RT Journal Article
SR Electronic
T1 Transpiration and water use efficiency of sorghum canopies have a large genetic variability and are positively related under naturally high evaporative demand
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2022.09.21.508841
DO 10.1101/2022.09.21.508841
A1 Raphaël Pilloni
A1 Kakkera Aparna
A1 Zineb El Ghazzal
A1 Soumyashree Kar
A1 A Ashok Kumar
A1 Amir Hajjarpoor
A1 Pablo Affortit
A1 William Ribière
A1 Jana Kholova
A1 François Tardieu
A1 Vincent Vadez
YR 2022
UL http://biorxiv.org/content/early/2022/09/22/2022.09.21.508841.abstract
AB Indoor experiments with individual plants often show that transpiration rate is restricted under high vapor pressure deficit (VPD), resulting in a plateau of transpiration that increases water use efficiency (WUE) of some genotypes. We tested this hypothesis outdoors during dry or rainy seasons of India and Senegal, based on the response of the transpiration of canopy-grown sorghum plants to the reference evapotranspiration that takes both light and VPD into account. This response showed no plateau at high evaporative demand in 47 genotypes, but a large genetic variability was observed for the slope of the relationship over the whole range of evaporative demand. Unexpectedly, this slope was genetically correlated with WUE in two experiments with high evaporative demand: genotypes that most transpired had the highest WUE. Conversely, a negative correlation was observed under low evaporative demand. Genotypes with high WUE and response to evaporative demand were also those allowing maximum light penetration into the canopy. We suggest that this caused the observed high WUE of these genotypes because leaves within the canopy had sufficient light for photosynthesis whereas we observed a lower VPD in the canopy than in open air when leaf area index reached 2.5-3, thereby decreasing transpiration.Highlights The transpiration response to evaporative demand was genetically variable and correlated to WUE: genotypes that most transpired had highest light penetration towards leaves subjected to lower VPD than in air.Competing Interest StatementThe authors have declared no competing interest.