was gradually lost by dehydration,and that desiccation sensitivity of imbibed germinative orthodox seeds can serve as a model system for studies of seed recalcitrance.

Key words: Vigna radiata seed