The Responses of Plant Leaf CO2/H2O Exchange and Water Use Efficiency to Drought: A Meta-Analysis

Jinmeng Zhang,Jiaxin Jin,Xiuying Zhang,Hong Jiang,Xinzhang Song

doi:10.3390/su10020551

Jinmeng Zhang, Jiaxin Jin + Show 3 more

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https://doi.org/10.3390/su10020551

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Abstract

Persistent drought severely inhibits plant growth and productivity, which negatively affects terrestrial primary productivity worldwide. Therefore, it is important to investigate the impacts of drought on plant leaf CO2/H2O exchange and water use efficiency. This study assessed the responses of net photosynthesis (Pn), stomatal conductance (Gs), transpiration (Tr), and instantaneous water use efficiency (WUE) to drought based on a worldwide meta-analysis of 112 published studies. The results demonstrated that drought decreased Pn, Tr, and Gs significantly and differently among different moderators. C4 plants had smaller Pn reduction than C3 plants, which gives C4 plants an advantage in Pn. But their WUE decreased under drought conditions, indicating a great flexibility in C4 WUE. Annual herbs sacrificed WUE (−6.2%) to maintain efficient Pn. Perennial herbs took a different strategy in response to drought with an increased WUE (25.1%). Deciduous tree species displayed a greater increase in WUE than conifers and evergreen species. Additionally, Gs had a significant correlation with Pn and Tr, but an insignificant correlation with WUE, which could be because WUE is affected by other factors (e.g., air flow, CO2 concentration, and relative humidity). These findings have significant implications for understanding the worldwide effects of drought on plant leaf CO2/H2O exchange and water use efficiency.

Highlights

With a changing climate, drought has been predicted to be more intense and frequent in many regions of the world [1]
Drought intensity showed an adverse influence on plant leaf CO2/H2O exchange, with the most adverse effects appearing under severe stress
We found that drought strongly inhibited plant leaf CO2/H2O exchange (Figure 1), and the overall inhibitory effect increased with increasing drought stress

Summary

Introduction

Drought has been predicted to be more intense and frequent in many regions of the world [1]. Water scarcity has become one of the most adverse environmental factors for plant growth and productivity, limiting terrestrial primary productivity worldwide, especially in the semi-arid regions of the northern hemisphere [2,3]. As a primary resource for plant growth and productivity, water is directly or indirectly involved in all physiological processes. Plant leaf CO2/H2O exchange and water use efficiency (WUE, the ratio of net photosynthesis (Pn) to transpiration (Tr)) are important parameters for estimating vegetation productivity and for planning water use in arid and semi-arid areas. The effect of drought on leaf CO2/H2O exchange and WUE is a major issue, especially with a further changing climate [5,6,7]

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