Abstract
Drought is considered to be one of the most devastating natural hazards, and it is predicted to become increasingly frequent and severe in the future. Understanding the plant gas exchange and water status response to drought is very important with regard to future climate change. We conducted a meta-analysis based on studies of plants worldwide and aimed to determine the changes in gas exchange and water status under different drought intensities (mild, moderate and severe), different photosynthetic pathways (C3 and C4) and growth forms (herbs, shrubs, trees and lianas). Our results were as follows: 1) drought negatively impacted gas exchange and water status, and stomatal conductance (gs) decreased more than other physiological traits and declined to the greatest extent in shrubs and C3 plants. Furthermore, C4 plants had an advantage compared to C3 plants under the same drought conditions. 2) The decrease in gs mainly reduced the transpiration rate (Tr), and gs could explain 55% of the decrease in the photosynthesis (A) and 74% of the decline in Tr. 3). Finally, gas exchange showed a close relationship with the leaf water status. Our study provides comprehensive information about the changes in plant gas exchange and water status under drought.
Highlights
Because the changes in A and Tr that result from changes in gs can themselves affect gs
When we divided the plant species into four growth forms, we found that herbs and shrubs showed the lowest and highest A, gs and Tr response ratios (Fig. 1a–c), respectively
When the two photosynthetic pathways were considered, we found that the response ratios of A, gs and Tr in C4 plants (− 0.619 ± 0.065, − 0.716 ± 0.067 and − 0.514 ± 0.069, respectively; P < 0.0001) were lower than those in C3 plants (− 0.777 ± 0.021, − 1.012 ± 0.028 and − 0.742 ± 0.028, respectively; P < 0.0001) (Fig. 1a–c), indicating that C4 plants performed better in the context of drought
Summary
Because the changes in A and Tr that result from changes in gs can themselves affect gs. Plant responses to drought and the relationship between gas exchange and water status, which depend on drought intensity, metabolic CO2 assimilation and biological form, are clearly complex[22]. To determine the central tendency and identify different patterns of plant response to drought, it is necessary to integrate results across studies. To this end, we conducted a meta-analysis based on global plant gas exchange and water status under drought and aimed to determine the changes in gas exchange (A, gs and Tr) and water status (leaf water potential and relative water content) of different types of plants and different drought intensities. Our results could improve the understanding of the response of plant gas exchange and water status to drought
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