A leaf disc method for measuring cuticular conductance

This paper describes a new method for the measurement of cuticular conductance (g(c)) using a leaf disc sealed in a specially-designed envelope, Conductances for astomatous (adaxial) and stomatous (abaxial) surfaces of beech (Fagus sylvatica L.) were determined from measurements of water flux, Leaf discs were punched out from attached leaves and placed inside individual envelopes that provided a water supply, Water flux from an exposed epidermal surface of the leaf discs was measured gravimetrically, All measurements were made under darkness, Conductance of the adaxial surface was referred to as g(c), whereas conductance of the abaxial surface was considered as a minimum leaf surface conductance (g(sur)(MIN)), The main advantage of this method is that it enables measurement of g(c) and g(sur)(MIN) from leaf samples with intact cuticles and a high relative water content (RWC) for periods of up to 12 d, Conductances of leaf discs in envelopes were compared with those of whole leaves and leaf discs without envelopes, Data demonstrating a strong positive relationship between conductance and RWC is presented.