Effect Of Dynamics In Surface Soil Moisture On Turfgrasses Seeds Germination Under Subsurface Drip Irrigation

Subsurface drip irrigation is applied to lawn, which has some advantages about more efficient water use and decreased energy costs, long system longevity and has no effect on surface manage and activity. However, using direct seeding method on lawn, the shallow sowing depth could limit soil water to spreading from root zone to soil surface under subsurface drip irrigation, which directly affects the turfgrass seed germination and leads to planting lawn more slowly. Taking three cool-season turfgrasses seeds and surface soil as the study object, discussed the impact of subsurface drip irrigation(SDI) on the relationship about seed germination and surface soil moisture of changes.Taking three turfgrass as the objects, this study simulated subsurface drip irrigation by limiting the irrigation quantity, which discussed the changes of seed imbibition and germination under 10 water gradients. Results showed that a seed germination function was derived and validated by measured data which comes from the seeds of three turfgrasses. The processes of seed germination were rapid in the initial stage and slow in the later stage, then stable in the end. When irrigation quantity increased to a certain extent, the cumulative germination rate could achieve the maximum value, but when exceeded this boundary, it would inhibit the seed germination. Among the three turfgrasses, perennial ryegrass was most sensitive to water, so its cumulative seed germination rate firstly reaches steady state, while Kentucky bluegrass was the slowest. The parsimonious model was developed to calibrate the water consumption and drive them with estimating the optimal regression equations of germination rate.Pot experiment considered the different characteristics of irrigation and combined with the optimal water, discussed the change of surface soil moisture with 2 water gradient. The results showed the difference of surface soil moisture under different irrigation or water treatment. On the start point, the soil moisture change rapid, but in the irrigation stable period the depth of emitter did not affect soil moisture.The result can be quantified description the relationship between external water variation and germination rate in the process of germination and contributed to improved predictions of the optimal fitting curves of the germination in a range of water. So it is used to estimate surface soil moisture and improved water use efficiency.