EFFECTS OF PETROLEUM OILS ON THE CARBON DIOXIDE UPTAKE IN THE APPARENT PHOTOSYNTHESIS OF PARSNIP AND MUSTARD

Publisher Website
Google Scholar
Abstract
The herbicidal oils, petroleum naphtha, boiling range 149° to 204 °C, the naphthene–paraffin fraction of petroleum naphtha, undiluted n-dodecane, 25% p-cymene in paraffinic oil, and 15% tetrahydronaphthalene in paraffinic oil, caused an immediate decrease in apparent photosynthesis of both parsnip and mustard to near the respiration level. The photosynthesis of parsnip began to recover by 1 hour and was near 70% of normal with no visible injury by 24 hours after application of oil. With mustard, there was a slight temporary recovery during the first hour but then the photosynthesis completely ceased with the death of the leaves. Paraffinic oil containing 15% p-cymene was not selective, as the photosynthesis of mustard recovered to 40% of normal by 24 hours after application of the oil.A non-herbicidal, paraffinic oil, boiling range 204° to 260 °C, immediately decreased the apparent photosynthesis of both parsnip and mustard to the compensation point. The photosynthesis of both plants began to recover within 1 hour after application of the oil and was approaching normal by 24 hours, with no visible injury.