Effect of re-drying seeds after wet treatment at 10°c on the germination and growth of eustoma grandiflorum (Raf.) shinn

This study was initiated to investigate the effects of wet treatment at 10 degrees C (WT10 degrees C) and subsequent re-drying treatment (RDT) on the germination and growth of Eustoma grandiflorum seeds. Both treatments, WT10 degrees C and RDT, were applied at 10 degrees C under dark conditions. In all the experiments, 'King of Snow', which is one of the major Eustoma cultivars in Japan, was used. When the total number of days exposed to WT10 degrees C and RDT was set to 35 days, the prevention of rosettes and the promotion of growth were dependent on the number of days of WT10 degrees C, and these effects were maintained after RDT. When RDT was applied to the seeds after WT10 degrees C for 35 days, the growth promotion due to WT10 degrees C was maintained regardless of the length of re-drying time from 7 to 28 days; however, the germination rate decreased with RDT. On the other hand, applying RDT after WT10 degrees C for 14 days had no effect on the germination rate; however, the growth promotion was insufficient compared with WT10 degrees C for 28 days. This problem was solved by carrying out a further 14 days of WT10 degrees C after RDT. When the seeds were exposed to WT10 degrees C for 14 days, then re-dried for 7 days, and exposed to WT10 degrees C for a further 14 days, the same growth promotion was achieved as for seeds exposed to WT10 degrees C for 28 days continuously. The above results suggest that the promotion of growth depends on the total number of days of WT10 degrees C regardless of whether these days are continuous or not. Moreover, the growth promotion was maintained after RDT. The results also suggest the possibility that when both the processes of WT10 degrees C and the RDT are carried out by seed companies, growers who have no cooling equipment can produce cut flowers using seedlings grown in the high-temperature season.