A hand-held porometer for rapid assessment of leaf conductance in wheat

Grain yield in bread wheat (Triticum aestivum L.) has been associated with variation in leaf stomatal conductance. However, breeding programs have been reluctant to exploit this relationship because the equipment required is either too costly or too slow for assessing large breeding populations. This study compared a new hand-held viscous-flow porometer against a steady-state diffusion porometer for leaf conductance measured on progeny derived from widely varying conductance wheats, 'Quarrion' and 'Genaro 81'. Leaf conductance values from the two instruments were related linearly, and significant phenotypic (r(p) = 0.76-0.90**) and genotypic (r(g) = 0.75-0.98**) correlations were obtained across sampling days, suggesting the new porometer is a robust predictor of leaf diffusive conductance. The enhanced speed of the new viscous-flow porometer in evaluating variation for leaf conductance should enable wheat breeders to screen large breeding populations for leaf conductance more efficiently.