Water and air balance in plant propagation cells
Substrate selection and irrigation practices drive oxygen and water supply to the root zone during transplant propagation. Our objective was to describe and quantify factors and processes that affect oxygen supply to plant roots in propagation cells. The outcome was a spreadsheet model that can communicate to horticulturists and scientists the impact of management options on oxygen supply for healthy root growth during plant propagation. Published research on substrate oxygen level, porosity, and effect of compaction on volumetric air and water content (VAC and VWC) was integrated with experimental data on moisture level. A subjective moisture scale from 1 (dry) to 5 (container capacity) that is commonly used in commercial irrigation management of transplants was converted to VAC and VWC following testing of 38 substrates. From these data, oxygen and water supply could be estimated for a range of horticulture situations where substrate porosity, moisture level, temperature, oxygen saturation, and electrical conductivity were varied. Anaerobic conditions are most likely to occur with a combination of high moisture content (moisture level 5) with low air porosity (for example, a compacted substrate with fine particle size).
Fisher, P.R., Yafuso, E.J. and Huang, J. (2021). Water and air balance in plant propagation cells. Acta Hortic. 1305, 477-484
dissolved oxygen, irrigation management, moisture scale, seedling, transplant