Research On Evapotranspiration And Water-saving Irrigation Of Different Ecological Types Of Turfgrass

Beijing is a city of extreme water scarcity, shortage of water resources has seriouslyhampered the sustainable development of cities. Be used as a garden lawn, turf grass’s hugewater consumption has caused tremendous pressure to the city’s water utilization.Therefore, evapotranspiration and water-saving irrigation research of turf grass is ofcrucial importance for urban landscape water conservation.This paper would study the following three aspects: First, the evapotranspiration offestuca arundinacea, carex leucochlora, buffalo dactyloides are measured with large-scalelysimeter, and these three turf grass evapotranspiration comparative analysis are determined;Second, evapotranspiration of festuca arundinacea is measured with lysimeter as the standard,analyze and compare the reference evapotranspiration caculated by4models with the standard.And then regression analysis is used to evaluate the model and appropriate forecasting modelapplied in Beijing is selected. Meanwhile, the feasibility of carex leucochlora as a referencecrop would be evaluated; Third, growth and physiology changes of festuca arundinacea underdifferent water conditions are studied by the means of pot-weighing.The results indicated that:1. There emerged typical bimodal curve of ET of festuca arundinacea, buffalodactyloides and carex leucochlora in growing season, the highest evapotranspiration showed inMay and August. From April to October, the total amounted evapotranspiration of festucaarundinacea, carex leucochlora, buffalo dactyloides were respectively629.85mm,556.26mmand543.63mm.2. According to different time scales set in Reference evapotranspiration model, thereexisted different applicability in Beijing region. Among these four models:Under month scale, for Priestley-Taylor model, the consistency index is0.91, the highest,root mean square error (RMSE) was0.54, the smallest, the correlation coefficient R2is as small as0.72, so all the parameters showed that the applicability of the model was perfect, and thefitting formula is ETPT=0.7ETly+24.43.Under day scale, for FAO56Penman-Monteith model, the consistency index of is as highas0.86, root mean square error RMSE was1.17, the correlation coefficient R2is0.73, thehighest, so all the parameters illustrated that the applicability of the model was perfect, and thefitting formula is ETFAO-PM=0.69ETly+1.06.Under hour scale, in sunny windy weather, consistency index of FAO56Penman-Monteith is0.95,the highest, correlation coefficient R2is0.97, the second highest, root meansquare error (RMSE) is1.17, the smallest; in sunny windless weather, the correlationcoefficient of FAO56Penman-Monteith model and consistency index are0.83and0.94, thehighest, root mean square error (RMSE) is0.1, the minimum; in cloudy windy weather, theconsistency index of FAO56Penman-Monteith model is0.9, the highest, correlationcoefficient R2is0.66,the second highest, root mean square error (RMSE) is0.1, the smallest.In all three weather conditions, FAO56Penman-Monteith can keep good applicability.The carex leucochlora cannot be used as a reference crop, the regression equation is y=0.939x-0.353. The crop coefficients of carex leucochlora were1.15,1.14,0.88,0.68,0.98,0.59,and0.95, respectively; the crop coefficients of buffalo dactyloides were0.84,1.03,0.89,0.73,1.04,0.76, and0.74, respectively.3. Deficit irrigation have an impact on the growth and physiology of Carex leucochlora,with the deficit deepen and the treatments prolong, soil water potential and soil water contentdecreased significantly, under25%ETc water potential and soil water content is reduced to-79.5±1.3kPa,18.3±1.1%; leaf water potential decreased significantly from-1.37±0.11MPato-2.30±0.16MPa; the stomatal conductance, net photosynthetic rate and transpiration ratedecreased significantly, water use efficiency improved significantly; the malondialdehydecontent is a significant increase compared with the control; plant height, crown, SPAD valueof leaves, tillers, leaf dry weight, root dry weight were significantly decreased, root to shootratio increased. Even if75%ETc of deficit irrigation also had a significant impact on growth and physiology, indicating that Carex leucochlora, with the deficit deepen and the treatmentsprolong, soil water potential and soil water content decris sensitive to moisture. However,plants grew normally under all the treatmens and did not show victim symptoms, reflectingstrong adaptability of Carex leucochlora on the water.In conclusion, From April to October, the total amounted evapotranspiration of festucaarundinacea, carex leucochlora, buffalo dactyloides were respectively629.85mm,556.26mmand543.63mm. In Beijing region, Priestley-Taylor model is the best applicability undermonth scale; FAO56Penman-Monteith model is the best applicability under day and hour scale.Deficit irrigation have an impact on the growth and physiology of Carex leucochlora, butall the processing plants are under normal growth. This study results for water saving irrigationquantity provide technical guidance.