Variation in mesophyll conductance among Australian wheat genotypes

Area of Science:

• Plant Physiology
• Photosynthesis Research
• Crop Science

Background:

• Mesophyll conductance (gm) is crucial for CO2 diffusion to chloroplasts, impacting photosynthesis and water-use efficiency.
• Understanding genotypic variability in gm is essential for improving crop performance.

Purpose of the Study:

• To investigate genotypic variation in mesophyll conductance (gm) among wheat genotypes.
• To assess the effect of gm on water-use efficiency (A/gsw).
• To determine the influence of oxygen concentration and leaf age on gm.

Main Methods:

• Measured gm and A/gsw in eleven wheat genotypes under varying oxygen concentrations (2% and 21%).
• Analyzed the correlation between gm, photosynthetic rate, and stomatal conductance.
• Evaluated the impact of leaf age on gm in different genotypes.

Main Results:

• Significant genotypic variation in gm (0.5 to 1.0 μmol m⁻² s⁻¹ bar⁻¹) and A/gsw was observed.
• Oxygen concentration did not significantly affect gm.
• gm was correlated with photosynthetic rate but not stomatal conductance.
• Leaf age effects on gm varied among genotypes.

Conclusions:

• Substantial genotypic variation exists for mesophyll conductance in wheat.
• Mesophyll conductance is a significant determinant of photosynthetic rate and water-use efficiency.
• Careful consideration of leaf age is necessary when studying genotypic variation in gm and water-use efficiency.