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 bee n reluctant to exploit this relationship because the equipment required is either too costly or too slow for assessing large breeding populations. Thi s study compared a new hand-held viscous-flow porometer against a steady-st ate diffusion porometer for leaf conductance measured on progeny derived fr om widely varying conductance wheats,'Quarrion' and 'Genaro 81'. Leaf condu ctance values from the two instruments were related linearly, and significa nt phenotypic (r(p) = 0.76-0,90**) and genotypic (r(g) = 0.75-0.98**) corre lations were obtained across sampling days, suggesting the new porometer is a robust predictor of leaf diffusive conductance. The enhanced speed of th e new viscous-dow porometer in evaluating variation for leaf conductance sh ould enable wheat breeders to screen large breeding populations for leaf co nductance more efficiently.