TY - JOUR
T1 - Linear relation between leaf xylem water potential and transpiration in pearl millet during soil drying
AU - Cai, Gaochao
AU - Ahmed, Mutez Ali
AU - Dippold, Michaela A.
AU - Zarebanadkouki, Mohsen
AU - Carminati, Andrea
N1 - Publisher Copyright:
© 2020, Springer Nature Switzerland AG.
PY - 2020/2/1
Y1 - 2020/2/1
N2 - Aims: As soil dries, the loss of soil hydraulic conductivity limits water supply to the leaves, which is expected to generate a nonlinear relationship between leaf water potential (ψleaf) and transpiration (E). The effect of soil drying and root properties on ψleaf and E remains elusive. Methods: We measured E and ψleaf of pearl millet for varying E and soil moisture using a root pressure chamber. A model of water flow in soil and plant was used to fit the ψleaf (E) relationship. Results: The relation between ψleaf and E was linear at all soil moistures. The slope of ψleaf (E) increased with decreasing soil moisture due to the decreasing soil-root conductance. The fact that the relation remained linear also in dry soils and high E is surprising. Indeed, it indicates that the gradients in soil water potential (ψsoil) were small, probably because of the large root surface (13.5 cm cm−3) active in water uptake. ψleaf at E = 0 was less negative than ψsoil, indicating a more negative osmotic potential in the xylem than in the soil. Conclusions: We propose that the linearity between ψleaf and E and the high ψleaf (E = 0) compared to ψsoil support transpiration in drying soils.
AB - Aims: As soil dries, the loss of soil hydraulic conductivity limits water supply to the leaves, which is expected to generate a nonlinear relationship between leaf water potential (ψleaf) and transpiration (E). The effect of soil drying and root properties on ψleaf and E remains elusive. Methods: We measured E and ψleaf of pearl millet for varying E and soil moisture using a root pressure chamber. A model of water flow in soil and plant was used to fit the ψleaf (E) relationship. Results: The relation between ψleaf and E was linear at all soil moistures. The slope of ψleaf (E) increased with decreasing soil moisture due to the decreasing soil-root conductance. The fact that the relation remained linear also in dry soils and high E is surprising. Indeed, it indicates that the gradients in soil water potential (ψsoil) were small, probably because of the large root surface (13.5 cm cm−3) active in water uptake. ψleaf at E = 0 was less negative than ψsoil, indicating a more negative osmotic potential in the xylem than in the soil. Conclusions: We propose that the linearity between ψleaf and E and the high ψleaf (E = 0) compared to ψsoil support transpiration in drying soils.
KW - Balancing pressure
KW - Pennisetum glaucum (L.) R.Br
KW - Plant hydraulic conductance
KW - Root pressure chamber
KW - Stomatal conductance
KW - Vapor pressure deficit
UR - http://www.scopus.com/inward/record.url?scp=85077635004&partnerID=8YFLogxK
U2 - 10.1007/s11104-019-04408-z
DO - 10.1007/s11104-019-04408-z
M3 - Article
AN - SCOPUS:85077635004
SN - 0032-079X
VL - 447
SP - 565
EP - 578
JO - Plant and Soil
JF - Plant and Soil
IS - 1-2
ER -