Root growth response of spring wheat (Triticum aestivum L.) and mallow (Malva sylvestris L.) to biopore generating precrops

Summary

Little is known about root growth in biopores. The aim of this study was to quantify differences of root-length density (RLD) in biopores between a tap root system (mallow) and a fibrous root system (wheat).
A field experiment was undertaken near Bonn, Germany on a Haplic Luvisol developed from loess. Lucerne (Medicago sativa L.) and chicory (Cichorium intybus L.) were grown as precrops in a field trial followed by spring wheat (Triticum aestivum L.) and mallow (Malva sylvestris L.). Biopore density was measured on horizontal areas of 50 x 50 cm. RLD was estimated using the profile wall method to 160 cm soil depth. Roots growing in biopores with a diameter > 2 mm were recorded separately from the roots in the bulk soil.
Biopore density was higher after chicory compared to lucerne cultivation. RLD of wheat in the topsoil was higher and in the subsoil lower than RLD of mallow. RLD in biopores of mallow was higher than of wheat. Both crops showed higher RLD in biopores after chicory.
The results indicate that the response of root growth to the presence of biopores is more pronounced for tap root systems than for fibrous root systems.