Deep rooting and drought screening of cereal crops: A novel field-based method and its application

Lack of water is a major limitation to crop production, particularly where roots of cereal crops are not able to access water stored in the subsoil. One way that roots penetrate the subsoil to access water is by following natural biopores – paths created by roots from previous crops, or as burrows from soil fauna. Burying a mesh layer horizontally in the soil can prevent root penetration to the subsoil. We used this technique with the novel modification that the mesh was punctured to create a defined number of holes per unit area; controlling access to the subsoil and to the water therein. The holes were of similar size to biopores.Five barley genotypes were late sown and grown during a dry summer. Monitoring of crop performance included plant height, leaf area and Normalized Difference Vegetation Index (NDVI). Crops grown with unrestricted access to the subsoil outperformed crops with limited or no access to the subsoil. Crops grown with controlled, limited access to the subsoil performed better than those with no access and the performance was generally related to amount of access. Changes in soil water content were in line with the amount of root access to the subsoil; confirming the association between subsoil water and crop growth and development in drought conditions. While there were no significant interactions between the genotypes and treatments used here, the method offers promise for studying some aspects of cereal ecophysiology and could be used to identify promising germplasm that may be of interest in plant breeding. Further testing is required to adapt the method for a wider range of crop types and soil conditions and testing for crops grown to maturity.