景天属植物需水特性及节水灌溉研究

Study on Water Requirement Characteristics and Water-saving Irrigation in Sedum Plants

[目的]研究景天属植物的耗水规律及需水特征，为景天属植物在北方干旱地区进行抗旱节水生态建设提供理论依据。[方法]以草地早熟禾为对照，研究了德景天、八宝景天、三七景天、卧茎景天4种景天属植物的耗水规律和需水特性。[结果]浇水后进行控水，4种景天属植物及草地早熟禾的土壤水分在控水约10d内大量蒸发，土壤相对含水量下降了60％左右。土壤已达重度干旱；4种景天属植物及草地早熟禾的日蒸散量随土壤水分的减少而减少，在控水约10d内大量蒸散，之后日蒸散量极小。4种景天植物的年蒸散量为177．09～247．22kg／m2，草地早熟禾年蒸散量为811．05kg／m2，当地年降雨量为474．50kg/m2，理论上4种景天植物均无需灌溉，草地早熟禾需年补充水分336．55kg／m2、年浇水10次；园林绿化实践中4种景天属植物的浇水应为2次／年，草地早熟禾的浇水应为12次／年。[结论]景天属植物抗旱性极强，能够耐受极端干旱环境而保持正常生长和景观，从而实现节水灌溉。

[ Objective ] To study water consumption law and water requirement characteristics of Sedum plants, and provide theoretical basis for drought resistance and water saving in northern drought area. [ Method] Water consumption pattern and water requirement characteristics of Sedum plants（Sedum hybridum, Sedum spectabile, Sedum aizoon, Sedum sarmentosum ） were studied with Kentucky bluegrass as comparison. [ Result ] The results showed that： In the course of without watering after watering fully, soil water evaporated largely in about ten days, soil relative water content declined about 60% and soil was in severe drought for four Sedum plants and Kentucky bluegrass. Their daily evapotrans- piration decreased with decrease of soil water, water in soil and plants evapotranspired largely in about ten days but evapotranspired fewer and fewer after ten days. Annual evapotranspiration of four Sedum plants was 177.09 - 247.22 kg/m2 and annual evapotranspiratiou of Kentucky bluegrass was 811.05 kg/m2, local rainfall capacity was 474.50 kg/m2. Accordingly, four Sedum plants had no demand for watering in a year and water demand of Kentucky bluegrass was 336.55 kg/m2 by watering ten times theoretically. While in greening practice, watering for Sedum plants should be two times yearly and twelve times yearly for Kentucky bluegrass. [ Conclusion] Sedum plants realized water-saving irrigation because their super strong resistance to drought and they had characteristics to survive normally in severe drought conditions for longer time.