Impact of water stress on seed germination and seedling growth of Cynodon dactylon

Seeds of Cynodon dactylon were treated by simulation of soil water potential gradient(-0.2——1.0 MPa) of the different concentrations of hypertonic solution polyethylene glycol(PEG-6000) to investigate effects of water stress on its germination.Germination time,germination percentage,relative germination rate,germination potential,and germination index under different water stress were recorded and analyzed.The results showed that as water stress aggravated,seed germination and seedling growth were inhibited more,the germination percentage,germination potential,the shoot and root's length and the number of leaves and roots were decreased,while the relative germination rate was increased at first but then decreased.In early stage,germination of C.dactylon seeds were affected seriously by water stress environment and its germination time was delayed ranging from 1 to 7 d.The establishment of linear regression equation(y=72.621x2+151.58x+83.05)of seed germination under water stress predicted the drought tolerance critical value is-0.25 MPa.