Pearsall Kyle R, Williams Larry E, Castorani Sean, Bleby Tim M, McElrone Andrew J
Department of Viticulture and Enology, University of California - Davis, Davis, CA 95616, USA.
School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia.
Funct Plant Biol. 2014 Aug;41(8):874-883. doi: 10.1071/FP13156.
The aim of this study was to validate a novel, dual sap-flow sensor that combines two heat-pulse techniques in a single set of sensor probes to measure volumetric water use over the full range of sap flows found in grapevines. The heat ratio method (HRM), which works well at measuring low and reverse flows, was combined with the compensation heat-pulse method (CHPM) that captures moderate to high flows. Sap-flow measurements were performed on Vitis vinifera L. (cvv. Thompson seedless, Chardonnay and Cabernet Sauvignon) grapevines growing in a greenhouse and in three different vineyards, one of which contained a field weighing lysimeter. The combined heat-pulse techniques closely tracked diurnal grapevine water use determined through lysimetry in two growing seasons, and this was true even at very high flow rates (>6L vine-1h-1 for Thompson seedless vines in the weighing lysimeter). Measurements made with the HRM technique under low flow conditions were highly correlated (R2 ~ 0.90) with those calculated using the compensated average gradient method that is used to resolve low flow with the CHPM method. Volumetric water use determined with the dual heat-pulse sensors was highly correlated with hourly lysimeter water use in both years (R2=0.92 and 0.94 in 2008 and 2009 respectively), but the nature of the relationship was inconsistent among replicate sensors. Similar results were obtained when comparing grapevine water use determined from sap-flow sensors to miniaturised weighing lysimetry of 2-year-old potted vines and to meteorological estimates for field-grown vines in two additional vineyards. The robust nature of all of the correlations demonstrates that the dual heat-pulse sensors can be used to effectively track relative changes in plant water use, but variability of flow around stems makes it difficult to accurately convert to sap-flow volumes.
本研究的目的是验证一种新型双液流传感器，该传感器在一套传感探头中结合了两种热脉冲技术，以测量葡萄藤中发现的全范围液流的体积用水量。在测量低流量和反向流量方面表现良好的热比法（HRM）与用于捕获中高流量的补偿热脉冲法（CHPM）相结合。在温室和三个不同葡萄园（其中一个葡萄园装有田间称重蒸渗仪）中生长的酿酒葡萄（品种为汤普森无核、霞多丽和赤霞珠）上进行了液流测量。在两个生长季节中，组合热脉冲技术紧密跟踪了通过蒸渗仪测定的葡萄藤日用水量，即使在非常高的流量下（称重蒸渗仪中汤普森无核葡萄藤的流量>6L·藤⁻¹·h⁻¹）也是如此。在低流量条件下，用HRM技术进行的测量与使用补偿平均梯度法计算的测量高度相关（R²约为0.90），补偿平均梯度法用于用CHPM法解析低流量。在这两年中，用双热脉冲传感器测定的体积用水量与每小时蒸渗仪的用水量高度相关（2008年和2009年的R²分别为0.92和0.94），但重复传感器之间关系的性质不一致。当将液流传感器测定的葡萄藤用水量与两岁盆栽葡萄藤的小型称重蒸渗仪以及另外两个葡萄园田间生长葡萄藤的气象估计值进行比较时，也获得了类似的结果。所有相关性的稳健性质表明，双热脉冲传感器可用于有效跟踪植物用水量的相对变化，但茎周围流量的变异性使得难以准确转换为液流量。
