Studies on the Ammonium Tolerance of Some Cultivated Solanaceae1,2

Tomato, tobacco, pepper, petunia, and eggplant were screened for their tolerance to continuous (NH 4 ) 2 SO 4 applications. Stem lesions, analogous to those which appear on tomato during ammonium toxicity, were formed on eggplant but not on the other species. Of the plants tested, tobacco was the most tolerant to applications of (NH 4 ) 2 SO 4 . Potassium applications increased the ammonium concentration of tobacco tissues but lowered the ammonium concentration of tomato tissues. Diamine concentrations were increased by the application of (NH 4 ) 2 SO 4 . The application of KCl decreased the putrescine concentration of tobacco and increased the concentration of cadaverine in tomato and tobacco. The application of putrescine-2HC1 in aqueous solution to cut stem ends of axillary shoots of tomato and tobacco induced the formation of stem lesions analogous to those formed by the (NH 4 ) 2 SO 4 fertilization of tomato. It is postulated that the tolerance of tobacco to stem lesion formation is related to putrescine utilization in nicotine synthesis.