Effect of Re-Drying and Storage after 10°C Wet Treatment on Germination and Growth of Five Eustoma grandiflorum (Raf.) Shinn Cultivars

In Eustoma (Eustoma grandiflorum (Raf.) Shinn) cultivation in southwestern Japan, cold imbibition treatment of seeds is important to accelerate bolting and flowering of seedlings grown in the summer season. In order to facilitate the handling of cold imbibed seeds, re-drying treatment (RDT) after wet treatment at 10°C for 35 days in dark conditions (WT10°C) is considered to be an essential technique. The investigation of five Eustoma cultivars ‘Exe Lavender’, ‘Orb Snow’, ‘Philia Lavender’ , ‘Dure Lavender’ and ‘Exe Light Pink’ was to find the germinability and the growth characteristics of Eustoma when re-drying and storage at 10°C for 30 days were applied immedietely after ending the WT10°C. The results showed that germination and growth responses differed among Eustoma cultivars. RDT seeds and non- RDT seeds of ‘Exe Lavender’, ‘Orb Snow’ and ‘Philia Lavender’ had a similar germination rate. However, germination rate of RDT seeds in ‘Dure Lavender’ and ‘Exe Light Pink’ was lower than that of non-RDT seeds. There was no significant difference in cut-flower quality grown from RDT and non-RDT among ‘Exe Lavender’, ‘Orb Snow’ and ‘Dure Lavender’. However, bolting and flowering rate of RDT in ‘Dure Lavender’ and ‘Exe Light Pink’ were lower than those of non-RDT. This suggested that it might not be useful to apply RDT after the cold-wet treatment of Eustoma seed due to lower germination or bolting rates in some cultivars. Further investigation of cold-wet exposure and dehydrating conditions is required to establish RDT procedures for Eustoma cultivars.