Impact of cryopreservation freeze-thaw cycles on the viability of medicinal plant seeds
In order to investigate the effects of cryopreservation freeze-thaw cycles on the viability of medicinal plant seeds,mature seeds of three medicinal plants,namely Carthamus tinctorius L.,Zea mays L.and Glycine max(L.)Merr.,were selected as experimental subjects.The viability,germination rate and physiological and biochemical indexes were evaluated by setting different freeze-thaw retention times and frequencies.The results showed that the effects of freeze-thaw retention time and frequency on seed viability and germination rate are not significant,especially for Zea mays L.seeds,which still remain above 90％despite a decrease in germination rate.In addition,the peroxidase and catalase activities of these seeds vary significantly from 0 h to 2 days,and then stabilize,which may be due to the initial impact of the ultra-low temperature freezing stress on the seed capacity of the reactive oxygen species scavenging system.With the prolongation of the retention time,the internal enzyme system of the seeds gradually regain its balance.It is also found that there are no significant changes in malondialdehyde content and conductivity during the freezing and thawing process,which indicate that cryopreservation freeze-thaw cycles do not cause serious damage to the seeds of medicinal plants.It is concluded that the freeze-thaw cycles of liquid nitrogen at ultra-low temperatures have no significant effect on the seed via-bility of normal medicinal plants,which provides theoretical and practical support for the long-term conservation of medici-nal plant germplasm resources.
cryopreservationfreeze-thaw cyclesseeds of medicinal plantsseed viability
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