吐鲁番盆地杏树树干液流变化特征及其对环境因子的响应

Sap flow characteristics of Prunus armeniaca L.and its response to environmental factors in Turpan Basin

利用PS-TDP8插针式热扩散探针技术,在不同生长季节对吐鲁番盆地杏树树干液流变化进行监测,并同步记录果园气象因子,分析杏树树干液流变化规律,建立树干液流与环境因子之间的关系模型,为干旱地区杏高效、节水栽培提供依据。结果表明:吐鲁番盆地杏树树干液流速率日变化具有明显的昼夜变化规律,6、7月液流速率日变化峰值为最大,分别达到0.71、0.78 g·s^(-1);杏液流速率表现为晴天高于阴天,且晴天液流产生时间比阴天早1 h;夏季液流启动时间于07:30—08:00左右,比春季和秋季早1 h,并持续时间长,单位时间内的液流量大,这导致夏天杏树液流速率峰值最大,平均单位时间液流量、日平均液流量及月液流量均高于其他季节,分别为0.461 L·h^(-1)、11.062 L·d^(-1)、331.68 L·month^(-1)。气温、光照辐射和水汽压亏缺的变化规律与液流速率的变化规律基本上一致,呈现出极显著正相关关系(P<0.01);相对湿度的变化规律与杏树树干液流速率日变化规律相反,呈现出极显著负相关关系(P<0.01)。构建了杏树树干液流速率与环境因子的逐步回归模型,各方程均达到极显著水平,各月份决定系数R2均大于0.85以上,拟合良好。总之,吐鲁番盆地夏日光照辐射强,气温较高,夏季杏树液流量加快,蒸腾耗水量增加,因此夏季要及时灌溉,且灌溉时间宜选日出前或日落后,避免蒸发造成灌溉水损失。

We measured the sap flow of Prunus armeniaca L.in Turpan Basin,using the PSTDP8 pin-type thermal diffusion probe technology,and recorded the meteorological factors of the orchard synchronously,with the aim to establish the relationship between sap flow and environmental factors.Results from this study can provide a basis for efficient and water-saving cultivation of P.armeniaca in arid areas.The results showed that sap flow rate of P.armeniaca showed obvious diurnal variation.The peak value of sap flow rate occurred in June and July,being 0.71 and 0.78 g·s^(-1),respectively.The sap flow rate was higher on a sunny day than on a cloudy day,and the start-up time of sap flow on a sunny day was 1 h earlier than that on a cloudy day.The starting time of sap flow in summer was around 07:30-08:00,which was 1 h earlier than that of spring and autumn,with a long duration and large flow amount per unit time.Such changes caused the average unit time sap flow,daily average sap flow,and monthly sap flow of P.armeniaca being the largest in summer,which were 0.461 L·h^(-1),11.062 L·d^(-1),and 331.68 L·month-1,respectively.The variations of air temperature,solar radiation,and water pressure deficit were basically consistent with the variations of sap flow rate,with a significant positive correlation between them(P<0.01).The variations of relative humidity were negatively correlated with the diurnal variations of sap flow rate(P<0.01).Stepwise regression models between stem sap flow rate and environmental factors were established.The model well fit the relationship between sap flow rate of P.armeniaca and environmental factors,with the coefficient of determination(R2)in each month was larger than 0.85 in the regression model.To sum up,the sap flow rate of P.armeniaca was quickened and transpirational water consumption was increased by strong solar radiation and high temperature in summer.Therefore,we should increase the irrigation frequency in summer days.The irrigation time should be selected before sunrise or after sunset to reduce water loss due to evaporation.