Effects of Petroleum Oils on the Carbon Dioxide Output in Respiration of Parsnip and Mustard.

Abstract

The effects of several oils on the respiration of a resistant plant, Pastinaca sativa and of a susceptible plant, Brassica kaber Wheel, var. pinnatifida Stokes were determined by means of an infrared microanalyzer. A non-herbicidal, paraffinic oil (boiling range 204-260[degree] C) caused a slight decrease of short duration in respiration of both plants, followed by an immediate increase and a gradual return to nor-mal within 24 hrs. with no apparent injury. The herbicidal oils, petroleum naphtha (boiling range 149-204[degree]C), 300 ppm. of Hg in petroleum naphtha, 450 ppm. of Hg in paraffinic oil, a naphthene fraction, a naphthene-paraffin fraction, n-dodecane and 20% p-cymene in n-dodecane, all produced a sharp rise in respiration of parsnip followed by a gradual return to normal within 24 hrs. with no visible injury; but when applied to mustard a similar sharp rise in respiration was followed by a marked reduction and death of the plant. A concentrate of 3000 ppm. of Hg in paraffinic oil killed both plants. Under anaerobic conditions, the paraffinic oil had no effect on the respiration of parsnip while the petroleum naphtha caused an increase, indicating that the paraffinic oil stimulated the aerobic oxidation processes while the petroleum naphtha stimulated both the aerobic oxidation processes and the glycolytic processes of respiration.