Intercropping with Solanum sect. Solanum (Solanaceae) increases selenium uptake of ‘Summer Black’ grapevine

To improve the selenium (Se) absorption of grape, in this study, a pot experiment was carried out to study the effects of intercropping with four Solanum sect. Solanum (Solanaceae), including Solanum nigrum var. humile, Solanum diphyllum, Solanum nigrum, and Solanum alatum, on the Se absorption of ‘Summer Black’ grapevine. Intercropping increased the malondialdehyde contents in ‘Summer Black’ grapevine, which in turn reduced the biomass, photosynthetic pigments (chlorophyll a, chlorophyll b, carotenoid) contents, and antioxidant enzymes (superoxide dismutase, peroxidase, and catalase) activities of ‘Summer Black’ grapevine. Except S. alatum, intercropping with S. nigrum var. humile, S. diphyllum, and S. nigrum increased the Se content in ‘Summer Black’ grapevine, which increased the shoot Se content of ‘Summer Black’ grapevine by 56.2%, 18.1%, and 45.1%, respectively, compared with the monoculture. Additionally, correlation and grey relational analyses revealed that the root Se content was the most closely associated with the shoot Se content. In conclusion, intercropping with S. nigrum var. humile, S. diphyllum, and S. nigrum promote the Se accumulation in ‘Summer Black’ grapevine but inhibit its growth, and intercropping with S. nigrum var. humile has the best effect on the improvement of Se level in ‘Summer Black’ grapevine, which can be used for Se-enriched grape production.