Wheat and Faba Bean Intercropping Stimulates Non-Phenolic Organic Acids Exuded By Roots but Mitigates Phenolic Acids Exudation.

Organic acid is one of the most important constituents in root exudates, which plays important roles in rhizospheric plant-microbe interactions. The characteristic of non-phenolic and phenolic organic acids exuded by roots in legume and cereal intercropping is still scarce though much attention has given to intercropping. Hydroponic and soil culture experiments with three planting pattern treatments, wheat monocropped, faba bean monocropped, and wheat intercropped with faba bean were carried out. Root exudations at different growth stages were collected, and main components of organic acids in root exudation were detected by HPLC. Exudation rate of organic acids was calculated too. The results showed that oxalic, lactic, acetic, citric, fumairc, ρ-hydroxybenzoic, vanillic, and syringic acids were the main components of organic acid in root exudates of wheat and faba bean. However, the exudation rate of each organic acid and the components of major organic acids in root exudations were dynamic and varied with planting patterns. The total exudation rate of non-phenolic organic acids for wheat was increased by 35.6%-155% when wheat was intercropped with faba bean, relative to monocropped wheat, and non-phenolic organic acids exuded by intercropping faba bean was increased by 38.7%-97.4% when compared to monocropped faba bean. By contrast, the total exudation rate of phenolic acids in root exudations was decreased by 30%-60% under the wheat and faba bean intercropping system compared with that from monocropped faba bean. Additionally, different components of organic acids in root exudation were found between intercropping and monocropping. In conclusion, wheat and faba bean intercropping changed the root exudation pattern, maybe deducing different rhizodepositions. It provides information for why plant-plant interaction regulates root–soil interaction driving different rhizosphere processes in intercropping.