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Etiology

Increased Growth of Nicotiana glutinosa as Partially Related to Accumulation of Ammonium-Nitrogen in Soil Fumigated with Methyl Bromide. David E. Millhouse, Graduate research assistant, Department of Plant Pathology, University of California, Riverside 92521, Senior author’s present address: Research Laboratories, Rohm and Haas Company, Springhouse, PA 19477; Donald E. Munnecke, professor, Department of Plant Pathology, University of California, Riverside 92521. Phytopathology 69:793-797. Accepted for publication 16 February 1979. Copyright 1979 The American Phytopathological Society. DOI: 10.1094/Phyto-69-793.

Biological and chemical changes were measured in soil fumigated for various periods with methyl bromide (27,000 μl/L air) in a moving air-stream. Height of Nicotiana glutinosa plants grown in fumigated soil increased as the period of fumigation increased above 16 hr. Increased growth was correlated with elimination of a coenocytic fungus from the roots of plants grown in soil fumigated for longer than 4 hr and with elimination of microorganisms other than recognized fungal pathogens. Increased growth was correlated with an increase in inorganic nitrogen (primarily ammonium) in soil fumigated for 16 hr or longer. Concentrations of various plant nutrients were determined in tissues of 35-day-old N. glutinosa plants grown in fumigated soil. Only nitrogen was closely correlated with increased growth, although high concentrations of copper, manganese, zinc, and phosphorus in plants grown in soil fumigated for 128 hr may have accounted for some increased growth.