半干旱地区草坪草和主要杂草水势的日变化特征分析

An Analysis of Diurnal Changes of WaterPotential of Lawn Grass and Weeds in Semiarid Zone

分析了半干旱地区草坪草和几种主要杂草的水势的日变化特征及其差异性,发现不同植物水势的日变化趋势都为单峰曲线,早晨5:00水势最高,在15:00达到最低值.草坪草草地早熟禾的水势在四种植物中为最高或较高,天蓝苜蓿的水势一直为最低.在土壤水饱和的情况下,四种植物水势的日变化与五层土壤含水量都无显著相关关系.草地早熟禾、早开堇菜、天蓝苜蓿水势的日变化都与冠层温度有相关关系,与其它环境因素无显著相关关系,而止血马唐水势的日变化与四种环境因素都无显著相关关系.

Diurnal changes of water potential of a kind of lawn grass (Poa Pratensis L.) and some main weeds (Medicago lupulina L.,Viola prionantha Bunge,Digitaria ischaemum (Schred.) Schreb.ex Muhl) in semiarid zone were analysed.Some characteristics and differences of them were obtained.Curves of diurnal changes of water potential of different plants all tended to be 'single peak' type.The water potential was highest at five o′clock in the morning and lowest at fifteen o′clock in the afternoon.Among the four plants,water potential of the lawn grass (Poa Pratensis L.) was usually the highest and that of Medicago lupulina L.was always the lowest.Under the condition of saturated soil moisture,there was no remarkable correlation between diurnal changes of water potential of four plants and water content in five layers of soil.The diurnal changes of water potential of Poa Pratensis L.,Viola prionantha Bunge,Medicago lupulina L.were respectively related to conopy temperature,but the correlation between diurnal changes of water potential and other environmental factors was not remarkable.The diurnal changes of water potential of Digitaria ischaemum (Schred.) Schreb.ex Muhl and four environmental factors had no remarkable correlation.