Nature and characterization of ammonium effects on wheat and tomato

The very significant yield increases obtained by adding NH 4 to NO 3 -supplying hydroponic cultures have, for unknown reasons, not been duplicated in soil systems. This research was conducted to consolidate and extend our knowledge of the effects of added NH 4 on plant processes, and to define the plant and culture characteristics requisite to optimal utilization of mixed N sources. Wheat (Triticum aestivum L. cv. Anza) and tomato (Lycopersicon esculentum Mill. cv. 6718 VF) were grown in solution cultures providing variables of N source (NO 3 , NH 4 , and NH 4 NO 3 ), culture buffering, and concentration of NH 4 and NH 3 (aq). Treatment effects on plant growth and composition were evaluated [...]