Observations on dew and the water relations of wheat

Abstract

Water potentials of ears of Kopara wheat at 0900 h averaged 13.5 bars in non-irrigated plots and –6.2 bars in irrigated plots on a day with low levels of solar radiation. On a similar day 5 days later the mean water potential of ears from non-irrigated plots was –8.1 bars, whereas ears from irrigated plots recorded a mean value of –2.3 bars. The higher water potential was attributed to dew deposited on the wheat. Water potentials of ears were related to environmental parameters which were likely to be associated with the frequency and intensity of dcwfall. It was concluded that the greatest proportion of the dew originated from the condensation of atmospheric water vapour. The significance of dew to the water economy of wheat in Canterbury is discussed.