Physiological characteristics on seed germination and seedlings of Perilla frutescens under stimulated drought stress

Physiological characteristics of seed germination and seedlings of Perilla frutescens under polyethylene glycol 6000( PEG- 6000) as drought stress stimulation was investigated. 3 treatments of PEG- 6000 concentrations of light drought stress( 2. 5%,5. 0% and 10%),medium drought stress( 15% and 20%) and heavy drought stress( 25%) were used to soak the seeds and seedlings. Results showed that Gr( germination rate),Gi( germination index),Vi( germination vigor index),Gp( germination potential) and Vr( vitality rate) of seeds decreased gradually along with the increment of PEG- 6000 concentrations,but there was no significant difference in light drought stress( P 0. 05). Gr was significantly decreased in medium drought stress( P 0. 05). In heavy drought stress seeds did not germinate. Along with the increment of drought,stem length and fresh weight were markedly decreased,while the main root length increased initially and then decreased. Activity of SOD,POD and CAT also increased initially and then decreased,but MDA content increased continuously. These finding indicated that seed germination and seedling growth of P. frutescens were significantly inhibited by drought stress. Meanwhile the seedlings demonstrated certain adaptability to drought stress via physiological changes.