Effects Of Silicon On Growth And Water Use Efficiency Of Turf-used Tall Fescue(Festuca Arundinacea) Under Salt Habitat

Turf plays an essential role in the urban ecosystem by improving and beautifying the living environment. Continual irrigation is one of the principal measures to maintain healthy and sustainable utilization of turf in the arid and semi-arid regions, consequently, such not only exacerbates the water scarcity in China but also more possibly leads to salinization. Therefore, improving water use efficiency and tolerant ability to salt of turfgrass is an urgently scientific issue in the turf management. At present, water and fertilizer coupling is a key approach to improving water use efficiency and salt tolerance of plants by combining multiple factors instead of single factor contribution. Silicon is the second element in the Earth's crust but available silicon of soil is low. Previous studies indicated that addition of silicon significantly not only improves water use efficiency of some crops and forages but also inhibits the plants'absorption of sodium ions and increases the plants'absorption for phosphorus and potassium, and is not harm to environment. Based on the environmental problems faced by turf management and benefit features of silicon element, the experiments were carried out to determine the response of seed germination, seedling growth, water use efficiency under salt stress to addition of silicon using pot experiments, and main conclusions were drawn as following.Firstly, addition of silicon encouraged the emergence and increased seedling survival rate of tall fescue.Initial time of emergence in tall fescue caused by addition of silicon brought forward two days, shortened the duration of emergence, increased the total seedling number and the seedling survival rate. Total emergence and seedlings survival rate of tall fescue significantly increased with the increase of Si supply (P＜0.05).Secondly, addition of silicon improved the growth of tall fescue and did not affect the texture of the lawn under salt stress.Addition of silicon significantly increased the height, leaf length and its area, and tiller number of plant in tall fescue, but did not affect on leaf width, implying that addition of silicon did not affect the texture of the lawn. This study also indicated that plants biomass had been increased by Si supply and shoots growth of tall fescue was more sensitive than roots growth of tall fescue. According to response of morphological parameter of tall fescue to addition of silicon,0.4 g-kg-1 silicon was better to tall fescue growth when available silicon of soil was 140 mg·kg-1Thirdly, the benefits of silicon to tall fescue growth were regulated by the soil water content, indicating that the response of the emergence, growth of shoots and roots to addition of silicon was different at the different soil water conditions.Addition of silicon did not work when the soil moisture was less than or equaled to 30% of field water holding capacity. Although addition of silicon did not affect the emergence of tall fescue, it increased the roots growth when soil moisture was equal to 45% of field water holding capacity. Application of silicon not only brought forward the initial time of emergence, shortened the duration of emergence, increased the seedling survival rate of tall fescue, but also encouraged the growth of shoots and roots when soil moisture was greater than or equaled to 60% of field water holding capacity.Fourthly, addition of silicon improved the water use efficiency of tall fescue plants when soil moisture was greater than or equaled to 60% of field water holding capacity.Addition of silicon did affect the water use efficiency of tall fescue when soil moisture was less than or equaled to 45% of field water holding capacity. This study indicated that application of silicon significantly increased the water use efficiency of tall fescue by increasing the photosynthetic, and reducing the stomatal conductance and intercellular CO2 concentration in leaves under the salt stress when the soil moisture was greater than or equaled to 60% of field water holding capacity.Fifthly, addition of silicon improved the salt tolerance of tall fescue.Application of silicon increased the photosynthetic rate, chlorophyll content, chlorophyll a/b values, reduced the MDA content and electrical conductivity of leaves, and enhanced the proline content, indicating that silicon increased the photosynthesis, reduced the membrane lipid peroxidation. and improved the salt tolerance of tall fescue. Finally, silicon content of roots was greater than that in shoots in tall fescue, and drought stress reduced the absorptive capacity to silicon of tall fescue.Both the silicon content in roots and shoots increased with the increase of silicon concentration, and they were below 3.0%. Silicon content in roots was double that in shoots. The deposit of silicon in leaves and roots of tall fescue declined under drought stress.