Some aspects of internal aeration in wetland plants

Gaynard, Thomas Joseph

Abstract

The thesis describes a study of certain leaf, stem and root factors expected to influence internal aeration in the wetland plant Eriophorum angustifolium Honck and Oryza sativa L. The effectiveness of the soil as an oxygen sink was also investigated.

Radial oxygen flux from roots was monitored polarographically and the data manipulated to calculate internal diffusive resistances and root apical oxygen concentration. Analysis of the internal atmosphere was carried out using a gas analyser constructed for this purpose. An existing electrical analogue system was modified and improved, and was used to interpret experimental data, and to carry out certain investigations per se.

Oxygen enters the Eriophorum plant exclusively by the stomata , which normally offer no resistance to oxygen diffusion; very few stomata at the leaf base are necessary for adequate aeration of the root system. Non-metabolic resistance is low in all organs, including the root-shoot junction and lacunar diaphragms; effective resistance was slightly higher due to respiration, but leakage effects were undetectable. Resistance in the apical root wall was significant. The concept of effective resistance was shown to be more complex than was realized previously.

Critical oxygen pressure (C.O.P.) for respiration in the intact plant was monitored in the cortical gas spaces of the root apex and was about 2- 3%. Roots ceased elongation below the critical pressure but remained viable if the leaves were kept above the C.O.P. Results suggested that anaerobic respiration could maintain root viability but would not allow elongation.

In totally submerged plants in the dark internal oxygen is exhausted in about 1h. In submerged and partially submerged plants photosynthesis can considerably boost internal oxygen levels, the effect being related to CO₂ availability and t he degree of submergence.

The soil was shown to be an effective sink for internal root oxygen, and the difference in potential rooting depths between wetland and non- wetland plants was demonstrated by modelling.

Citation

Gaynard, T. J. (1979). Some aspects of internal aeration in wetland plants. (Thesis). University of Hull. Retrieved from https://hull-repository.worktribe.com/output/4217498

• Thesis Type: Thesis
• Deposit Date: Dec 18, 2015
• Publicly Available Date: Feb 23, 2023
• Keywords: Botany
• Public URL: https://hull-repository.worktribe.com/output/4217498
• Additional Information: Department of Botany, The University of Hull
• Award Date: May 1, 1979