Effects of photosynthetic properties, soil environment and bioactive constituents of Eucommia ulmoides Oliver under two planting models.

Background: The distinct cultivation approaches of Eucommia ulmoides Oliver (EUO) have significant impacts on the planting environment, yield, content of bioactive constituents, and economic benefits. In this study, we systematically investigated the effects of the traditional arbor forest model of EUO planting (AFMEP) and the using leaf model of EUO planting (ULMEP), a dwarf dense planting model, on various parameters. These parameters include physicochemical properties, microbial diversity, and enzyme activities of the soil, as well as photosynthetic characteristics, active ingredient content, and carbon storage of the plant, alongside the economic benefits of EUO.

Results: The maximum net photosynthetic rate of ULMEP leaves increased by 128.4% compared to that of AFMEP leaves. The contents of alkali-hydrolyzable nitrogen, available phosphorus, organic matter, and total soluble salts in the ULMEP soil were 0.91-1.68 mg kg⁻¹, 0.25-1.0 mg kg⁻¹, 1.03-4.27 g kg⁻¹, and 0.06-0.11 g kg⁻¹ lower than those in the AFMEP soil, respectively. Soil moisture content in different layers of the ULMEP was higher than that of the AFMEP. Except for urease activity, no significant differences were found in the enzymatic activities of the rhizosphere soil between the two models. Acidobacteria and Zygomycota, which prefer low-nutrient environments, show higher relative abundance in the ULMEP soil. In contrast, Ascomycota and Basidiomycota, which favor nutrient-rich environments, were more relatively abundant in the AFMEP soil. The relative abundance of oligotrophic bacteria in ULMEP was higher than that in AFMEP, while the eutrophic bacteria were more abundant in AFMEP as compared to ULMEP. Meanwhile, the geniposidic acid, chlorogenic acid, and aucubin content in ULMEP leaves increased by 94.2%, 39.0%, and 75.8%, respectively. The carbon storage and economic efficiency in plants under ULMEP were three times more than those in AFMEP.

Conclusions: ULMEP has excellent economic and ecological benefits, making it a suitable planting model for producing bark and leaves. This may result from the combined effects of genotypes, environmental factors, management practices, and their interactions. These results provide important information for the selection and management of future EUO cultivation models.