Soybean triggers morphological responses of tomato roots by modifying P capture under low P condition

Abstract

Abstract Background and aims Plant roots alter morphology to respond nutrients and neighbors, but whether neighbors influence the root architecture by modifying the availability of N and P nutrients is still unclear. Here we aimed to screen intercropping plants that cause changes in tomato root architecture and explore the role of nutrients. Methods We carried out the experiments of tomato-neighbor interactions to survey root morphological responses of target tomato seedlings. Then we investigated root plastic response to intercropping soybean under different P (0, 100, 200 mg P205 kg− 1 soil) or N (0, 100, 200 mg N kg− 1 soil) levels. In addition, we investigated the effects and physiological mechanisms of intercropping soybean on P capture of tomato seedlings. Results The intercropping soybean changed the horizontal symmetry of tomato roots, the dry weight and total root length of tomato roots in the ‘Toword’ region were significantly higher than those in the ‘Away’ region, while other intercropping plants did not. P rather than N levels, significantly affected the phenotypic plasticity of tomato roots in soybean intercropping systems. Under phosphorus deficiency condition, tomato roots showed a tendency to soybean. This phenomenon disappeared when the P supply increased in the soil. Under low P condition, intercropped soybean significantly increased the P concentration of tomato plants and the available P content of rhizosphere soil. Compared with tomatoes, soybean roots secreted more acid phosphatase, protons and organic acids. Conclusions Soybean triggers morphological responses of tomato roots through modifying P capture mediated by root exudates under low P condition.