Effects Of Regulated Deficit Irrigation On Water Consumption,Morphological And Physiological Characteristics Of Cool-season Turf Grass In Semiarid Area

In semiarid areas, saving lawn irrigation water is the most important issue of landscaping. Regulated Deficit Irrigation, in crops, fruits and vegetables, has been proven to increase water use efficiency, save irrigation water, inhibit the vegetative growth without affecting the production. However, the biomass of turf grass is not the goal of turf management, to the opposite, over growth increased management costs. So regulated deficit irrigation technology in turfgrasses irrigation can save water, inhibit turf growth without affecting turf quality and reduce the trimming costs. It is meaningful for saving water and energy in turf management.This study was conducted in the greenhouse with the cool-season turf grass Perennial ryegrass (Lolium perenne L.) varieties Premier and Panterra, Tall fescue (Festuca arundinacea Schreb.) varieties Barlexas and Easy Care, Kentucky bluegrass(Poa pratensis L.) varieties Barvictor and Barrister, which are widely used in semiarid areas and have a better drought-resistance. Water consumption, Physiological, biochemical response and the most optimal irrigation threshold for each grass species were studied. The main conclusions are as follow:(1) Different levels of regulated deficit irrigation produced the stress effect during various periods in arid stage among turf grasses. To be specific, relative soil water content (RSWC) declined slowly; evapotranspiration (ET), aboveground biomass, turf quality (TQ), net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), the fluorescence parameters (Fv/Fm) and leaf relative water content (RWC) decreased; The relative conductivity(EL)increased; The underground biomass, ratio of root to shoot, root activity, chlorophyll content (Chl), leaf water use efficiency (WUE) saw an increase before declined; The intercellular carbon dioxide concentration (Ci) decreased at start, then increased.(2) Whenthe relative soil water content was lower than the lower limit,although the treatments which lower irrigation limit higher than50%FWC (field capacity) caused stress effect to various grasses, it will not cause greater harm. Whilethe treatment whichlower irrigation limit was40%FWC, if the relative soil water content lower than the lower limit, the grass injury was more serious. The extent of stress injury in Panterra was most serious; the Premier, Barvictor, Barrister indicators injury were lighter than Panterra; Barlexas and Easy Care by the stress were relatively light.(3) All varieties of grasses at the end of the drought stage showed severe stress (lower irrigation limit of20%FWC) injury, but recovered rapidly in the physiological function after rehydration except to Pandora.(4) The optimal lower irrigation limit of all grasses is different. Premier, Barvictor and Barrister is40%FWC; Barlexas and Easy Care is20%FWC; Panterra50%FWC. If the lower turf were allowed, the lower limit of irrigation can be appropriately reduced. Specifically, Premier, Barvictor and Barrister can be reduced to20%FWC, Panterra can be reduced to40%FWC, while the Barlexas and Easy Care require further study.The grasses can maintain good turf quality under optimal regulated deficit irrigation conditions. The damage of physiological and biochemical mechanisms in the drought stage can be repaired rapidly after rehydration. In the optimal regulated deficit irrigation conditions, turf grass growth, the amount of irrigation also declined sharply, which can effectively save the irrigation and trim costs in the turf management.