Germination of Wheat and Alfalfa Seeds as Affected by Some Soil Urease Inhibitors1

Abstract

AbstractThe use of urease inhibitors has been proposed as a means of controlling the rate of urea hydrolysis in soils. However, application of enzyme inhibitors to soils may affect other soil processes in addition to urea hydrolysis.The purpose of this study was to determine whether soil urease inhibitors would affect the germination of wheat (Triticum aestivum L.) and alfalfa (Medicago sativa L) seeds. Soil urease inhibitors included in this study were; catechol, p‐benzoquinone, 2,5‐dimethyl‐p‐benzoquinone, hydroquinone, 1,2‐napthoquinone, benzohydroxamic acid, and phenylmercuric acetate.In the initial study, 0.003, 0.015 or 0.03 g of each inhibitor was applied to wheat or alfalfa seeds that had been placed on moist paper towelling. Germination percentage was recorded after incubating the seeds for 8 days at 20 C. At the highest rate of inhibitor application all inhibitors caused a noticeable decrease in the germination percentages of seeds of both species. Only catechol and 1,2‐napthoquinone had no effect on seed germination at the low rate of 0.003 g/plate. In a second experiment, seeds were germinated in moist soil in the presence of inhibitors applied at the rates of 100, 50, or 10 ppm of soil. No compounds affected germination when applied at 10 ppm of soil and at the higher rates, only 2,5‐dimethyl‐p‐benzoquinone caused severe reduction in the germination percentages recorded for both species.