渗透胁迫条件下植物茎叶水势的变化——以塔里木河下游胡杨为例

Response of Leaf and Stem Water Potential of Populus Euphratica to Osmotic Stress in Lower Reaches of Tarim River

通过对塔里木河下游英苏断面和阿拉干断面2003年和2004年胡杨(Populus euphratica)叶、茎水势测定结果分析表明,大部分位点的胡杨茎水势都低于叶水势,而且相差幅度也比较大,说明塔里木河下游河道附近的胡杨目前仍然处于比较严重的水分胁迫条件下;该地区胡杨叶、茎水势呈现出的与其他植物水势日变化规律不同的早晚低、中午高的反梯度现象,说明在塔里木河下游影响胡杨水势的多重因素中,气温不是主导因素;运用SAS6.12软件对胡杨叶、茎水势和地下水位、土壤盐分进行相关分析,结果表明其相关系数均未达到显著水平。2003年和2004年英苏断面和阿拉干断面胡杨叶、茎水势回归方程分别为:英苏叶水势=42.49-4.47(地下水位)-16.94(土壤盐分),离回归标准差为16.07082,决定系数R2=0.4946;阿拉干叶水势=-17.38-1.04(地下水位)+1.00(土壤盐分),离回归标准差为3.91396,决定系数R2=0.3778;英苏茎水势=-59.13+2.93(地下水位)+3.87(土壤盐分),离回归标准差为8.67742,决定系数R2=0.2487;阿拉干茎水势=-34.72-0.40(地下水位)+2.21(土壤盐分),离回归标准差为4.3210,决定系数R2=0.5952,回归分析结果显示两断面两年内的叶、茎水势依地下水位和土壤盐分的二元线性回归方程未显著存在,偏回归系数的检验也未达显著水平,表明塔里木河下游胡杨叶、茎水势对地下水位和土壤盐分的响应不强烈,并由此分析推断出土壤含水量对胡杨水势的影响大于地下水位对其影响,这为目前一些专家建议的由“线形”输水方式逐步转向“河道输水与面上供水相结合的方式”提供了理论依据。

The measurement results of water potential of Populus Euphratica in lower＂ reaches of Tarim River in 2003 and 2004 showed that stem water potential in most plots was lower than leaf water potential and there was a great difference between them, which indicated that Populus Euphratica near lower reaches of Tarim River was still under the condition of more serious water stress. The antigradient phenomenon presented by stem and leaf water potential of Populus Euphratica in this area which was different from the daily variation of other plants explained that the temperature was not a predominant factor in a variety of factors influencing the water potential of Populus Euphratica in lower reaches： of Tarim River. The relattion analysis between stem/leaf water potential and groundwater level/soil salt, making use of the SAS6.12 software, illuminated that both regression equations and partial regression coefficients in two years felt short of significance level, which revealed that the stem and leaf water potential of Popubzs Euphratica in lower reaches of Tarim River responded to groundwater level and soil salt less seriously. It could be inferred that soil water content had a greater effect upon the water potential of Populus Euphratica than that of groundwater level, which provided theoretical basis for the suggestion put forward by some experts currently： to turn ＂alignment＂ water inputting method to ＂combining water inputting and water supplying＂ method gradually.