Small rhizotrons have been occasionally used to study root growth of (wetland) plants (as related to soil properties) under waterlogged / flooded conditions (e.g. Busch et al. 2006, see Figure). However, hydroponic root boxes are not yet commercially available - hampering research on the "hidden half" of wetland and waterlogged ecosystems. Many studies thus use pots, which, however, allow e.g. measurements on root growth and spatial patterning of soil properties only at harvest time. Also large tanks holding several pots with plants have been used, but often at the cost of missing independent replicates. As of customer demand, particular for potential studies on rice root systems, Vienna Scientific is thus currently testing hydroponic rhizobox designs allowing to study roots and soil parameters under independently flooded conditions. We aim for developing a robust, cost-effective floodable rhizobox design which allows access to roots and soil via a removeable (transparent) front and/or back plate, the convenient adjustment of water levels by a (bottom) drainage system (with outlets at the side), and provides a savely sealed experimental system effectively preventing leakages. Stay tuned for details!
The term waterlogging is used to refer to (super) saturation of the soil beyond field capacitiy. Beside in natural wetlands, water logging occurs when the infiltration of water from rainfall or flooding exceeds the rate of drainage and evapotranspiration. Diffusion of gases, notably of O2, is ∼10k-times slower in water than in air, leading to a rapid O2 depletion in waterlogged soils - as diffusion fails to keep pace with repiratory demand by roots and microbes. Oxygen deficiency in the rooting zone thus affects plant growth directly and rapidly by limiting aerobic respiration. Many species well adapted to waterlogging, such as rice, alder or Cyperaceae species, have aerenchyma formed in root tissues that allows the root-internal transport of oxygen. Others such as mangroves tap into oxygen above water levels by developing special organs. These adaptations can (at least partly) compensate for O2 shortages in the soil and support root aerobic respiration. A large body of work has thus focused on the development and functional role of aerenchymatous roots under waterlogged conditions. On the other hand, quantification of responses of "normal" (lateral) roots to waterlogging of "non-wetland" plants / crops has still been often overlooked. This is surprising, as extremes in water availability world-wide (both wet and dry) will increase under future climate conditions, and many management measures (e.g. heavy machinery used for harvests) facilitate soil compaction - compaction rendering soils more prone to waterlogging by reducing pore spaces. In addition to direct effects by O2 depletion, many other soil biochemical processes are affected by waterlogging, resulting i.a. in large alterations in nutrient availabilities. It seems thus key, that root and soil processes under temporal waterlogging recieve greater attention by researchers world-wide. Vienna Scientific aims to contribute the technical means - by developing effective hydroponic rhizobox systems - enabeling the easier set-up of research programs on the topic.