Data from: Increasing photosynthetic benefit with decreasing irrigation frequency in an Australian temperate grassland exposed to elevated carbon dioxide
Data files
Jan 20, 2025 version files 514.14 KB
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README.md
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TasFACE2_Lolium_perenne_responses_to_eCO2_and_irrigation.xlsx
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Abstract
Elevated atmospheric CO2 (e[CO2]) often enhances plant photosynthesis and improves water status. However, the effects of e[CO2] vary significantly and are believed to be influenced by water availability. With the future warmer climate expected to increase the frequency and severity of extreme rainfall, the response of plants to e[CO2] under changing precipitation patterns remains uncertain. We examined the effects of e[CO2] and different irrigation regimes on perennial ryegrass in a free-air CO2 enrichment (FACE) experiment. Immediately after irrigation, the mean net photosynthetic rate was 21.2% higher under e[CO2] compared with ambient conditions. This benefit increased over time, reaching a 31.3% higher rate as days since watering increased, indicating a substantial increase in photosynthetic benefit with longer intervals between watering. Mean stomatal conductance was 21% lower in ryegrass under e[CO2] immediately after irrigation compared with ambient plots. However, the reduction in stomatal conductance under e[CO2] decreased as the interval between irrigation events increased, showing no difference 7–10 d after an irrigation event. These results imply that plants benefit most from carbon fertilization, assimilating relatively more carbon and losing less water, during periods with less frequent rainfall. These findings have significant implications for understanding leaf-level responses to climate change.
README: Increasing photosynthetic benefit with decreasing irrigation frequency in an Australian temperate pasture exposed to elevated carbon dioxide
The first sheet contains the gas exchange data i.e. net carbon assimilation and stomatal conductance and the second worksheet is the water potential data. The third worksheet is soil water content and the fourth worksheet is leaf area index data.
Treatments
- CO2 treatments were ambient at 400 ppm and elevated at 550 ppm. Watering treatments were watered every 3, 5, and 10 days with the overall amount being the same over 30 days. 12 individual study plots (rings) were used 6 at elevated CO2 and 6 at ambient CO2.
The study species was Lolium perenne.
Measurements
- Gas exchange, water potential, soil water content and leaf area index was measured.
Description of the data and file structure
The following column names occur in all sheets:
Date - date on which the variable was measured.
Ring - plot measured
CO2 - CO2 concentration, ambient or elevated.
Water - irrigation treatment, 3, 5, or 10 days.
Gas exchange
- Anet is net photosynthetic rate (µmol m-2 s–1)
- gs is stomatal conductance (mol m-2 s-1)
- VpdL is vapour pressure deficit (kPa) of the leaf.
- DSW refers to days since water i.e. since the last irrigation event.
Water potential
- PSI (per square inch) is a measure of water potential and is converted to Mpa (megapascals) which is the conventional way of reporting water potential.
- Time.of.day is when measurements were taken either pre-dawn or midday.
Soil water content
- SWC.MIN is daily minimum, SWC.MAX is daily maximum and SWC.MEAN is daily mean volumetric soil water content (cm-3/cm-3).
- Cycle refers to the watering cycle which changes each time a watering event occurs.
Leaf area index (LAI)
- Leaf area index was measured at the three leaf stage mol (m-2/m-2).
Sharing/access information
Data
- Data not stored elsewhere and not derived from other sources.
Methods
In a Free-Air Carbon Enrichment site (FACE) in Tasmania, we investigated pasture grass (perennial ryegrass) responses to elevated CO2 and irrigation frequency. We assessed the impacts of treatments on gas exchange, water relations, leaf area index and soil water content on perennial ryegrass over one year.