The

Area of Science:

• Plant Science
• Agricultural Science
• Genetics

Background:

• Grain size is a key factor in wheat yield.
• The ubiquitin receptor DA1 negatively regulates grain size.
• Understanding DA1's role is crucial for improving wheat yield potential.

Purpose of the Study:

• To investigate if the da1 mutant's increased thousand grain weight translates to higher wheat yield.
• To determine if da1 mutants utilize elevated CO2 (eCO2) more effectively for grain filling.
• To analyze the impact of da1 mutation and eCO2 on yield components and grain quality.

Main Methods:

• Two-factorial mixed-model analysis of yield-related traits, biomass, and grain quality.
• Comparison of da1 mutant wheat under ambient and eCO2 conditions.
• Analysis of grain dimensions and yield components.

Main Results:

• The da1 mutation increased grain size but reduced grains per plant and per spike, resulting in unchanged total grain yield.
• Elevated CO2 increased yield and grain number additively and independently of the da1 mutation.
• eCO2, but not da1, negatively impacted grain quality, reducing macro- and microelement concentrations.

Conclusions:

• The da1 mutation's benefit to grain size does not enhance overall wheat yield due to trade-offs with grain number.
• Interactions between da1 genotype and eCO2 reveal limitations in current wheat yield potential.
• Overcoming the trade-off between grain size and number is essential for increasing wheat yield.