Analyses on water use characteristics of Salix psammophila based on sap flow and leaf water potential
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摘要:目的 干旱半干旱区植物的水分传输过程依赖于一套有效的调控机制，研究典型沙生植物对土壤干旱的响应机制有助于预测未来气候条件下荒漠生态系统的结构和功能变化。方法 采用包裹式茎流仪于2017年5—10月对毛乌素沙地沙柳液流进行长期连续观测，期间选择天气晴朗的19 d测得黎明前叶水势与正午叶水势，同步连续监测林冠上方太阳辐射、气温、空气相对湿度与土壤含水量。结果 （1）短期内土壤水势与枝条液流具有较好的相关性（5—6月、7—9月），整个生长季内液流密度与土壤叶片水势差（ΨL－ΨS）呈正相关。（2）叶片水势（ΨL）、大气水汽压亏缺（VPD）均对叶片蒸腾速率（EL）有调控作用，小于阈值呈正相关，大于阈值呈负相关。VPD对EL调控阈值为1.9 kPa，ΨL对EL调控阈值为−3.7 MPa。VPD对叶片导度（gL）有显著调控作用，调控阈值为0.9 kPa，小于阈值呈正相关，大于阈值呈负相关。（3）沙柳木质部栓塞脆弱性曲线呈“r”形，引起枝条50%导水率损失的压力值（P50）为0.73 MPa。（4）整体上看，正午木质部传导度（Ks）与正午叶片传导度（gL）是正相关的。Ks与黎明前叶水势（ΨS）呈现正相关关系，而gL受VPD影响较大导致其与ΨS相关性弱。gL与Ks对于土壤干旱（ΨS降低）的相对敏感性（ϭ）为 1.035 。结论 以上结果表明，随着水分胁迫加重，木质部在水势较高时便通过降低导水率来减少水分丧失，木质部栓塞到一定程度也不关闭气孔，而是能保持一定的气孔开度。这些适应策略在一定程度上反映了沙柳最大化蒸腾和同化速率的一种机制，对正确认识干旱地区沙柳的水分利用特征有明显的理论意义，为深入研究沙柳的水力限制补偿机理奠定基础。Abstract:Objective In arid and semi-arid areas, water transfer process of plants is regulated by a set of effective mechanisms. Understanding the mechanisms of responses of xerophytic plants to soil drought is important for predicting the structure and functioning of dryland ecosystems under changing climate.Method The stem sap flow of Salix psammophila was monitored continuously using five heat balance sensor, and the leaf water potential of the plant was measured at predawn and midday in nineteen sunny days during 1 May to 10 October, 2017. The photosynthetic active radiation above canopy, air temperature, air relative humidity, and soil moisture content were monitored simultaneously.Result The results were that the sap flux density and soil water potential were highly correlated in short term (May to June, July to September). The sap flux density and the water potential drop (ΨL−ΨS) were positively correlated during the growing season. Leaf transpiration rate increased with leaf water potential and vapor pressure deficit (VPD), respectively, saturating at −3.7 MPa and 1.9 kPa, leaf conductance for water vapour increased positively with VPD, saturating at 0.9 kPa, then decreasing with these variables when greater than their respective threshold. The vulnerability curve was “r” shape for Salix psammophila. The water potential, at which 50% of hydraulic conductivity was lost as a result of xylem embolism (P50), was 0.72 MPa. The whole-branch hydraulic conductance per unit basal sapwood cross-sectional area (Ks) increased with soil water potential (ΨS) and leaf conductance (gL). The correlation between gL and ΨS was low because of the influence of VPD on gL. The relative sensitivity of stomata and plant hydraulic conductance to declining soil water potentials (ϭ) was 1.035.Conclusion The results show that as water stress develops, Salix psammophila controls the water loss by reducing the Ks and certain level of xylem embolism does not induce the closure of the stomata. This mechanisms may be advantageous in terms of maximizing transpiration and assimilation rates. It has obvious theoretical significance to understand the water use characteristics of plants in arid areas, and lays a foundation for further study on the mechanism of the compensation for hydraulic limitation of Salix psammophila.
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Key words:
- sap flow /
- transpiration /
- leaf potential /
- hydraulic conductance /
- leaf conductance for water vapour
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图 1 枝条液流与土壤−叶片水势的动态变化
Figure 1. Dynamic changes of plant sap flow and soil-leaf water potential
图 2 正午叶片蒸腾与叶片水势、大气水汽压亏损的关系
空心圆表示饱和水汽压差大于2.7 kPa的点。Hollow points are the point which VPD is greater than 2.7 kPa.
Figure 2. Relationship between leaf transpiration and leaf water potential, vapour pressure deficit
图 5 沙柳黎明前叶水势与正午叶水势的关系
Figure 5. Relationship between predawn and midday leaf water potential of Salix psammophila
表 1 被测沙柳样株的基本特征及茎流传感器型号
Table 1. Basic properties of the measured samples of Salix psammophila and sap flow sensor type
编号
No.传感器型号
Sensor type茎干直径 Stem diameter/mm 株高 Stem length/m 冠幅 Crown width/m × m 1 SGA13 12.26 2.5 2.5 × 1.8 2 SGA13 13.02 2.6 3.0 × 2.1 3 SGA9 9.12 1.9 2.0 × 1.7 4 SGA9 9.54 2.1 2.3 × 2.0 5 SGA9 9.38 2.4 2.1 × 1.9 
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[1] Sperry J S, Hacke U G, Oren R, et al. Water deficits and hydraulic limits to leaf water supply[J]. Plant, Cell & Environment, 2002, 25(2): 251−263. [2] Tyree M T, Sperry J S. Do woody plants operate near the point of catastrophic xylem dysfunction caused by dynamic water stress? Answers from a model[J]. Plant Physiology, 1988, 88(3): 574−580. doi: 10.1104/pp.88.3.574 [3] Zimmermann M H. Xylem structure and the ascent of sap[J]. Science, 2002, 222: 500−501. [4] Sperry J S, Tyree M T. Water-stress-induced xylem embolism in three species of conifers[J]. Plant Cell & Environment, 1990, 13(5): 427−436. [5] 孙谷畴, 赵平, 曾小平, 等. 亚热带森林演替树种叶片气孔导度对环境水分的水力响应[J]. 生态学报, 2009, 29(2):698−705. doi: 10.3321/j.issn:1000-0933.2009.02.018Sun G C, Zhao P, Zeng X P, et al. Hydraulic responses of stomatal conductance in leaves of successional tree species in subtropical forest to environmental moisture[J]. Acta Ecologica Sinica, 2009, 29(2): 698−705. doi: 10.3321/j.issn:1000-0933.2009.02.018 [6] Comstock J, Mencuccini M. Control of stomatal conductance by leaf water potential in Hymenoclea salsola (T. & G.), a desert subshrub[J]. Plant Cell & Environment, 2010, 21(10): 1029−1038. [7] Oren R, Sperry J S, Katul G G, et al. Survey and synthesis of intra- and interspecific variation in stomatal sensitivity to vapour pressure deficit[J]. Plant, Cell & Environment, 2010, 22(12): 1515−1526. [8] Stocker O. Die abhängigkeit der transpiration von den umweltfaktoren[M]// Pflanze und wasser/ water relations of plants. Berlin: Springer, 1956. [9] Jones H G. Stomatal control of photosynthesis and transpiration[M]// Illustrated guide to surgical practice. Churchill: Livingstone, 1998: 387−398. [10] Tardieu F, Simonneau T. Variability among species of stomatal control under fluctuating soil water status and evaporative demand: modelling isohydric and anisohydric behaviours[J]. Journal of Experimental Botany, 1998, 49(2): 419−432. [11] McDowell N G, Pockman W T, Allen C D, et al. Mechanisms of plant survival and mortality during drought: why do some plants survive while others succumb to drought?[J]. New Phytologist, 2008, 178: 719−739. doi: 10.1111/j.1469-8137.2008.02436.x [12] Domec J C, Johnson D M. Does homeostasis or disturbance of homeostasis in minimum leaf water potential explain the isohydric versus anisohydric behavior of Vitis vinifera L. cultivars?[J]. Tree Physiology, 2012, 32(3): 245. doi: 10.1093/treephys/tps013 [13] Martínez-Vilalta J, Poyatos R, Aguadé D, et al. A new look at water transport regulation in plants[J]. New Phytologist, 2015, 204(1): 105−115. [14] Campbell G S, Norman J M. An introduction to environmental biophysics[J]. Biologia Plantarum, 1979, 21(2): 104−104. doi: 10.1007/BF02909456 [15] 李吉跃, 翟洪波. 木本植物水力结构与抗旱性[J]. 应用生态学报, 2000, 11(2):301−305. doi: 10.3321/j.issn:1001-9332.2000.02.037Li J Y, Zhai H B. Hydraulic architecture and drought resistance of woody plants[J]. Chinese Journal of Applied Ecology, 2000, 11(2): 301−305. doi: 10.3321/j.issn:1001-9332.2000.02.037 [16] Michael G R, Barbara J Y. Hydraulic limits to tree height and tree growth[J]. Bioscience, 1997, 47(4): 235−242. doi: 10.2307/1313077 [17] Hubbard R M, Bond B J, Ryan M G. Evidence that hydraulic conductance limits photosynthesis in old Pinus ponderosa trees[J]. Tree Physiology, 1999, 19: 165−172. doi: 10.1093/treephys/19.3.165 [18] Tyree M T , Sperry J S. Vulnerability of xylem to cavitation and embolism[J]. Annual Review of Plant Physiology & Plant Molecular Biology, 1989, 40(40): 19−38. [19] 翟洪波, 李吉跃,李保华, 等. Darcy定律在测定油松木质部导特征中的应用[J]. 北京林业大学学报, 2001, 23(4):6−9. doi: 10.3321/j.issn:1000-1522.2001.04.002Zhai H B, Li J Y, Li B H, et al. Application of Darcy's laws in testing water conductivity characteristics of Pinus tabulaeformis xylem[J]. Journal of Beijing Forestry University, 2001, 23(4): 6−9. doi: 10.3321/j.issn:1000-1522.2001.04.002 [20] Saliendra N Z, Sperry J S, Comstock J P. Influence of leaf water status on stomatal response to humidity, hydraulic conductance, and soil drought in Betula occidentalis[J]. Planta, 1995, 196(2): 357−366. [21] 王珊, 查天山, 贾昕, 等. 毛乌素沙地油蒿群落冠层导度及影响因素[J]. 北京林业大学学报, 2017, 39(3):65−73.Wang S, Zha T S, Jia X, et al. Temporal variation and controlling factors of canopy conductance in Artemisia ordosica community[J]. Journal of Beijing Forestry University, 2017, 39(3): 65−73. [22] 安锋, 张硕新. 7种木本植物根和小枝木质部栓塞的脆弱性[J]. 生态学报, 2005, 25(8):1928−1933. doi: 10.3321/j.issn:1000-0933.2005.08.014An F, Zhang S X. Studies of roots and shoots vulnerability to xylem embolism in seven woody plants[J]. Acta Ecologica Sinica, 2005, 25(8): 1928−1933. doi: 10.3321/j.issn:1000-0933.2005.08.014 [23] Mencuccini M. The ecological significance of long-distance water transport: short-term regulation, long-term acclimation and the hydraulic costs of stature across plant life forms[J]. Plant Cell & Environment, 2003, 26(1): 163−182. [24] Meinzer F C. Co-ordination of vapour and liquid phase water transport properties in plants[J]. Plant Cell & Environment, 2002, 25(2): 265−274. [25] Brodribb T J, Holbrook N M, Edwards E J, et al. Relations between stomatal closure, leaf turgor and xylem vulnerability in eight tropical dry forest trees[J]. Plant Cell & Environment, 2003, 26(3): 443−450. [26] Willigen C V D, Pammenter N W. Relationship between growth and xylem hydraulic characteristics of clones of Eucalyptus spp. at contrasting sites[J]. Tree Physiology, 1998, 18(8−9): 595. [27] Granier A, Loustau D, Bréda N. A generic model of forest canopy conductance dependent on climate, soil water availability and leaf area index[J]. Annals of Forest Science, 2000, 57(8): 755−765. doi: 10.1051/forest:2000158 [28] Lu P, Biron P, Granier A, et al. Water relations of adult Norway spruce (Picea abies (L.) Karst) under soil drought in the Vosges mountains: whole-tree hydraulic conductance, xylem embolism and water loss regulation[J]. Annales Des Sciences Forestieres, 1996, 53(1): 113−121. doi: 10.1051/forest:19960108 [29] Irvine J, Perks M P, Magnani F, et al. The response ofPinus sylvestris to drought: stomatal control of transpiration and hydraulic conductance[J]. Tree Physiology, 1998, 18(6): 393−402. doi: 10.1093/treephys/18.6.393 [30] McDowell N G. Mechanisms linking drought, hydraulics, carbon etabolism, and vegetation mortality[J]. Plant Physiology, 2011, 155: 1051−1059. doi: 10.2307/41434180 -
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