The Effect of Various Ions on Guttation of the Tomato.

In a previous publication (6) at.tention was called to the fact that in aln experiment with tomato plants, those supplied with complete nutrient solution guttated while those in solutions lacking both nitrate and ammonium nitrogen did not guttate. At that time it was thought that the low pH of the solutions might have been responsible for the lack of guttation. Two additional observations made during the course of later work have suggested that pH alone may not have been responsible. On May 8, 1942, all plants in complete nutrient solutions that had been changed three days previously were guttating markedly while others in solutions that had not been changed were not guttating. In neither instance was the pH low. On May 19, 1942, plants that had been allowed to arow in complete solutions for 18 days but were supplied with additional calcium during the interval were t.reated as follows by adding concentrated solutions to the depleted solutins: