A LEAF DISC METHOD FOR MEASURING CUTICULAR CONDUCTANCE

This paper describes a new method for the measurement of cuticular con ductance (g(c)) using a leaf disc sealed in a specially-designed envel ope, Conductances for astomatous (adaxial) and stomatous (abaxial) sur faces of beech (Fagus sylvatica L.) were determined from measurements of water flux, Leaf discs were punched out from attached leaves and pl aced inside individual envelopes that provided a water supply, Water f lux from an exposed epidermal surface of the leaf discs was measured g ravimetrically, All measurements were made under darkness, Conductance of the adaxial surface was referred to as g(c), whereas conductance o f the abaxial surface was considered as a minimum leaf surface conduct ance (g(sur)(MIN)), The main advantage of this method is that it enabl es measurement of g(c) and g(sur)(MIN) from leaf samples with intact c uticles and a high relative water content (RWC) for periods of up to 1 2 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 .