Effects of urease inhibitors on germination of seeds in soil

Abstract

The effects of 23 urease inhibitors on germination of seeds in soil were investigated. The urease inhibitors tested were 2/5‐dimethyl‐l,4‐benzoquinone, 1/4‐benzoquinone, hydroquinone, 2,5‐dichloro‐l,4‐benzoquinone, phenylmercuric acetate, catechol, phenylphosphorodiamidate, phosphoric triamide, N‐(4‐nitrophenyl)‐phosphoric triamide, N‐(diaminophosphinyl)benzeneacetamide, 4‐chloro‐N‐(diaminophosphinyl)benzamide, N‐3‐(trifluoromethyl‐phenyl)phosphoric triamide, 4‐fluoro‐N‐(diaminophosphinyl)‐benzamide/ 4‐cyano‐N‐(diaminophosphinyl)benzamide, N‐(diamino‐phosphinyl)‐3‐pyridinecarboxamide, N‐(diaminophosphinyl)‐benzamide, N‐phenylphosphoric triamide, phosphorodiamidic acid, N‐(n‐butyl)thiophosphoric triamide, thiophosphoric triamide, 4‐chlorophenylphosphorodiamidate, 2,4‐diphenoxy‐2,4,6,6‐tetraaminocyclotriphosphazene, and 2‐phenoxy‐2,4,4,6,6‐pentaaminocyclotriphosphazene. Germination tests were performed with seeds of alfalfa (Medicago sativa L.), wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), sorghum Sorghum bicolor (L.) Moench], and corn (Zea mays L.).

None of the inhibitors tested affected seed germination when applied at the rate of 250 μg g^‐1 soil. One inhibitor (2,5‐dimethyl‐l,4‐benzoquinone) affected seed germination when applied at the rate of 500 μg g^‐1 soil, and three inhibitors (2,5‐dimethyl‐1,4‐benzoquinone, 1,4‐benzoquinone, and hydroquinone) affected seed germination when applied at the rate of 2500 μg g^‐1 soil. None of the other inhibitors tested affected seed germination when applied at the rate of 500 or 2500 μg g^‐1 soil.