Soil Oxidation-Reduction in Wetlands and Its Impact on Plant Functioning

Abstract

Soil flooding in wetlands is accompanied by changes in soil physical and chemical characteristics. These changes include the lowering of soil redox potential (Eh) leading to increasing demand for oxygen within the soil profile as well as production of soil phytotoxins that are by-products of soil reduction and thus, imposing potentially severe stress on plant roots. Various methods are utilized for quantifying plant responses to reducing soil conditions that include measurement of radial oxygen transport, plant enzymatic responses, and assessment of anatomical/morphological changes. However, the chemical properties and reducing nature of soil environment in which plant roots are grown, including oxygen demand, and other associated processes that occur in wetland soils, pose a challenge to evaluation and comparison of plant responses that are reported in the literature. This review emphasizes soil-plant interactions in wetlands, drawing attention to the importance of quantifying the intensity and capacity of soil reduction for proper evaluation of wetland plant responses, particularly at the process and whole-plant levels. Furthermore, while root oxygen-deficiency may partially account for plant stress responses, the importance of soil phytotoxins, produced as by-products of low soil Eh conditions, is discussed and the need for development of methods to allow differentiation of plant responses to reduced or anaerobic soil conditions vs. soil phytotoxins is emphasized.

Root Radial Oxygen Loss and the Effects on Rhizosphere Microarea of Two Submerged Plants

“…As oxygen is leaking from the roots, it is continuously consumed by microbial respiration and reoxidation of reduced compounds such as NH 4 + and Fe 2+ in sediment [30][31][32]. In this experiment, the rhizosphere of H. verticillata had higher NH 4 + and Fe 2+ than V. spiralis, which were both significantly lower than the control sediment (Fig.…”

United States Gulf of Mexico Coastal Marsh Vegetation Responses and Sensitivities to Oil Spill: A Review

“…Therefore, if oil covers leaf surfaces, it can easily block the stomatal pores. Blocking oxygen diffusion to the roots leads to initiation of root oxygen stress, which is a primary factor limiting plant growth, survival, and functioning in wetlands [3,[35][36][37][38]. In addition, oil that covers plant leaves causes temperature stress due to blocking the leaf transpiration mechanism [2,7,39].…”

Phosphorus adsorption after drainage in two soil classes

“…The stable Eh values at 110 mV and 20 mV for Albaqualf and Argiaquoll, respectively, characterize an anoxic environment (Tian-Yen, 1985). The lower the Eh value, the higher will be the concentration of reduced compounds, i.e., the higher the reduction state of the soil (Pezeshki & DeLaune, 2012). It is possible that the lowest Eh value in Argiaquoll was due to a higher concentration of organic matter (Figure 2).…”