Additions of Liriodendron sino-americanum Leaf Powder Change Soil Quality, Improve Sarcandra glabra Growth, and Alter Microbial Community

The interspecific relationship of plants plays a significant role in the agroforestry ecosystem. Chemical compounds release from litter exudates and decomposition was an important form of plant interspecific interaction and induced a series of biological reaction in adjacent plants. The objectives of the present study are to examine the effects of Liriodendron sino-americanum leaf powder on soil quality, plant growth and second metabolites accumulation, and rhizosphere microbial community, taking Sarcandra glabra (Thunb.) Nakai saplings as the host plant. A pot experiment was carried out under greenhouse conditions. The experiment comprised three treatments (CK (no addition), C75 (7.5% dosage addition), and C100 (10% dosage addition)) laid down in a completely randomized design with three replicates. Plant growth, second metabolites, and chlorophyll content were evaluated. Soil properties were also studied after plants were harvested, and the rhizosphere microbial community was determined via high-throughput sequencing. The addition of L. sino-americanum leaf powder increased the soil quality significantly, including the index of pH, soil organic carbon, and available nutrients of nitrogen, phosphorus, and potassium. With the dosage increase of L. sino-americanum leaf powder, dry weight of plant shoot and root, chlorophyll b concentration, and plant height increased continuously; however, chlorophyll a and rosmarinic acid increased firstly and then decreased. Moreover, the structure and composition of the rhizosphere microbial community were affected by L. sino-americanum leaf powder, and the effects on microbial diversity presented as a hormesis effect in dose. Statistical analyses further revealed that rhizospheric microbial community composition in relative abundance was highly related to the organic matter promoted by the addition of L. sino-americanum leaf powder. L. sino-americanum leaf plays positive effects on the cultivation of Sarcandra glabra under the forest, through litter exudates and decomposition, suggesting that cultivativation of Sarcandra glabra under L. sino-americanum plantation will achieve great economic, ecological, and social benefits.