The Effects of Potassium on Ammonium Nutrition of Tomato (<i>Lycopersicon esculentum</i> Mill.)¹

Abstract

Abstract Tomato plants ( Lycopersicon esculentum Mill.) grown in pot culture in the greenhouse were easily injured by continuous, prolonged application of (NH 4 ) 2 SO 4 . When an equivalent amount of K was supplied with the NH 4 , plant injury due to excessive NH 4 was prevented. The presence of K in the NH 4 culture system enhanced growth and restricted total N and NH 4 ‐N accumulation. The magnitude of the restriction of N constituents suggests that the ameliorating K effect was due in part to a K:NH 4 competition for uptake but principally to the enhancement of NH 4 assimilation.