Tognetti R, Borghetti M
Istituto Miglioramento Genetico delle Piante Forestali, Consiglio Nazionale delle Ricerche, via A. Vannucci 13, 50134 Firenze, Italy.
Tree Physiol. 1994 Mar;14(3):241-50. doi: 10.1093/treephys/14.3.241.
We investigated the vulnerability of xylem to embolism and the seasonal occurrence of xylem embolism in Italian alder (Alnus cordata Loisel.) by acoustic and hydraulic methods. Wood anatomy was also studied. More than eighty percent of the vessels were less than 50 mm long and no vessels were longer than 120 mm. Mean vessel diameter was 48 micro m. Ultrasound acoustic emissions from root and branch segments dehydrating in air followed a similar pattern: in both tissues, emission peaks were recorded when the relative water content of the xylem was around 0.2. In branches dehydrating in air, xylem embolism increased linearly as water potential decreased. In trees in the field, more than 80 percent of hydraulic conductivity was lost in the tree crowns during winter. Recovery from winter embolism occurred mostly before bud burst. In summer, xylem embolism was low (< 30%) and acoustic emissions from roots, stem and branches of trees in the field were also low.
我们通过声学和水力方法研究了意大利桤木（Alnus cordata Loisel.）木质部栓塞的脆弱性以及木质部栓塞的季节性发生情况。还对木材解剖结构进行了研究。超过80%的导管长度小于50毫米，没有导管长度超过120毫米。平均导管直径为48微米。在空气中脱水的根和枝条段的超声声发射遵循相似模式：在两种组织中，当木质部相对含水量约为0.2时记录到发射峰值。在空气中脱水的枝条中，随着水势降低，木质部栓塞呈线性增加。在田间树木中，冬季树冠中超过80%的水力传导率丧失。冬季栓塞的恢复大多发生在芽萌发之前。在夏季，木质部栓塞率较低（<30%），田间树木的根、茎和枝条的声发射也较低。
