不同土壤水势条件下青绿苔草花果期灌水量研究

Irrigation of Carex leucochlora during Flowering and Fruiting Period under Different Soil Water Potentials

青绿苔草(Carex leucochlora Bge.)为新开发的园林草坪地被植物,花果期处于我国北方的春早时期,人工栽植应用时需要灌溉。为解决水资源缺乏与青绿苔草生长之间的矛盾,研究了土壤水势下降至-20,-40,-60和-80 kPa时充分灌溉对青绿苔草的叶水势、光合蒸腾特性、生长情况的影响。结果表明:随着土壤水势由-20 kPa降低到-80 kPa,青绿苔草的叶水势由-1.54 MPa显著下降到-2.50 MPa,气孔导度、胞间CO_2浓度、净光合速率和蒸腾速率也逐步降低,水分利用效率由3.53umol CO_2·mol^(-1)H_2O显著提高到9.23 umol CO_2·mol^(-1)H_2O。经过整个花果期的不同灌溉处理,青绿苔草的株高、冠幅、分蘖数、茎叶干重和根干重随着灌溉点土壤水势的下降而显著降低,但所有处理下植株均生长正常,能保持较好的景观效果。因此,为了节约灌溉用水,在青绿苔草花果期,当土壤水势下降到-80 kPa时灌溉,可比土壤水势下降到-20 kPa时灌溉节约用水32.3%。

Carex leucochlora is a new-developed landscape ground-covering plant. It＇s flowering and fruit- ing period is in the spring drought season in the northern of China. To understand the contradiction be- tween water shortage and the growth of C. leucochlora, the impacts of irrigation on the leaf water poten- tial, photosynthesis and transpiration characteristics, and growth of C. leucochlora were investigated as soil water potentials decreased to --20, --40, --60 and --80 kPa. Results showed that the leaf water po- tential of C. leucochlora decreased significantly from -1.54 to -2.50 MPa, and the stomatal conduct- ance, intercellular CO2 concentration, net photosynthesis rate and transpiration rate of leaf decreased grad- ually, while water use efficiency increased significantly from 3.53 to 9.23 μmol CO2 per mol H20 with the decrease of soil water potential from --20 to --80 kPa. The height, canopy width, tiller number, shoot dry weight and root dry weight of C. leucochlora decreased significantly for all treatments with the de- crease of soil water potential compared to control. But plants grew normally and kept good landscape effect under all irrigation treatments. It is concluded that C. leucochlora should be irrigated when soil water po- tential declined to --80 kPa for water-saving irrigation during the flowering and fruiting period. It saved 32.3% water than irrigated under --20 kPa soil water potential.