Effect of glufosinate on plant seedlings grown with different nitrogen sources

The phytotoxic activity of glufosinate and the amount of ammonia accumulated during the application of the herbicide were compared among cucumber, rice and corn seedlings. The plant seedlings were grown in Kasugai's nutrient solution until the 1-st true leaf stage (cucumber) and the 2.8 leaf stage (rice and corn). The roots of the plant were immersed in a glufosinate solution for one hour. Growth of the seedlings was suppressed and chlorosis of leaf margins was observed after the application of more than 2mM glufosinate. Effect of glufosinate on the plant seedlings grown with different nitrogen sources (NH+4-N, NO-3-N or none) was also analyzed. Although the rate of growth inhibition differed slightly with the difference in the nitrogen sources in the medium, the growth of all the plant species was retarded by the application of 2mM glufosinate and chlorosis of the leaves was observed at 2 days after treatment. The ammonia content increased in all the plant seedlings after the herbicide treatment, suggesting that the type of chemical and amount of absorbed nitrogen did not contribute to the herbicide action of glufosinate. Since a C4 plant (corn) was injured in the same way as C3 plants (cucumber and rice), it is assumed that photorespiration also may not be related to the herbicide action.