Transpiration of Helxine solierolii and the effect of drought.
In 2 glasshouse experiments, one in summer, the other in winter, Helxine soleirolii growing in John Innes No. 1 potting compost was either irrigated so that the soil-water deficit never exceeded 4 mm or was left unirrigated. The resistance to water transport between the near-surface soil layers and transpiring leaves was negligible when the daily transpiration rate of irrigated plants was 0-4 mm. Changes in the transpiration rate of plants in drying soil, relative to that of irrigated ones, were attributed to changes in the water-vapour conductance of the stomata resulting from changes in soil-water potential these 2 factors being linearly related over a range of potentials from -1 bar to less than -20 bars.