Study On Salt Tolerance Of20Ornamental Grasses Under The Condition Of Seawater Irrigation To Simulate Salt Stress

Ornamental grass with good visual effects and ecological functions is a new type of garden plants. Growth and physiological conditions of seedlings of20ornamental grasses in families Poaceae and Cyperaceae under0(control),25%,50%,75%and100%seawater stress were studied by utilizing seawater irrigation to simulate salt stress experiment. These20ornamental grasses’salt tolerance was classified according to plants’average death rate and cluster analysis results of related growth indicators and physiological indicators under25%seawater stress.The results are as follows:K With rising of seawater concentration,height,canopy width (tiller number),biomass,root/shoot ratio and chlorophyll relative content(chlorophyll content)of20ornamental grasses all show downward trends,while the percentage of withered leaves all show upward trends.And the higher salt tolerance plants have a smaller variation scopes.2、With rising of seawater concentration, relative electrical conductivity of leaves, MDA content and SOD activity of Achnatherum splendens (Trin.) Nevski and8Carex species all show upward trends; relative electrical conductivity of leaves and MDA content of the ornamental grass taxa with high salt tolerance have smaller variation scopes,while the SOD activity varies larger.3、With rising of seawater concentration.the net photosynthetic rate.stomatal conductance and transpiration rate of Achnatherum splendens (Trin.) Nevski, Eragrostis spectabilis (Pursh) Steud. and Carex leiorhyncha C. A. Mey. all show downward trends, while the intercellular CO2concentration all show upward trends, and the variation scopes of the photosynthetic indicators are sized down as follows: Carex leiorhyncha C. A. Mey.> Eragrostis spectabilis (Pursh) Steud.> Achnatherum splendens (Trin.) Nevski.4、According to the average death rate of plants in the end of the experiment, the salt tolerance of 20ornamental grasses can be divided into5grades:the average death rate of Achmatherum splendens (Trin.) Nevski. is zero with the highest salt tolerance; the average death rates of Penniseium alopecuroides (L.) Spreng.. Eragroslis ferruginea (Thunb.) Beauv, E. spectabilis (Pursh) Steud., Miscanthus sinensis "Zebrinus’ and M. sinensis’Gracillimus’are below25%with higher salt tolerance; the average death rates of C. leiorhyncha C. A. Mey., C. neurocarpa Maxim., C. lanceolata Boott, C. leucochlora Bge., Miscanthus sacchariflorus (Maxim.) Hack., M. sinensis’Yaku Jima’, M. sinensis "Variegatus" and M. sinensis "Malepartus" are between25%to50%with middle salt tolerance; the average death rates of C. muskingumensis "Oehme". C. humilis Leyss. var. nana, Calamagrostis brachytricha Steud. and M. sinensis’Morning light’are between50%to75%with lower salt tolerance: the average death rates of C. hancockianu Maxim, and C. for/icula Franch. are above75%with lowest salt tolerance.5、Under these experimental conditions.the classification of20ornamental grasses" salt tolerance is as follows:A. splendens is the highest:C. leiorhyncha. C. neurocarpa, C. lanceolata. E. ferruginea. E. spectabilis. P. alopecuroides. M. sinensis "Gracillimus" and M. sinensis’Zebrinus’are higher; C. humilis. C. leucochlora, M. sacchariflorus. M. sinensis "Morning light" and M sinensis’Yaku Jima’are middle; C. inuskingiunensis. C. hancockiana.C. brachylricha. M. sinensis "Variegatus" and M. sinensis ’Malepartus’are lower; C. forficula is the lowest.The research is the first attempt to utilize seawater irrigation to simulate salt stress condition to conduct the salt tolerance assessment of the plants. A. splendens and other8ornamental grasses with higher salt tolerance are chosen through preliminary screening, which provides a reference for improving the ecological environment in the coastal saline soil area.