Understanding Leaf Surface-Specific Stomatal Traits and Their Effects on Barley Grain Yield.

Adaxial-to-abaxial stomatal density and conductance ratios in spring barley penultimate leaves are positively correlated with grain yield in a pooled 3-year Estonia field dataset, with yields ranging from 2400 to 6100 kg ha -1.

• Why it matters: Grain yield variability in spring barley is linked to early-season weather, yet leaf surface-specific stomatal traits and their year-to-year consistency for yield association remain unclear.
• What they did: Across 13 barley genotypes, stomatal traits were measured on penultimate and flag leaves during a 3-year field experiment in Estonia, and correlations with grain yield were tested in pooled data and each year.
• The result: Penultimate leaf ratios of adaxial to abaxial stomatal density and conductance correlated positively with grain yield in pooled data; in 2022 and 2023, only the stomatal conductance ratio correlated, implying environment-driven, coordinated leaf-surface responses.