Effects of leaf shape plasticity on leaf surface temperature

doi:10.17521/cjpe.2017.0127

Abstract

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.

http://jtp.cnki.net/bilingual/detail/html/ZWSB201802007

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

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[J]. Chin J Plant Ecol, 2018, 42(2): 202-208.

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URL: https://www.plant-ecology.com/EN/10.17521/cjpe.2017.0127

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

Figures/Tables 7

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

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.

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

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

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

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

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.

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