干旱区枸杞树干液流变化特征及其影响因素

树干液流作为植物蒸散作用的水分来源,是植物水分消耗的直观量化监测指标,利用包裹式树干液流监测技术获取干旱区枸杞全生育期树干液流实时数据,分析了不同时间尺度树干液流变化特征及各气象要素对树干液流的影响,为明晰枸杞耗水规律及其影响因素提供了重要的佐证。结果表明:枸杞的树干液流量昼夜差异较大,白天液流量是夜间的10倍左右;晴天液流速率、日累积量及变化幅度均大于阴雨天气,晴天液流速率变化曲线且呈宽峰型,在06:30左右启动较阴天提前30min;夏季树干液流启动时间为6:00比秋季提前1h左右,夏季的峰值123g/h。盛果期液流速率最大10.32g/h,营养生长期最小1.35 g/h;6—8月旺盛生长季,平均日耗水1388.3g/d,5—11月全生育期日均耗水1102.7g/d;树干液流速率与太阳辐射、空气温度均呈极显著正相关关系,与相对湿度呈负相关关系;枸杞树干液流(F)与太阳辐射(S)、温度(T)、相对湿度(H)及饱和水汽压(VPD)符合方程F=41.5+0.167S-0.563H+1.36T-9.67VPD(R~2=0.6547)。

Analysis of variation in and factors influencing sap flow in stems of Lycium barbarum in an arid area

Sap flow is the source of water for plant evapotranspiration, which is the direct quantitative index of plant water consumption. We monitored the sap flow of Lycium barbarum continuously with stem heat and balance sap flow monitoring techniques for the entire growing season in an arid region of Ningxia. We used these data to analyze the variation in sap flow and determine its relationship with meteorological factors on different time scales. Our goal was to provide evidence to clarify the amount of water consumption by Lycium barbarum and the factors that influenced water consumption. The results indicated the occurrence of diurnal variation in sap flow. Sap flow was approximately 10 times greater during the day than at night. Sap flow started around 06:30 and occurred approximately 30 min earlier on cloudy days. Additionally, the sap flow rate curve had a broad peak on sunny days. In summer, sap flow started at 06:00, 1 hour earlier than in autumn, and the maximum sap flow rate was 123 g/h. The sap flow rate was greatest during the full fruiting period and had a minimum value during the vegetative period. It increased rapidly from June to August when water consumption was 1388.3 g/d. Average daily water consumption was 1102.7 g/d during the entire growth period. We also found that the sap flow rate was positively correlated with solar radiation and air temperature, whereas a negative correlation with relative humidity was detected. Furthermore, sap flow (F) expresses the following quantitative relationship with solar radiation (S), temperature (T), relative humidity (H), and vapor pressure differential (VPD):F=41.5+0.167S-0.563H+1.36T-9.67VPD (R²=0.6547).