Nitrogen demand, availability, and acquisition strategy control plant responses to elevated CO2

Experiment Title: “Nitrogen demand, availability, and acquisition strategy control plant responses to elevated CO2” Institutions responsible:

Texas Tech University

Experiment Description: Growth chamber pot experiment investigating the effects of nitrogen acquisition strategy and nitrogen availability on leaf and whole-plant responses to elevated atmospheric CO2 concentrations. Glycine max seedlings were grown under one of nine soil nitrogen fertilization treatments (0-630 ppm N), one of two atmospheric CO2 treatments (420, 1000 ppm CO2), and one of two inoculation treatments with symbiotic nitrogen-fixing bacteria (no inoculation, inoculation with Bradyrhizobium japonicum) in a full-factorial design. Leaf physiology and whole-plant traits were measured 7 weeks after experiment initiation.

Variables being tested: Experimental Details (factorial design, replication, lab/field/ controls, vegetation type): Data availability: Study limitations:

At least 30 leaf and whole-plant traits collected. Some notable traits include:

Carbon costs to acquire nitrogen (root carbon biomass per unit whole-plant nitrogen biomass)

Total leaf area

Organ allocation fractions (i.e. leaf mass fraction, stem mass fraction, root mass fraction)

Anet (both under common CO2, 420ppm, and under growth CO2 concentration)

Stomatal conductance

Vcmax25

Jmax25

Jmax25:Vcmax25

Cost to acquire and use nitrogen relative to water (i.e. β, calculated from leaf d13C)

Leaf Ci:Ca, calculated through leaf d13C (i.e. χ)

Leaf nitrogen per unit leaf area (Narea)

Leaf nitrogen per unit leaf biomass (Nmass)

Leaf dry biomass per unit leaf area (LMA/Marea)

Percent nitrogen fixed from the atmosphere (derived from leaf d15N)

Root nodule biomass

Root nodule biomass:root biomass

Growth chamber pot experiment. Glycine max grown under 16:8 light:dark photoperiod with 3 hour ramp between full light and dark conditions. Daytime temperatures set to 25degC and nighttime temperatures set to 17degC. Relative humidity was 50% throughout the day and night. Fertilization treatments added as modified Hoagland’s solutions such that nitrogen was the only macronutrient or micronutrient modified across fertilization treatments Data are available on Zenodo: here

A preprint for the paper is also available: here

Carbon costs to acquire nitrogen do not include carbon allocated belowground through root exudates or lost through root exudation

Short-term pot experiment- not equipped to answer questions about any long-term effects of nitrogen availability or acquisition strategy on plant responses to elevated CO2

Experiment Title:	“Nitrogen demand, availability, and acquisition strategy control plant responses to elevated CO2”		Institutions responsible: Texas Tech University
Experiment Description:	Growth chamber pot experiment investigating the effects of nitrogen acquisition strategy and nitrogen availability on leaf and whole-plant responses to elevated atmospheric CO2 concentrations. Glycine max seedlings were grown under one of nine soil nitrogen fertilization treatments (0-630 ppm N), one of two atmospheric CO2 treatments (420, 1000 ppm CO2), and one of two inoculation treatments with symbiotic nitrogen-fixing bacteria (no inoculation, inoculation with Bradyrhizobium japonicum) in a full-factorial design. Leaf physiology and whole-plant traits were measured 7 weeks after experiment initiation.
Variables being tested:	Experimental Details (factorial design, replication, lab/field/ controls, vegetation type):	Data availability:	Study limitations:
At least 30 leaf and whole-plant traits collected. Some notable traits include: Carbon costs to acquire nitrogen (root carbon biomass per unit whole-plant nitrogen biomass) Total leaf area Organ allocation fractions (i.e. leaf mass fraction, stem mass fraction, root mass fraction) Anet (both under common CO2, 420ppm, and under growth CO2 concentration) Stomatal conductance Vcmax25 Jmax25 Jmax25:Vcmax25 Cost to acquire and use nitrogen relative to water (i.e. β, calculated from leaf d13C) Leaf Ci:Ca, calculated through leaf d13C (i.e. χ) Leaf nitrogen per unit leaf area (Narea) Leaf nitrogen per unit leaf biomass (Nmass) Leaf dry biomass per unit leaf area (LMA/Marea) Percent nitrogen fixed from the atmosphere (derived from leaf d15N) Root nodule biomass Root nodule biomass:root biomass	Growth chamber pot experiment. Glycine max grown under 16:8 light:dark photoperiod with 3 hour ramp between full light and dark conditions. Daytime temperatures set to 25degC and nighttime temperatures set to 17degC. Relative humidity was 50% throughout the day and night. Fertilization treatments added as modified Hoagland’s solutions such that nitrogen was the only macronutrient or micronutrient modified across fertilization treatments	Data are available on Zenodo: here A preprint for the paper is also available: here	Carbon costs to acquire nitrogen do not include carbon allocated belowground through root exudates or lost through root exudation Short-term pot experiment- not equipped to answer questions about any long-term effects of nitrogen availability or acquisition strategy on plant responses to elevated CO2