Large Variations in the Transpiration of Sorghum Canopies Under High Evaporative Demand Are Positively Related to Water Use Efficiency

Pilloni, R and Aparna, K and Ghazzal, Z E and Kar, S and Hajjarpoor, A and Xue, W and Affortit, P and Ribière, W and Badji, R and Sine, B and Kholova, J and Tardieu, F and Vadez, V (2025) Large Variations in the Transpiration of Sorghum Canopies Under High Evaporative Demand Are Positively Related to Water Use Efficiency. Plant, Cell & Environment (TSI), 49 (3). pp. 1544-1560. ISSN 0140-7791

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Abstract

Transpiration restriction under high vapour pressure deficit (VPD), measured indoors with individual plants, increases water use efficiency (WUE). However, VPD is not the only factor driving transpiration, individual plants in a field rapidly become a canopy, and reports on the transpiration restriction versus WUE are scant. We analyzed the transpiration response to the evaporative demand (Penman-Monteith reference evapotranspiration, ETref) and WUE in sorghum canopies outdoors. These responses showed no plateau at high ETref in 47 genotypes. The slope of the resulting linear relationship over the whole range of ETref showed a large genetic variability. Unexpectedly, this slope was positively correlated with WUE in experiments with high ETref. Conversely, a (classical) negative correlation was observed under low ETref. Genotypes with high WUE and response to ETref allowed maximum light penetration into the canopy, via more erect leaf orientation. VPD in the canopy was also lower than in open air when the leaf area index reached 2.5-3. We interpret that higher WUE related to a larger proportion of plant photosynthesis being contributed by lower level leaves that received light and faced lower VPD than leaves exposed to air VPD. This study opens new opportunities, agronomic and genetic, to improve WUE.

Item Type:	Article
Divisions:	Global Research Program - Accelerated Crop Improvement
CRP:	UNSPECIFIED
Uncontrolled Keywords:	climate change, drought, light interception, lysimeter, sowing density, transpiration restriction, vapour pressure deficit
Subjects:	Others > Crop Physiology Mandate crops > Sorghum Others > Drought Others > Climate Change
Depositing User:	Mr Nagaraju T
Date Deposited:	31 Mar 2026 03:55
Last Modified:	31 Mar 2026 03:55
URI:	http://oar.icrisat.org/id/eprint/13577
Official URL:	https://onlinelibrary.wiley.com/doi/epdf/10.1111/p...
Projects:	UNSPECIFIED
Funders:	UNSPECIFIED
Acknowledgement:	The senior and corresponding authors are in part supported by a grant the Make Our Planet Great Again (MOPGA) ICARUS project (Improve Crops in Arid Regions and Future Climates) funded by the French Agence Nationale de la Recherche and by the Region Occitanie (ANR, grant ANR-17-MPGA-0011).
Links:	Google Scholar

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