Nutrient Deprivation Affects Xylem Sap Flow and Water Channel Function in Tomato Plants

Abstract

Heat-balance sap-flow gauge was used to measure xylem sap flow through the main stem of tomato (Lycopersicum esculentum Mill. cv. Young-Kwang) plants grown under nitrogen-or phosphorus-deficient nutrient solutions for nine days. Nitrogen deficient plants transported less sap than phosphorus deficient plants. Moreover, the effect of nitrogen deficiency on xylem sap flow was rapid, appearing within one day of treatment. Addition of mercury to nutrient solution induced immediate and drastic reduction in sap flow of both control and nutrient deprived plants. Subsequent use of dithiothreitol (DTT), however, did not recover sap flow in nutrient deprived plants. This suggests that the alteration in the characteristics of water channel was due to nutrient deficiencies.