Maize intercropping enriches plant growth-promoting rhizobacteria and promotes both the growth and volatile oil concentration of Atractylodes lancea

Abstract

In the <i>Atractylodes lancea</i> (<i>A. lancea</i>)-maize intercropping system, maize can promote the growth of <i>A. lancea</i>, but it is unclear whether this constitutes an aboveground or belowground process. In this study, we investigated the mechanisms of the root system interaction between <i>A. lancea</i> and maize using three different barrier conditions: no barrier (AI), nylon barrier (AN), and plastic barrier (AP) systems. The biomass, volatile oil concentration, physicochemical properties of the soil, and rhizosphere microorganisms of the <i>A. lancea</i> plant were determined. The results showed that (1) the <i>A. lancea</i> - maize intercropping system could promote the growth of <i>A. lancea</i> and its accumulation of volatile oils; (2) a comparison of the CK, AI, and AP treatments revealed that it was the above-ground effect of maize specifically that promoted the accumulation of both atractylon and atractylodin within the volatile oils of <i>A. lancea</i>, but inhibited the accumulation of hinesol and β-eudesmol; (3) in comparing the soil physicochemical properties of each treatment group, intercropping maize acidified the root soil of <i>A. lancea</i>, changed its root soil physicochemical properties, and increased the abundance of the acidic rhizosphere microbes of <i>A. lancea</i> at the phylum level; (4) in an analysis of rhizosphere microbial communities of <i>A. lancea</i> under different barrier systems, intercropping was found to promote plant growth-promoting rhizobacteria (PGPR) enrichment, including <i>Streptomyces</i>, <i>Bradyrhizobium</i>, <i>Candidatus Solibacter</i>, <i>Gemmatirosa</i>, and <i>Pseudolabrys</i>, and the biomass of <i>A. lancea</i> was significantly influenced by PGPR. In summary, we found that the rhizosphere soil of <i>A. lancea</i> was acidified in intercropping with maize, causing the accumulation of PGPR, which was beneficial to the growth of <i>A. lancea</i>.