不同水分条件下宁夏枸杞氢氧稳定同位素变化特征试验研究

Experiment on variation characteristics of hydrogen and oxygen stable isotopes of Lycium barbarum in Ningxia under different irrigation conditions

以宁夏枸杞为研究对象,采取试验区降水、不同灌溉量下枸杞根区土壤水、根系及茎秆样品并测定其氢氧稳定性同位素比率δ18 O和δD,分析不同降水量及灌溉量下枸杞稳定同位素的变化特征,利用IsoSource模型计算了枸杞对各潜在水源的可能利用比例.结果表明:试验区降水中δD和δ18 O之间有很好的线性关系,并得出了当地大气降水线的回归方程;不同灌溉量,枸杞主根系层(20~60 cm)的土壤含水率和与其对应的δD呈负相关趋势变化,随着土层深度加深,δD减小;降水量不同时,各土层δD变化规律相似,5 mm以下20 cm处的δD最大(-64.39‰),枸杞主要利用表层(0~20 cm)及部分中层(20~40 cm)的土壤水,分别占35.2%及25.1%;降水量为13.9 mm时,20~60 cm处δD相对较丰,为-65.20‰以上,枸杞可利用0~60 cm土层土壤含水量:0~20,20~40,40~60 cm土层的土壤水利用量分别占比22.4%,25.3%及23.2%.结论可为干旱区枸杞科学灌溉提供有益借鉴.

Considering the Lycium barbarum in Ningxia as research object,the rainfall data,root system and stem sample of the Lycium barbarum under different irrigation quotas and precipitations in the experiment filed were collected,then theδ18 O andδD values were measured to analyze the variation characteristics of stable isotope in the Lycium barbarum.The IsoSource model was used to calculate soil water utilization efficiency of each potential water sources to the Lycium barbarum.The results show that there is a good linear relationship betweenδD andδ18 O in precipitation and a line regression equation is built for the meteoric water line in the experimental field.The soil moisture content has a negative correlation with the correspondingδD of the Lycium barbarum under different irrigation quotas(20-60 cm),and theδD value decreases with deepening soil layer.The variation pattern ofδD in different soil layers is similar to that in 20 cm below 5 mm precipitation,where the maximumδD value is-64.39‰.The Lycium barbarum mainly utilizes the water in the surface soil layer(0-20 cm)and middle soil layer(20-40 cm)respectively with utilization efficiencies of 35.2%and 25.1%.The value ofδD in 20-60 cm is richer(>-65.20‰)when the precipitation is 13.9 mm.The Lycium barbarum can make use of soil water content in 0-60 cm deep soil layer,especially the water utilization efficiencies in 1-20,20-40 and 40-60 cm layers are 22.4%,25.3%and 23.2%,respectively.The conclusion can provide a reference for reasonable irrigation of Lycium barbarum in arid regions.