Some metabolites and embryo growth of primed tobacco (Nicotiana tabacum L. cv. ‘KFI09’) seeds were observed during priming. The seeds were primed at 15 and 25~circC for 1, 2, 3, 5, 10 and 15 days in a -0.8 MPa polyethylene glycol 6000 (PEG) solution. The time to 50% seed germination (T50 ) was greatly reduced when the seeds were primed at 25~circC when compared with 15~circC . The α -amylase activity and sugars and amino acid contents in the seeds primed at 25~circC greatly increased, while α -amylase activity was similar, and sugar and amino acid contents increased slightly in the seeds primed at 15~circC . When the seeds were primed at 25~circC , growth of the embryo which was enclosed by endosperm was detected, while the endosperm became thinner as the priming duration was extended.d