The Influence of Phosphorus Deficiency on the Transpiration of Arctium Minus Bernh.

Summary The effect of phosphorus deficiency on the transpiration of Arctium minus was investigated. The transpiration rate of the phosphorus‐deficient plants was lower than that of the controls. This situation was reversed after wilting which depressed the transpiration rate of the control plants. The ratio of light to dark transpiration was higher in the control plants, and covering the abaxial surface of their leaves with petroleum jelly caused a proportionately greater reduction in their rate of transpiration. The leaves of the deficient plants were composed of smaller cells than those of the controls. An examination of leaf surfaces showed that those of the deficient plants were covered by a much denser layer of hairs. It was concluded that the difference in the rate of transpiration was probably connected with stomatal functioning.