Evapotranspiration And Water-saving Irrigation Of Groundcover Plants In Common Use Of Beijing Landscape

Beijing lacks water seriously, and landscape greenlands consume plenty of water every year. ET of sixteen groundcover plants were researched at 100%ETc, 75%ETc, 50%ETc, 25%ETc irrigation levels by means of mini-lysimeter-weight and mini-lysimeter-TDR methods, based on ET feedback irrigation in 2006.Water-saving irrigation was suggested according to their growth at different irrigation levels, conducting landscape irrigation.Under full irrigation condition (100%ETc), the total ET of these sixteen plants from June to October was: Sedum spectabile 161.38mm, Ranunculus japonicus 168.84mm, Chrysanthemum morifolium 177.48mm, Iris tectorum 186.90mm, Iris lactea var. chinensis 207.16mm, Rosa chinensis 'Mannheim'319.47mm, Hemerocallis fulva 332.41mm, Festuca glauca 333.49mm, Gaillardia aristata 340.47mm, Viola philippica 394.84mm, Dianthus chinensis 432.61mm, Duchesnea indica 474.94mm, Parthenocissus quinquefolia 493.94mm, Calamagrostis brachytricha 524.02mm, Stipa tenuissima 642.26mm, Arundinella hirta 812.84mm. Combining rain fall of the experiment site in 2006, the total necessary irrigation amount of the sixteen groundcover plants from June to October was 48.49mm～440.80mm. Arundinella hirta and Stipa tenuissima needed irrigation in July and August, and all the sixteen plants needed irrigation in September and October.The reference ET (ET₀) of each month in 2006 was computed by Penman-Monteith equation, applying meteorologic data from the weather station at the experiment site. ETpan was obtained from the evaporation pan. So the crop coefficient Kc in 2006 was gotten with 0.31～1.55, and the water requirement coefficient a was 0.45～2.27.According to growth of the plants under different irrigation, considering water-saving irrigation and landscape ornament both, the sixteen groundcover plants were classified into three groups: 1) Full irrigation (100%ETc): Viola philippica and Duchesnea indica ;2) Light control irrigation (75%ETc): Hemerocallis fulva, Dianthus chinensis, Gaillardia aristata, Chrysanthemum morifolium, Ranunculus japonicus, Arundinella hirta, Stipa tenuissima, Calamagrostis brachytricha, Festuca glauca, Parthenocissus quinquefolia;3) Deep control irrigation(50%ETc): Iris lactea van chinensis, Iris tectorum, Rosa 'Mannheim', Sedum spectabile. Then, on the basis of this result, applying the values of Kc and a above, according to the meteorologic data of different years, the water amount needed for full irrigation and water-saving irrigation can be calculated.