Table 1.

Pearson correlation coefficient values between WUE, VPD, and assimilation parameters in winter oat (2021, Debrecen).

	Ci	GSW	Transp	Tleaf-Tair	WUE	VPDleaf
Ass	−0.355 **	0.876 **	0.888 **	−0.667 **	0.447 **	−0.698 **
Ci	1	0.440 **	0.328 **	−0.461 **	−0.745 **	−0.548 **
GSW	0.440 **	1	0.937 **	−0.801 **	0.058	−0.873 **
Transp	0.328 **	0.937 **	1	−0.789 **	0.013	−0.706 **
Tleaf-Tair	−0.461 **	−0.801 **	−0.789 **	1	0.103 *	0.686 **
WUE	−0.745 **	0.058	0.013	0.103 *	1	−0.108 *

Ass: photosynthesis rate; Ci: intercellular CO₂ level; GSW: stomatal conductance to water vapor; Transp: transpiration; T_leaf-T_air: difference between leaf and air temperature; WUE: water use efficiency; VPD_leaf: vapor pressure deficit on the leaf. *: the correlation is significant at p = 5%; **: the correlation is significant at p = 1%.