形态变化对叶片表面温度的影响

doi:10.17521/cjpe.2017.0127

摘要/Abstract

摘要：

干旱区植物叶片形态可塑性是植物适应高温干旱环境的重要生存策略, 但目前仍缺乏直观的数据予以证明。该研究应用热成像技术和图像分析技术, 同步测定真实叶片与模拟叶片的叶温、形态及风速、辐射和温度等环境参数。研究结果显示: 在干旱、高温环境下, 除了蒸腾, 叶片形态变化也是调控叶温的重要因子。干旱区植物叶片变小, 有利于加速叶片与环境的物质及热量交换, 从而达到降低叶温的目的。样地数据显示, 在高温、低风速环境下, 叶片宽度每减少1 cm, 叶片表面温度降低约2.1 ℃, 而模拟叶片叶宽度每减少1 cm, 叶片表面温度降低0.60-0.86 ℃。该研究对深入理解植物生存策略与环境适能力具有重要意义。

关键词: 叶片形态, 叶片温度, 热成像, 叶片边界层阻力

Abstract:

Aims The shape plasticity of plant leaves is an important survival strategy to high temperature and drought in arid region, yet reliable evidences are insufficient to validate the fundamental concepts. Our objective was to demonstrate the specific effects of leaf morphology on leaf surface temperature.

Methods Infrared thermal images were processed to determine the leaf temperature and shape parameters of simulated and actual leaf shape. Microclimatic conditions were recorded using a automatic weather station near the sampling plot, including wind speed, radiation and air temperature.

Important findings Under the drought and high temperature, the plasticity of leaf shape appeared an important measure to regulate leaf temperature, except leaf transpiration. The exchange rates of matter and energy between leaves and the environment were enhanced by smaller leaves that effectively decreased leaf temperature. With low wind speed and high temperature, leaf surface temperature decreased 2.1 °C per 1 cm reduction in leaf width. However, leaf surface temperature of a simulated leaf decreased 0.60-0.86 °C per 1 cm reduction in leaf width. Results from this study will help us to understand plant adaptability and survival strategy in arid region.

Key words: leaf shape, leaf temperature, infrared thermal imaging, leaf boundary layer resistance

李永华, 李臻, 辛智鸣, 刘明虎, 李艳丽, 郝玉光. 形态变化对叶片表面温度的影响. 植物生态学报, 2018, 42(2): 202-208. DOI: 10.17521/cjpe.2017.0127

LI Yong-Hua, LI Zhen, XIN Zhi-Ming, LIU Ming-Hu, LI Yan-Li, HAO Yu-Guang. Effects of leaf shape plasticity on leaf surface temperature. Chinese Journal of Plant Ecology, 2018, 42(2): 202-208. DOI: 10.17521/cjpe.2017.0127

导出引用管理器 EndNote|Ris|BibTeX

链接本文: https://www.plant-ecology.com/CN/10.17521/cjpe.2017.0127

https://www.plant-ecology.com/CN/Y2018/V42/I2/202

图/表 7

表1 叶片形态参数间的相关分析

Table 1 Correlation coefficient among different measures of leaf shape

	周长 Perimeter	面积 Area	长度 Length	最大宽度 Maximum width
周长 Perimeter	1.00
面积 Area	0.79^*	1.00
长度 Length	0.82^**	0.91^**	1.00
最大宽度 Maximum width	0.94^**	0.89^**	0.79^*	1.00

图1 A, 风洞中测试模拟叶片的表面温度。B, 模拟叶片形态。C, 模拟叶片的热成像图片。

Fig. 1 A, Surface temperature measurement of simulated leaf in a wind tunnel. B, Leaf shape of simulated leaf. C, A thermal image of a simulated leaf.

图2 蒸腾、叶宽对叶片温度的影响(平均值±标准误差)。

Fig. 2 Empirical relationships between maximal leaf width, leaf transpiration rate and leaf temperature (mean ± SE).

图3 不同风速下叶宽对模拟叶片温度的影响。

Fig. 3 Empirical relationships between maximal leaf width and leaf temperature in a wind tunnel under different air flow velocity.

图4 风速、辐射、气温对叶片温度的影响(平均值±标准误差)。

Fig. 4 Empirical relationships among wind speed, radiation, air temperature and leaf temperature (mean ± SE).

图5 风速、辐射、气温对模拟叶片温度的影响。

Fig. 5 Empirical relationships among wind speed, radiation, air temperature and leaf temperature.

图6 单叶表面温度分布特征。A, 模拟叶片, 面积1.80 cm2, 气温32.3 ℃, 辐射478.6 W·m-2, 风速< 0.3 m·s-1。B, 模拟叶片, 面积23.7 cm2, 气温31.9 ℃, 辐射483.1 W· m-2, 风速< 0.3 m·s-1。C, 真实叶片, 面积5.4 cm2, 气温33.8 ℃, 辐射1β152.9 W·m-2, 风速0.7 m·s-1, 蒸腾1.9 mmol· m-2·s-1。A1、B1、C1是叶片热图像。A2、B2、C2是叶片表面温度分布特征。A3、B3、C3是叶片表面温度剖面线。HD, 距离下风向叶片边缘的水平距离; R, 不同叶片温度的分布区面积占叶片总面积的比例。L1-L5, 叶片上的位置。

Fig. 6 Spatial changes in leaf temperature. A, Simulated leaf, leaf area 1.80 cm2, air temperature 32.3 °C, solar radiation 478.6 W·m-2, wind speed < 0.3 m·s-1. B, Simulated leaf, leaf area 23.7 cm2, air temperature 31.9 °C, solar radiation 483.1 W·m-2, wind speed < 0.3 m·s-1. C, Real leaf, leaf area 5.4 cm2, air temperature 33.8 °C, solar radiation 1β152.9 W·m-2, wind speed 0.7 m·s-1, transpiration rate 1.9 mmol·m-2·s-1. A1, B1, C1 were the thermal image of three leaf. A2, B2, C2 were temperature distributions on a leaf. A3, B3, C3 were temperature profile of a leaf. HD, horizontal distance from the leaf edge of the downwind direction; R, ratio of the distribution area of different leaf temperatures to the total leaf area. L1-L5, location on the leaves.

参考文献 29

[1]	Bragg J, Westoby M ( 2002). Leaf size and foraging for light in a sclerophyll woodland. Functional Ecology, 16, 633-639. DOI URL
[2]	Ehleringer J (1980). Leaf morphology and reflectance in relation to water and temperature stress. In: Turner NC, Kramer PC eds .Adaptation of Plants to Water and High Temperature Stress. Wiley-Interscience, New York. 295-308.
[3]	Geller G, Smith W ( 1982). Influence of leaf size, orientation, and arrangement on temperature and transpiration in three high-elevation, large-leafed herbs. Oecologia, 53, 227-234. DOI URL PMID
[4]	Heckathorn SA, DeLucia EH ( 1991). Effect of leaf rolling on gas exchange and leaf temperature of Andropogon gerardii and Spartina pectinata. Botanical Gazette, 152, 263-268.
[5]	Helliker BR, Richter SL ( 2008). Subtropical to boreal convergence of tree-leaf temperatures. Nature, 454, 511-514. DOI URL PMID
[6]	Jones HG ( 2005). Application of thermal imaging and infrared sensing in plant physiology and ecophysiology. Advances in Botanical Research, 41, 107-163. DOI URL
[7]	Juurola E, Aalto T, Thum T, Vesala T, Hari P ( 2005). Temperature dependence of leaf-level CO2 fixation: Revising biochemical coefficients through analysis of leaf three- dimensional structure. New Phytologist, 166, 205-215. DOI URL PMID
[8]	Konis E ( 1950). The effect of leaf temperature on transpiration. Ecology, 31, 147-148. DOI URL
[9]	Lambers H, Chapin III FS, Pons TL ( 1998). Plant Physiological Ecology. Springer-Verlag, New York.
[10]	Li YH, Lu Q, Wu B, Zhu YJ, Liu DJ, Zhang JX, Jin ZH ( 2012). A review of leaf morphology plasticity linked to plant response and adaptation characteristics in arid ecosystems. Chinese Journal of Plant Ecology, 36, 88-98. (in Chinese with English abstract) DOI URL
	[ 李永华, 卢琦, 吴波, 朱雅娟, 刘殿君, 张金鑫, 靳占虎 ( 2012). 干旱区叶片形态特征与植物响应和适应的关系. 植物生态学报, 36, 88-98.] DOI URL
[11]	Liu Y, Subhash C, Yan J, Song C, Zhao J, Li J ( 2011). Maize leaf temperature responses to drought: Thermal imaging and quantitative trait loci (QTL) mapping. Environmental and Experimental Botany, 71, 158-165. DOI URL
[12]	Liu MH, Xin ZM, Xu J, Sun F, Dou LJ, Li YH ( 2013). Influence of leaf size of plant on leaf ranspiration and temperature in arid regions. Chinese Journal of Plant Ecology, 37, 436-442. (in Chinese with English abstract) DOI URL
	[ 刘明虎, 辛智鸣, 徐军, 孙非, 窦立军, 李永华 ( 2013). 干旱区植物叶片大小对叶表面蒸腾及叶温的影响. 植物生态学报, 37, 436-442.] DOI URL
[13]	McDonald P, Fonseca C, Overton J, Westoby M ( 2003). Leaf-size divergence along rainfall and soil-nutrient gradients: Is the method of size reduction common among clades? Functional Ecology, 17, 50-57. DOI URL
[14]	Mebrahtu T, Hanover JW, Layne DR, Flore JA ( 1991). Leaf temperature effects on net photosynthesis, dark respiration, and photorespiration of seedlings of black locust families with contrasting growth rates. Canadian Journal of Forest Research, 21, 1616-1621. DOI URL
[15]	Nicotra A, Cosgrove M, Cowling A, Schlichting C, Jones C ( 2008). Leaf shape linked to photosynthetic rates and temperature optima in South African Pelargonium species. Oecologia, 154, 625-635. DOI URL PMID
[16]	Nobel P ( 2005). Physicochemical and Environmental Plant Physiology. 4th edn. Elsevier, Amsterdam, the Netherlands.
[17]	Parkhurst DF, Loucks O ( 1972). Optimal leaf size in relation to environment. Journal of Ecology, 60, 505-537. DOI URL
[18]	Roth-Nebelsick A ( 2001). Computer-based analysis of steady- state and transient heat transfer of small-sized leaves by free and mixed convection. Plant, Cell & Environment, 24, 631-640. DOI URL
[19]	Rouphael Y, Mouneimne AH, Ismail A, Mendoza-De Gyves E, Rivera CM, Colla G ( 2010). Modeling individual leaf area of rose (Rosa hybrida L.) based on leaf length and width measurement. Photosynthetica, 48, 9-15. DOI URL
[20]	Schuepp P ( 1993). Tansley review No. 59. Leaf boundary layers. New Phytologist, 125, 477-507. DOI URL
[21]	Smith W, Geller G ( 1980). Leaf and environmental parameters influencing transpiration: Theory and field measurements. Oecologia, 46, 308-313. DOI URL
[22]	Stokes VJ, Morecroft MD, Morison JIL ( 2006). Boundary layer conductance for contrasting leaf shapes in a deciduous broadleaved forest canopy. Agricultural and Forest Meteorology, 139, 40-54. DOI URL
[23]	Thuiller W, Lavorel S, Midgley G, Lavergne S, Rebelo T ( 2004). Relating plant traits and species distributions along bioclimatic gradients for 88 Leucadendron taxa. Ecology, 85, 1688-1699.
[24]	Vogel S ( 1968). “Sun leaves” and “shade leaves”: Differences in convective heat dissipation. Ecology, 49, 1203-1204. DOI URL
[25]	Vogel S ( 1970). Convective cooling at low airspeeds and the shapes of broad leaves. Journal of Experimental Botany, 21, 91-101. DOI URL
[26]	Vogel S ( 2009). Leaves in the lowest and highest winds: Temperature, force and shape. New Phytologist, 183, 13-26. DOI URL PMID
[27]	Westoby M, Falster DS, Moles AT, Vesk PA, Wright IJ ( 2002). Plant ecological strategies: Some leading dimensions of variation between species. Annual Review of Ecology and Systematics, 33, 125-159. DOI URL
[28]	Will RE, Wilson SM, Zou CB, Hennessey TC ( 2013). Increased vapor pressure deficit due to higher temperature leads to greater transpiration and faster mortality during drought for tree seedlings common to the forest-grassland ecotone. New Phytologist, 200, 366-374. DOI URL PMID
[29]	Wise RR, Olson AJ, Schrader SM, Sharkey TD ( 2004). Electron transport is the functional limitation of photosynthesis in field-grown Pima cotton plants at high temperature. Plant, Cell & Environment, 27, 717-724.