Study On Regulated Deficit Irrigation Model Of Cool-season Turf Grass In Lanzhou

The water saving irrigation of lawn has been concerned by more and more people. Regulated deficit irrigation is a good measure of water saving irrigation. At the right time choose a moderate reduction in irrigation and ensure people can accept the turf quality, then the lawn grows slowly, The drought resistance of the lawn was improved in a certain extent, at the same time, reduce the lawn mowing frequency, the maintenance cost and irrigation water. Therefore, it is important to establish the optimal regulated deficit irrigation model for different seasons in Lanzhou area, which is of great significance for the development of the water-saving irrigation system.This study was conducted with the cool-season turf grass Perennial ryegrass(Lolium perenne L.), Tall fescue(Festuca arundinacea Schreb.), Kentucky bluegrass(Poa pratensis L.), White Clover(Trifolium repens L.) which are widely used in Lanzhou has been study in different regulated deficit irrigation and re-water treatment:(control: 70%~80% FWC, lower irrigation limit of treatment 2: 65%~56% FWC, treatment 3: 55%~46% FWC, treatment 4: 45%~36% FWC, treatment 5: 35%~26% FW, treatment 6: 25%~16% FWC, FWC: field moisture capacity). The study explore the water consumption of the lawn in Lanzhou area by measuring evapotranspiration; Analyzing the change of soil moisture, growth index and physiological index, and providing theoretical support for water saving irrigation lawn. The main conclusions are as follow:(1) In the case of adequate irrigation, evapotranspiration(ET) was mainly affected by seasons. Four kinds of turf grass evapotranspiration is the largest in summer, total evapotranspiration of perennial ryegrass, kentucky bluegrass and tall fescue in spring was significantly higher than that in autumn, and there are no significant differences between total evapotranspiration of white clover in spring and in autumn. Under water deficit condition, when the soil relative water content reached treatment 5 and 6 irrigation lower limit, ET of perennial ryegrass, kentucky bluegrasswas significantly lower than control in spring and autumn; was significantly lower than control from treatment 4 to 6 in summer. ET of tall fescue was significantly lower than control from treatment 4 to 6 in spring, summer and autumn. ET of white clover has no significant differences between every treatment and control.(2) In spring and autumn, treatment 2 have no effect on the index of perennial ryegrass and kentucky bluegrass. Treatment 3 and 4 have a significant change on them, treatment 5 and 6 make the index of them more change. Treatment 2 and 3 have no effect on the index of of tall fescue, treatment 3 and 4 have a significant change on it. Treatment 5 and 6 make the index of tall fescue more change, after re-water, the index can not fully recovery. The index of white clover have little change under treatment 2, index changes gradually increased from treatment 3 to 6. When the soil relative water content below treatment 4, the index of white clover is difficult to return to the control level after re-water.(3) Effects of different deficit irrigation treatments on tall fescue and perennial ryegrass in summer is similar to effects in spring and autumn. Effects of different treatments on kentucky bluegrass and white clover in summer is bigger than effects in spring and autumn. In summer, treatment 3 have a significant influence on kentucky bluegrass, but the index can be completely recovery after re-water. Index changes gradually increased from treatment 4 to 6, it is difficult to recovery after re-water. The five treatments except control have a significant effect on white clover. When the soil relative water content below treatment 3, the index of white clover is difficult to return to the control level after re-water.(4) In different seasons, the optimal lowest irrigation limit of four kinds turfgrass: in spring and autumn- perennial ryegrass and kentucky bluegrass is 40% FWC, tall fescue is 30% FWC, white clover is 50% FWC. In summer, perennial ryegrass is 40% FWC, kentucky bluegrass is 50%FWC, tall fescue is 30% FWC, white clover is 60%.