Dataset Photosynthesis parameters

This dataset contains the raw physiological data underlying the study "Photosynthetic Coordination, Not Maximum Carbon Gain, Defines Drought Resilience in Mediterranean Olive-Grove Ground Covers". It includes gas-exchange, chlorophyll fluorescence, and photosynthesis–irradiance (P–I) light-response measurements obtained from nine Mediterranean olive-grove ground-cover species/genotypes (Calendula arvensis, Vicia villosa, Brachypodium hybridum, Brachypodium distachyon and Sinapis alba) grown under three climate scenarios (current climate (EC) and two future warming/elevated CO₂ scenarios (ECC1 and ECC2)) and three water regimes (well-watered (WW), moderate drought (MD) and severe drought (SD)). The dataset comprises measurements of net photosynthetic rate (Pn), electron transport rate (ETR), PSII quantum efficiency (ΦPSII), and intercellular CO₂ concentration (Ci). Leaf gas exchange and chlorophyll fluorescence were measured simultaneously on fully expanded mature leaves using a LI-6800 portable photosynthesis system equipped with a 6800-01 fluorometer and transparent leaf chamber (LI-COR Biosciences, Lincoln, NE, USA), following Martos de la Fuente et al. (2023). Measurements were performed on three biological replicates per genotype × treatment × scenario combination. Chamber conditions were maintained at 40% relative humidity, 21 °C leaf temperature and the CO₂ concentration corresponding to each climate scenario: 415 ppm for EC and 600 ppm for ECC1 and ECC2. Plants were dark-adapted overnight before fluorescence measurements. Instantaneous water-use efficiency (WUE=Pn/E) and intrinsic water-use efficiency (WUEi=Pn/gsw ) were calculated at light-saturating PPFD from directly measured gas-exchange values (Farquhar & Sharkey, 1982). These data provide a comprehensive resource for investigating the physiological mechanisms underlying photosynthetic coordination and drought resilience in candidate ground covers for Mediterranean olive groves under future climate conditions.