New Phytologist

New Phytologist Supporting Information

Article title: Plant responses to rising evaporative demand

Authors: Charlotte Grossiord, Thomas N. Buckley, Lucas A. Cernusak, Kimberly A. Novick, Benjamin Poulter, Rolf T.W. Siegwolf, John S. Sperry, Nate G. McDowell

Acceptance date: 4 February 2020.

The following Supporting Information is available for this article:

Figure S1. Impact of increased VPD on leaf-level photosynthesis.

Figure S1. Response of net CO2 assimilation rate (A) to leaf-to-air vapor pressure deficit (VPDL) in four species. A is expressed relative to its value at VPDL = 1 kPa, which was estimated by fitting 2^nd order polynomials to each dataset. Lines shown above are 2^nd order polynomials fitted to the normalized data: S. townsendii (y = -0.0122×x² – 0.0192×x + 1.031; r² = 0.986); Z. mays (y

= -0.0167×x² + 0.0195×x + 0.997; r² = 0.993); R. communis (y = -0.0479×x² + 0.0229×x + 1.004; r²

= 0.994); N. tabacum (y = -0.0163×x² – 0.0819×x + 1.098; r² = 0.997). Data for S. townsendii are from Long & Woolhouse (1978); all other data are from Dai et al., (1992).

VPD_L /kPa

0 1 2 3 4

net CO 2 assimilation rate (relative to value at VPD L = 1 kPa)

0.2 0.4 0.6 0.8 1.0 1.2

Spartina townsendii Zea mays

Ricinis communis Nicotiana tabacum

References

Dai Z, Edwards GE, Ku MSB. 1992. Control of photosynthesis and stomatal conductance in Ricinis communis L. (castor bean) by leaf to air vapor pressure deficit. Plant Physiol 99:1426- 1434

Long SP, Woolhouse HW. 1978. The responses of net photosynthesis to vapor pressure deficit and CO2 concentration in Spartina townsendii (sensu lato), a C4 species from a cool temperate climate. Journal of Experimental Botany 29:567-577