Spectral responses of pot-grown plants to displacement of soil oxygen

Abstract

Detection of leaking gas pipelines is important for safety, economic and environmental reasons, and remote sensing of vegetation offers the potential to identify gas leakage through spectral responses in the plants growing above. Pot-scale investigations were carried out to determine the effects of soil-oxygen displacement using natural gas, argon, nitrogen and waterlogging on the overlying vegetation and to determine whether changes in spectral characteristics were specific to natural gas or were a generic response to soil-oxygen displacement. Leaves responded to soil-oxygen displacement by increased reflectance in the visible wavelengths and changes in the position and shape of the red edge. The red edge of control plants shifted towards longer wavelengths as they matured, while the red edge of treated plants remained stationary, indicating an inhibition of maturing. Bean and barley exhibited different shapes in the peaks at the red edge. Argon and waterlogging produced greater responses than natural gas, which was administered non-continuously. These results suggest that the response to natural gas is generic to soil-oxygen deficiency rather than specific to this agent. Hence, although it might be possible to detect leaking gas by remote sensing of vegetation, ancillary information such as pipeline maps would be required to discriminate natural gas responses from those due to other stresses.