Salt-tolerant Turfgrasses Selection And A Preliminary Study On The Effect Of Organic Silicon Addition

Soil salinization and secondary salinization are one of the limiting factors that restrict the growth and successful planting of turfgrass along the beach,the assessment and screening of salt-resistant grass species has become an integral part of the saline soil improvement and greening project.Evaluation was carried out with 86commercial varieties of grasses involved in 12 species,mainly gramineae,pass 1)TP germination method,300mmol·L^-11 NaCl plus 50 mmol·L^-11 MgSO₄ salt stress treatments as well as distilled water as control were set aimed to preliminary determination their salt tolerance differences among different grass species tested.2)Potted method,NaCl concentration of 100mmol·L^-11 plus MgSO₄ concentration of17mmol·L^-1,NaCl concentration of 200mmol·L^-11 plus MgSO₄ concentration of33mmol·L^-1,NaCl concentration of 300mmol·L^-11 plus MgSO₄ concentration of50mmol·L^-11 totally four salt stresses were set to screening out subjects whose salt-tolerance were moderate or higher among assessed varieties.Varieties of salt tolerance types were determined through the morphological growth changes of seedlings and the electric conducting of isolated leaf cell membrane of different salt tolerance grass species previous selected.Physiological characteristics and growth mechanism of different salt-tolerant strains will be revealed.3)Daejeon test,4salinized plots including conductivity of 100ms·s^-1,300ms·s^-1,500ms·s^-11 and2000ms·s^-11 with grass crumbs covering the surface of soil as potted water for comparison,to evaluate the agronomic characteristics,turf related traits and adaptation to soil environmental changes for those candidated varieties whose salt-tolerance were better than others with the goal to study the adaptability of salt-tolerant grass species in coastal-based salt land,and the lawn cultivation model to improve the quality of the saline-alkali lawn was explored at the same time.4)1/2Hoagland nutritional hydroponic spout,the exogenous silicone addition experiment was carried out on the Lolium perenne cv.γwhich was characterized by highest salt-tolerance and NaCl concentration of 300mmol·L^-11 plus MgSO₄ concentration of50mmol·L^-11 salt-stress treatments were set with distilled water as control,both of the2 salt treatments,0,1,2,3,4,5mmol·L^-11 6 silicon fertilizer[with Tetraethyl orthosilicate as a silicone source]level were applied includes leaf spray（ssi）and solution addition（SSI）two applying method.To investigate the response of the above-ground and underground parts of L.perenne cv.γunder severe salt stress to different concentrations of silica levels,and to screen out the most appropriate silicone concentration and addition methods to improve the salt resistance of L.perenne cv.γ.The main results were as follows:1.Research on TP germination method shows:the germination time of tested turfgrasses seeds were significantly prolonged under 300mmol·L^-11 NaCl plus50mmol·L^-11 MgSO₄ salt stress,reduced the germination rate,germination index of turfgrass seeds,and inhibited the growth of grass seedlings and root systems while total length of the root system,the total surface area of the root system and the average diameter of the root system was promoted in some salt-tolerant varieties under 300mmol·L^-11 NaCl plus 50mmol·L^-11 MgSO₄ salt stress.12 grass species with higher salt-tolerance were screened ou under severe salt stress through corresponding trials.The three grass species with higher salt resistance were Lolium perenne,Festuca arundinacea and Festuca sinensis.Amongst Lolium perenne,γ,Gentry,Barlennium etc varieties were stronger in salt tolerance.Among Festuca spp.Cultivars of Fire Phoenix 2,Barvado II,Cold were stronger in salt tolerance.Among Trifolium spp.,higher salt tolerance cultivar in super-Huia in Trifolium repens,Dolly in Trifolium pratasis,and cherry in Trifolium incarnatum,respectively.Among Poa pratensis,higher salt tolerance varieties were Merit,Baron and Blue chip.Cultivars such as A-1,Kromi BT,Impala and Highland were higher in salt tolerance for Agrostis spp.2.Potted studies show:turfgrass length,seedling length,leaf width,plant height,lawn quality,root total length,root total surface area,side root number as a whole showed the trend of gradual declined with the salt concentration increasing under salt stress of 100mmol·L^-11 NaCl plus 17mmol·L^-11 MgSO₄ to 300mmol·L^-11 NaCl plus50mmol·L^-11 MgSO₄ salinity gradients,while the average diameter of the root system increased in the majority of tested varieties.The 4 perennial turfgrasses with higher salt-tolerance varieties are L.perenne cv.γ,F.arundinacea cv.Barvado II,Agrostis cv.A-1,and P.pratensis cv.Merit.3.The Daejeon test study shows:L.perenne cv.γis the most suitable grass variety for sowing in Nan tong coastal saline-alkali land,followed by F.arundinacea cv.Barvado II,laying grass chips is also a better measure to improve the growth of turfgrasses under the salty soil environment conditions.In productive practice,the plant with salt-tolerant grass species-L.perenne,F.arundinacea and other species which established lawn with faster speed combined with laying grass crumb layer can achieve a deep and long-lasting reduction of soil surface moisture evaporation,improve soil surface moisture,prevent soil secondary salinization and reduce soil surface salinization under irrigation.Combined with the performance of different grass species in plots experiment under 500ms·s^-11 saline stress,ranking of 4turfgrasses species with salt-tolerant were:L.perenne cv.γ>F.arundinacea cv.Barvado II>P.pratensis cv.Merit>Agrostis cv.A-1.4.1/2 Hoagland nutritional hydroponic spout study:the ration of Na⁺/K⁺,malondialdehydecontent,and proline content in salt spray treatment decreased significantly under 300mmol·L^-11 NaCl plus 50mmol·L^-11 MgSO₄ salt stress compared to the solution addition treatment.Among tested indexes,average diameter of the stem,leaf width,above-ground and underground biomass,and chlorophyll content increase in a great margin.Foliar spraying of silicone was better than solution addition for L.perenne cv.γto promoting seedlings and root growth,improving osmotic adjustment ability,ameliorating the ability to regulate ion balance,and improving the photosynthesis.Solution addition treatment is the best hydroponic measure to improve the salt tolerance of L.perenne cv.γ.Under salt stress,the leaf surface sprayed 4,5mmol·L^-11 concentration of silicone can improve the chlorophyll content of L.perenne cv.γ,reduce the content of chlorophyll malondialdehyde,proline content and the above-ground biomass and the ratio of Na⁺:K⁺.It was the optimal spray concentration to improve salt tolerance for L.pernnne cv.γin the coastal areas.