Data. Traditional rye varieties exhibit drought tolerance traits but maintain lower yields than modern varieties under drought stress

Absolute_values.xlsx contains experimentally obtained yield trait, isotopic, and chlorophyll index data for winter rye. Columns include: Variety; Treatment, where C = control/well-watered and S = drought-stressed; SLW [g], straw and leaves weight of main stems; GW [g], grain weight per spike; GN [pcs], grain number per spike; AB [g], aboveground biomass per plant; TGW [g], thousand-grain weight calculated as TGW = (GW/GN) × 1000; HI, harvest index calculated as HI = GW/(SG + SLW), where SG is spike weight including grains; CI_F [Dualex units], chlorophyll index measured by Dualex 4 Flav; δ13C [‰], stable carbon isotope composition relative to VPDB; and δ15N [‰], stable nitrogen isotope composition relative to Air N2. Values are reported with the stated measurement precision and units. Relative_values-RCC.xlsx contains relative changes in drought-stressed treatments compared with controls (RCC), calculated from Absolute_values.xlsx using equation (3) in the article.