Characterizing Root Morphology, Water and Nitrogen Uptake of Fibrous-Root and Taproot Crops Under Transparent Soil

Root morphology and uptake capacity are increasingly investigated as indicators of crop performance, yet their characterization remains challenging in laboratory. Soil or sand are opaque to most forms of radiation, while transparent medium fails to provide soil-relevant characteristics. Transparent soil (TS) is specifically designed to support root growth in the presence of air, water, and nutrients, enabling in situ root phenotyping. An indoor experiment was conducted, involving three growth mediums (natural soil, TS, hydroponics), two fibrous-root crop species (wheat, maize) and two taproot crop species (cotton, soybean), to evaluate the impact of TS on root morphology and water and nitrogen uptake of crops with different root types. Results showed that, compared with the average difference between hydroponics and natural soil, the average difference in root morphology and water and nitrogen uptake of maize between TS and natural soil was significantly decreased, as well as for cotton, soybeans, and wheat in turn. It was concluded that compared to those developed in hydroponics, the root developed in TS was significantly more similar to those developed in natural soil. Yet such similarity varied across crop species, with no clear correlation to root types. These findings provide a theoretical foundation for promoting the application of TS.