Root morphological changes in maize and soybean intercropping system under different phosphorus levels

Abstract

A pot experiment was conducted to investigate the changes of root morphology and its relationship with P uptake under different P levels (0, 50 and 100 mg P2O5·kg-1, represented by P0, P50 and P100, respectively). The results showed that intercropping significantly changed root morphological parameters of both maize and soybean, and increased the root:shoot ratio in soybean under different P levels. Intercropping significantly increased root length, root surface area, root volume, and root dry weight of maize and soybean by 25.6%, 22.0%, 39.2%, 34.3% and 28.1%, 29.7%, 37.3%, 62.3%, respectively, but significantly decreased the average root diameter by 15.2% and 11.7% compared to corresponding monoculture. The phosphorus uptake equivalent ratio (LERP) was >1, showing P uptake advantage of intercropping and that the LERP were unaffected by P levels. The root morphological changes induced by intercropping were closely related to P uptake improvement. The increases of maize root surface area and soybean root length were the main mechanisms driving efficient P uptake in maize and soybean intercropping. Based on the regression equation, 10% increase of maize root surface area or soybean root length caused 5%-10% increase of phosphorus uptake. P uptake of intercropped maize was not declined under P50 level compared to that of monoculture supplied with P100 level. In conclusion, maize and soybean intercropping has the potential to maintain crop P uptake when reducing application of phosphate fertilizer.